Merge remote-tracking branch 'origin/main' into alternative-instruction-operand-flow

cpp/ql/src/Metrics/Files/FNumberOfTests.ql

@@ -18,6 +18,9 @@ Expr getTest() {
   or
   // boost tests; http://www.boost.org/
   result.(FunctionCall).getTarget().hasQualifiedName("boost::unit_test", "make_test_case")
+  or
+  // googletest tests; https://github.com/google/googletest/
+  result.(FunctionCall).getTarget().hasQualifiedName("testing::internal", "MakeAndRegisterTestInfo")
 }
 
 from File f, int n

cpp/ql/src/Microsoft/SAL.qll

@@ -1,5 +1,13 @@
+/**
+ * Provides classes for identifying and reasoning about Microsoft source code
+ * annotation language (SAL) macros.
+ */
+
 import cpp
 
+/**
+ * A SAL macro defined in `sal.h` or a similar header file.
+ */
 class SALMacro extends Macro {
   SALMacro() {
     exists(string filename | filename = this.getFile().getBaseName() |
@@ -20,27 +28,34 @@ class SALMacro extends Macro {
 }
 
 pragma[noinline]
-predicate isTopLevelMacroAccess(MacroAccess ma) { not exists(ma.getParentInvocation()) }
+private predicate isTopLevelMacroAccess(MacroAccess ma) { not exists(ma.getParentInvocation()) }
 
+/**
+ * An invocation of a SAL macro (excluding invocations inside other macros).
+ */
 class SALAnnotation extends MacroInvocation {
   SALAnnotation() {
     this.getMacro() instanceof SALMacro and
     isTopLevelMacroAccess(this)
   }
 
-  /** Returns the `Declaration` annotated by `this`. */
+  /** Gets the `Declaration` annotated by `this`. */
   Declaration getDeclaration() {
     annotatesAt(this, result.getADeclarationEntry(), _, _) and
     not result instanceof Type // exclude typedefs
   }
 
-  /** Returns the `DeclarationEntry` annotated by `this`. */
+  /** Gets the `DeclarationEntry` annotated by `this`. */
   DeclarationEntry getDeclarationEntry() {
     annotatesAt(this, result, _, _) and
     not result instanceof TypeDeclarationEntry // exclude typedefs
   }
 }
 
+/**
+ * A SAL macro indicating that the return value of a function should always be
+ * checked.
+ */
 class SALCheckReturn extends SALAnnotation {
   SALCheckReturn() {
     exists(SALMacro m | m = this.getMacro() |
@@ -50,6 +65,10 @@ class SALCheckReturn extends SALAnnotation {
   }
 }
 
+/**
+ * A SAL macro indicating that a pointer variable or return value should not be
+ * `NULL`.
+ */
 class SALNotNull extends SALAnnotation {
   SALNotNull() {
     exists(SALMacro m | m = this.getMacro() |
@@ -69,6 +88,9 @@ class SALNotNull extends SALAnnotation {
   }
 }
 
+/**
+ * A SAL macro indicating that a value may be `NULL`.
+ */
 class SALMaybeNull extends SALAnnotation {
   SALMaybeNull() {
     exists(SALMacro m | m = this.getMacro() |
@@ -79,13 +101,29 @@ class SALMaybeNull extends SALAnnotation {
   }
 }
 
+/**
+ * A parameter annotated by one or more SAL annotations.
+ */
+class SALParameter extends Parameter {
+  /** One of this parameter's annotations. */
+  SALAnnotation a;
+
+  SALParameter() { annotatesAt(a, this.getADeclarationEntry(), _, _) }
+
+  predicate isIn() { a.getMacroName().toLowerCase().matches("%\\_in%") }
+
+  predicate isOut() { a.getMacroName().toLowerCase().matches("%\\_out%") }
+
+  predicate isInOut() { a.getMacroName().toLowerCase().matches("%\\_inout%") }
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Implementation details
 /**
  * Holds if `a` annotates the declaration entry `d` and
  * its start position is the `idx`th position in `file` that holds a SAL element.
  */
-predicate annotatesAt(SALAnnotation a, DeclarationEntry d, File file, int idx) {
+private predicate annotatesAt(SALAnnotation a, DeclarationEntry d, File file, int idx) {
   annotatesAtPosition(a.(SALElement).getStartPosition(), d, file, idx)
 }
 
@@ -109,22 +147,6 @@ private predicate annotatesAtPosition(SALPosition pos, DeclarationEntry d, File
   )
 }
 
-/**
- * A parameter annotated by one or more SAL annotations.
- */
-class SALParameter extends Parameter {
-  /** One of this parameter's annotations. */
-  SALAnnotation a;
-
-  SALParameter() { annotatesAt(a, this.getADeclarationEntry(), _, _) }
-
-  predicate isIn() { a.getMacroName().toLowerCase().matches("%\\_in%") }
-
-  predicate isOut() { a.getMacroName().toLowerCase().matches("%\\_out%") }
-
-  predicate isInOut() { a.getMacroName().toLowerCase().matches("%\\_inout%") }
-}
-
 /**
  * A SAL element, that is, a SAL annotation or a declaration entry
  * that may have SAL annotations.

cpp/ql/src/Security/CWE/CWE-190/TaintedAllocationSize.ql

@@ -4,7 +4,7 @@
  *              user can result in integer overflow.
  * @kind path-problem
  * @problem.severity error
- * @precision high
+ * @precision medium
  * @id cpp/uncontrolled-allocation-size
  * @tags reliability
  *       security

cpp/ql/src/experimental/Security/CWE/CWE-120/MemoryUnsafeFunctionScan.cpp

@@ -0,0 +1,25 @@
+///// Library routines /////
+
+int scanf(const char *format, ...);
+int sscanf(const char *str, const char *format, ...);
+int fscanf(const char *str, const char *format, ...);
+
+///// EXAMPLES /////
+
+int main(int argc, char **argv)
+{
+
+    // BAD, do not use scanf without specifying a length first
+    char buf1[10];
+    scanf("%s", buf1);
+
+    // GOOD, length is specified. The length should be one less than the size of the buffer, since the last character is the NULL terminator.
+    char buf2[10];
+    sscanf(buf2, "%9s");
+
+    // BAD, do not use scanf without specifying a length first
+    char file[10];
+    fscanf(file, "%s", buf2);
+
+    return 0;
+}

cpp/ql/src/experimental/Security/CWE/CWE-120/MemoryUnsafeFunctionScan.qhelp

@@ -0,0 +1,25 @@
+<!DOCTYPE qhelp PUBLIC
+  "-//Semmle//qhelp//EN"
+  "qhelp.dtd">
+<qhelp>
+<overview>
+<p>It is bad practice to use any of the <code>scanf</code> functions without including a specified length within the format parameter, as it will be vulnerable to buffer overflows.</p>
+
+</overview>
+
+<recommendation>
+
+<p>Specify a length within the format string parameter, and make this length one less than the size of the buffer, since the last character should be reserved for the NULL terminator.</p>
+
+</recommendation>
+
+<example>
+<p>The following example demonstrates safe and unsafe uses of <code>scanf</code> type functions.</p>
+<sample src="MemoryUnsafeFunctionScan.cpp" />
+
+</example>
+
+<references>
+</references>
+
+</qhelp>

cpp/ql/src/experimental/Security/CWE/CWE-120/MemoryUnsafeFunctionScan.ql

@@ -0,0 +1,19 @@
+/**
+ * @name Scanf function without a specified length
+ * @description Use of one of the scanf functions without a specified length.
+ * @kind problem
+ * @problem.severity warning
+ * @id cpp/memory-unsafe-function-scan
+ * @tags reliability
+ *       security
+ *       external/cwe/cwe-120
+ */
+
+import cpp
+import semmle.code.cpp.commons.Scanf
+
+from FunctionCall call, ScanfFunction sff
+where
+  call.getTarget() = sff and
+  call.getArgument(sff.getFormatParameterIndex()).getValue().regexpMatch(".*%l?s.*")
+select call, "Dangerous use of one of the scanf functions"

cpp/ql/src/experimental/Security/CWE/CWE-359/PrivateCleartextWrite.qhelp

@@ -0,0 +1,32 @@
+<!DOCTYPE qhelp PUBLIC
+  "-//Semmle//qhelp//EN"
+  "qhelp.dtd">
+<qhelp>
+<overview>
+<p>Private data that is stored in a file or buffer unencrypted is accessible to an attacker who gains access to the
+storage.</p>
+
+</overview>
+<recommendation>
+
+<p>Ensure that private data is always encrypted before being stored.
+It may be wise to encrypt information before it is put into a buffer that may be readable in memory.</p>
+
+<p>In general, decrypt private data only at the point where it is necessary for it to be used in
+cleartext.</p>
+
+</recommendation>
+
+<references>
+
+<li><a href="https://owasp.org/www-project-top-ten/OWASP_Top_Ten_2017/Top_10-2017_A3-Sensitive_Data_Exposure">OWASP Sensitive_Data_Exposure</a></li>
+<li>M. Dowd, J. McDonald and J. Schuhm, <i>The Art of Software Security Assessment</i>, 1st Edition, Chapter 2 - 'Common Vulnerabilities of Encryption', p. 43. Addison Wesley, 2006.</li> 
+<li>M. Howard and D. LeBlanc, <i>Writing Secure Code</i>, 2nd Edition, Chapter 9 - 'Protecting Secret Data', p. 299. Microsoft, 2002.</li>
+
+
+
+<!--  LocalWords:  CWE
+ -->
+
+</references>
+</qhelp>

cpp/ql/src/experimental/Security/CWE/CWE-359/PrivateCleartextWrite.ql

@@ -0,0 +1,21 @@
+/**
+ * @name Exposure of private information
+ * @description If private information is written to an external location, it may be accessible by
+ *              unauthorized persons.
+ * @kind path-problem
+ * @problem.severity error
+ * @id cpp/private-cleartext-write
+ * @tags security
+ *       external/cwe/cwe-359
+ */
+
+import cpp
+import experimental.semmle.code.cpp.security.PrivateCleartextWrite
+import experimental.semmle.code.cpp.security.PrivateCleartextWrite::PrivateCleartextWrite
+import DataFlow::PathGraph
+
+from WriteConfig b, DataFlow::PathNode source, DataFlow::PathNode sink
+where b.hasFlowPath(source, sink)
+select sink.getNode(),
+  "This write into the external location '" + sink + "' may contain unencrypted data from $@",
+  source, "this source."

cpp/ql/src/experimental/semmle/code/cpp/models/interfaces/SimpleRangeAnalysisExpr.qll

@@ -0,0 +1,78 @@
+/**
+ * EXPERIMENTAL: The API of this module may change without notice.
+ *
+ * Provides a class for modeling `Expr`s with a restricted range.
+ */
+
+import cpp
+import semmle.code.cpp.rangeanalysis.SimpleRangeAnalysis
+
+/**
+ * EXPERIMENTAL: The API of this class may change without notice.
+ *
+ * An expression for which a range can be deduced. Extend this class to add
+ * functionality to the range analysis library.
+ */
+abstract class SimpleRangeAnalysisExpr extends Expr {
+  /**
+   * Gets the lower bound of the expression.
+   *
+   * Implementations of this predicate should use
+   * `getFullyConvertedLowerBounds` and `getFullyConvertedUpperBounds` for
+   * recursive calls to get the bounds of their children.
+   */
+  abstract float getLowerBounds();
+
+  /**
+   * Gets the upper bound of the expression.
+   *
+   * Implementations of this predicate should use
+   * `getFullyConvertedLowerBounds` and `getFullyConvertedUpperBounds` for
+   * recursive calls to get the bounds of their children.
+   */
+  abstract float getUpperBounds();
+
+  /**
+   * Holds if the range this expression depends on the definition `srcDef` for
+   * StackVariable `srcVar`.
+   *
+   * Because this predicate cannot be recursive, most implementations should
+   * override `dependsOnChild` instead.
+   */
+  predicate dependsOnDef(RangeSsaDefinition srcDef, StackVariable srcVar) { none() }
+
+  /**
+   * Holds if this expression depends on the range of its unconverted
+   * subexpression `child`. This information is used to inform the range
+   * analysis about cyclic dependencies. Without this information, range
+   * analysis might work for simple cases but will go into infinite loops on
+   * complex code.
+   *
+   * For example, when modeling a function call whose return value depends on
+   * all of its arguments, implement this predicate as
+   * `child = this.getAnArgument()`.
+   */
+  abstract predicate dependsOnChild(Expr child);
+}
+
+import SimpleRangeAnalysisInternal
+
+/**
+ * This class exists to prevent the QL front end from emitting compile errors
+ * inside `SimpleRangeAnalysis.qll` about certain conjuncts being empty
+ * because the overrides of `SimpleRangeAnalysisExpr` that happen to be in
+ * scope do not make use of every feature it offers.
+ */
+private class Empty extends SimpleRangeAnalysisExpr {
+  Empty() {
+    // This predicate is complicated enough that the QL type checker doesn't
+    // see it as empty but simple enough that the optimizer should.
+    this = this and none()
+  }
+
+  override float getLowerBounds() { none() }
+
+  override float getUpperBounds() { none() }
+
+  override predicate dependsOnChild(Expr child) { none() }
+}

cpp/ql/src/experimental/semmle/code/cpp/security/PrivateCleartextWrite.qll

@@ -0,0 +1,63 @@
+/**
+ * Provides a taint-tracking configuration for reasoning about private information flowing unencrypted to an external location.
+ */
+
+import cpp
+import semmle.code.cpp.dataflow.TaintTracking
+import experimental.semmle.code.cpp.security.PrivateData
+import semmle.code.cpp.security.FileWrite
+import semmle.code.cpp.security.BufferWrite
+import semmle.code.cpp.dataflow.TaintTracking
+
+module PrivateCleartextWrite {
+  /**
+   * A data flow source for private information flowing unencrypted to an external location.
+   */
+  abstract class Source extends DataFlow::ExprNode { }
+
+  /**
+   * A data flow sink for private information flowing unencrypted to an external location.
+   */
+  abstract class Sink extends DataFlow::ExprNode { }
+
+  /**
+   * A sanitizer for private information flowing unencrypted to an external location.
+   */
+  abstract class Sanitizer extends DataFlow::ExprNode { }
+
+  /** A call to any method whose name suggests that it encodes or encrypts the parameter. */
+  class ProtectSanitizer extends Sanitizer {
+    ProtectSanitizer() {
+      exists(Function m, string s |
+        this.getExpr().(FunctionCall).getTarget() = m and
+        m.getName().regexpMatch("(?i).*" + s + ".*")
+      |
+        s = "protect" or s = "encode" or s = "encrypt"
+      )
+    }
+  }
+
+  class WriteConfig extends TaintTracking::Configuration {
+    WriteConfig() { this = "Write configuration" }
+
+    override predicate isSource(DataFlow::Node source) { source instanceof Source }
+
+    override predicate isSink(DataFlow::Node sink) { sink instanceof Sink }
+
+    override predicate isSanitizer(DataFlow::Node node) { node instanceof Sanitizer }
+  }
+
+  class PrivateDataSource extends Source {
+    PrivateDataSource() { this.getExpr() instanceof PrivateDataExpr }
+  }
+
+  class WriteSink extends Sink {
+    WriteSink() {
+      exists(FileWrite f, BufferWrite b |
+        this.asExpr() = f.getASource()
+        or
+        this.asExpr() = b.getAChild()
+      )
+    }
+  }
+}

cpp/ql/src/experimental/semmle/code/cpp/security/PrivateData.qll

@@ -0,0 +1,53 @@
+/**
+ * Provides classes and predicates for identifying private data and functions for security.
+ *
+ * 'Private' data in general is anything that would compromise user privacy if exposed. This
+ * library tries to guess where private data may either be stored in a variable or produced by a
+ * function.
+ *
+ * This library is not concerned with credentials. See `SensitiveActions` for expressions related
+ * to credentials.
+ */
+
+import cpp
+
+/** A string for `match` that identifies strings that look like they represent private data. */
+private string privateNames() {
+  // Inspired by the list on https://cwe.mitre.org/data/definitions/359.html
+  // Government identifiers, such as Social Security Numbers
+  result = "%social%security%number%" or
+  // Contact information, such as home addresses and telephone numbers
+  result = "%postcode%" or
+  result = "%zipcode%" or
+  // result = "%telephone%" or
+  // Geographic location - where the user is (or was)
+  result = "%latitude%" or
+  result = "%longitude%" or
+  // Financial data - such as credit card numbers, salary, bank accounts, and debts
+  result = "%creditcard%" or
+  result = "%salary%" or
+  result = "%bankaccount%" or
+  // Communications - e-mail addresses, private e-mail messages, SMS text messages, chat logs, etc.
+  // result = "%email%" or
+  // result = "%mobile%" or
+  result = "%employer%" or
+  // Health - medical conditions, insurance status, prescription records
+  result = "%medical%"
+}
+
+/** An expression that might contain private data. */
+abstract class PrivateDataExpr extends Expr { }
+
+/** A functiond call that might produce private data. */
+class PrivateFunctionCall extends PrivateDataExpr, FunctionCall {
+  PrivateFunctionCall() {
+    exists(string s | this.getTarget().getName().toLowerCase() = s | s.matches(privateNames()))
+  }
+}
+
+/** An access to a variable that might contain private data. */
+class PrivateVariableAccess extends PrivateDataExpr, VariableAccess {
+  PrivateVariableAccess() {
+    exists(string s | this.getTarget().getName().toLowerCase() = s | s.matches(privateNames()))
+  }
+}

cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl.qll

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl2.qll

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl3.qll

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl4.qll

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImplCommon.qll

@@ -512,13 +512,19 @@ abstract class CallContext extends TCallContext {
   abstract predicate relevantFor(DataFlowCallable callable);
 }
 
-class CallContextAny extends CallContext, TAnyCallContext {
+abstract class CallContextNoCall extends CallContext { }
+
+class CallContextAny extends CallContextNoCall, TAnyCallContext {
   override string toString() { result = "CcAny" }
 
   override predicate relevantFor(DataFlowCallable callable) { any() }
 }
 
-abstract class CallContextCall extends CallContext { }
+abstract class CallContextCall extends CallContext {
+  /** Holds if this call context may be `call`. */
+  bindingset[call]
+  abstract predicate matchesCall(DataFlowCall call);
+}
 
 class CallContextSpecificCall extends CallContextCall, TSpecificCall {
   override string toString() {
@@ -529,6 +535,8 @@ class CallContextSpecificCall extends CallContextCall, TSpecificCall {
     recordDataFlowCallSite(getCall(), callable)
   }
 
+  override predicate matchesCall(DataFlowCall call) { call = this.getCall() }
+
   DataFlowCall getCall() { this = TSpecificCall(result) }
 }
 
@@ -538,9 +546,11 @@ class CallContextSomeCall extends CallContextCall, TSomeCall {
   override predicate relevantFor(DataFlowCallable callable) {
     exists(ParameterNode p | p.getEnclosingCallable() = callable)
   }
+
+  override predicate matchesCall(DataFlowCall call) { any() }
 }
 
-class CallContextReturn extends CallContext, TReturn {
+class CallContextReturn extends CallContextNoCall, TReturn {
   override string toString() {
     exists(DataFlowCall call | this = TReturn(_, call) | result = "CcReturn(" + call + ")")
   }

cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImplLocal.qll

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

cpp/ql/src/semmle/code/cpp/exprs/Expr.qll

@@ -539,6 +539,17 @@ class BinaryOperation extends Operation, @bin_op_expr {
   /** Gets the right operand of this binary operation. */
   Expr getRightOperand() { this.hasChild(result, 1) }
 
+  /**
+   * Holds if `e1` and `e2` (in either order) are the two operands of this
+   * binary operation.
+   */
+  predicate hasOperands(Expr e1, Expr e2) {
+    exists(int i | i in [0, 1] |
+      this.hasChild(e1, i) and
+      this.hasChild(e2, 1 - i)
+    )
+  }
+
   override string toString() { result = "... " + this.getOperator() + " ..." }
 
   override predicate mayBeImpure() {

cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl.qll

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl2.qll

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl3.qll

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl4.qll

@@ -1066,7 +1066,7 @@ private module LocalFlowBigStep {
    * Holds if `node` can be the first node in a maximal subsequence of local
    * flow steps in a dataflow path.
    */
-  private predicate localFlowEntry(Node node, Configuration config) {
+  predicate localFlowEntry(Node node, Configuration config) {
     nodeCand2(node, config) and
     (
       config.isSource(node) or
@@ -1650,53 +1650,53 @@ private class AccessPathOption extends TAccessPathOption {
  * Holds if `node` is reachable with access path `ap` from a source in
  * the configuration `config`.
  *
- * The Boolean `fromArg` records whether the node is reached through an
+ * The call context `cc` records whether the node is reached through an
  * argument in a call, and if so, `argAp` records the access path of that
  * argument.
  */
 private predicate flowFwd(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwd0(node, fromArg, argAp, apf, ap, config) and
+  flowFwd0(node, cc, argAp, apf, ap, config) and
   flowCand(node, _, _, apf, config)
 }
 
 private predicate flowFwd0(
-  Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
   flowCand(node, _, _, _, config) and
   config.isSource(node) and
-  fromArg = false and
+  cc instanceof CallContextAny and
   argAp = TAccessPathNone() and
   ap = TNil(getNodeType(node)) and
   apf = ap.(AccessPathNil).getFront()
   or
   flowCand(node, _, _, _, unbind(config)) and
   (
-    exists(Node mid |
-      flowFwd(mid, fromArg, argAp, apf, ap, config) and
-      localFlowBigStep(mid, node, true, _, config, _)
+    exists(Node mid, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, apf, ap, localCC, config) and
+      localFlowBigStep(mid, node, true, _, config, localCC)
     )
     or
-    exists(Node mid, AccessPathNil nil |
-      flowFwd(mid, fromArg, argAp, _, nil, config) and
-      localFlowBigStep(mid, node, false, apf, config, _) and
+    exists(Node mid, AccessPathNil nil, LocalCallContext localCC |
+      flowFwdLocalEntry(mid, cc, argAp, _, nil, localCC, config) and
+      localFlowBigStep(mid, node, false, apf, config, localCC) and
       apf = ap.(AccessPathNil).getFront()
     )
     or
     exists(Node mid |
       flowFwd(mid, _, _, apf, ap, config) and
       jumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone()
     )
     or
     exists(Node mid, AccessPathNil nil |
       flowFwd(mid, _, _, _, nil, config) and
       additionalJumpStep(mid, node, config) and
-      fromArg = false and
+      cc instanceof CallContextAny and
       argAp = TAccessPathNone() and
       ap = TNil(getNodeType(node)) and
       apf = ap.(AccessPathNil).getFront()
@@ -1704,40 +1704,51 @@ private predicate flowFwd0(
   )
   or
   // store
-  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, fromArg, argAp, config))
+  exists(TypedContent tc | flowFwdStore(node, tc, pop(tc, ap), apf, cc, argAp, config))
   or
   // read
   exists(TypedContent tc |
-    flowFwdRead(node, _, push(tc, ap), apf, fromArg, argAp, config) and
+    flowFwdRead(node, _, push(tc, ap), apf, cc, argAp, config) and
     flowFwdConsCand(tc, apf, ap, config)
   )
   or
   // flow into a callable
-  flowFwdIn(_, node, _, _, apf, ap, config) and
-  fromArg = true and
+  flowFwdIn(_, node, _, cc, _, apf, ap, config) and
   if flowCand(node, true, _, apf, config)
   then argAp = TAccessPathSome(ap)
   else argAp = TAccessPathNone()
   or
   // flow out of a callable
   exists(DataFlowCall call |
-    flowFwdOut(call, node, fromArg, argAp, apf, ap, config) and
-    fromArg = false
+    exists(DataFlowCallable c |
+      flowFwdOut(call, node, any(CallContextNoCall innercc), c, argAp, apf, ap, config) and
+      if reducedViableImplInReturn(c, call) then cc = TReturn(c, call) else cc = TAnyCallContext()
+    )
     or
     exists(AccessPath argAp0 |
       flowFwdOutFromArg(call, node, argAp0, apf, ap, config) and
-      flowFwdIsEntered(call, fromArg, argAp, argAp0, config)
+      flowFwdIsEntered(call, cc, argAp, argAp0, config)
     )
   )
 }
 
+pragma[nomagic]
+private predicate flowFwdLocalEntry(
+  Node node, CallContext cc, AccessPathOption argAp, AccessPathFront apf, AccessPath ap,
+  LocalCallContext localCC, Configuration config
+) {
+  flowFwd(node, cc, argAp, apf, ap, config) and
+  localFlowEntry(node, config) and
+  localCC = getLocalCallContext(cc, node.getEnclosingCallable())
+}
+
 pragma[nomagic]
 private predicate flowFwdStore(
-  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, TypedContent tc, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, AccessPathFront apf0 |
-    flowFwd(mid, fromArg, argAp, apf0, ap0, config) and
+    flowFwd(mid, cc, argAp, apf0, ap0, config) and
     flowFwdStore0(mid, tc, node, apf0, apf, config)
   )
 }
@@ -1764,20 +1775,20 @@ private predicate flowFwdStore0(
 
 pragma[nomagic]
 private predicate flowFwdRead0(
-  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2,
-  boolean fromArg, AccessPathOption argAp, Configuration config
+  Node node1, TypedContent tc, AccessPathFrontHead apf0, AccessPath ap0, Node node2, CallContext cc,
+  AccessPathOption argAp, Configuration config
 ) {
-  flowFwd(node1, fromArg, argAp, apf0, ap0, config) and
+  flowFwd(node1, cc, argAp, apf0, ap0, config) and
   readCandFwd(node1, tc, apf0, node2, config)
 }
 
 pragma[nomagic]
 private predicate flowFwdRead(
-  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, boolean fromArg,
+  Node node, AccessPathFrontHead apf0, AccessPath ap0, AccessPathFront apf, CallContext cc,
   AccessPathOption argAp, Configuration config
 ) {
   exists(Node mid, TypedContent tc |
-    flowFwdRead0(mid, tc, apf0, ap0, node, fromArg, argAp, config) and
+    flowFwdRead0(mid, tc, apf0, ap0, node, cc, argAp, config) and
     flowCand(node, _, _, apf, unbind(config)) and
     flowCandConsCand(tc, apf, unbind(config))
   )
@@ -1795,13 +1806,16 @@ private predicate flowFwdConsCand(
 
 pragma[nomagic]
 private predicate flowFwdIn(
-  DataFlowCall call, ParameterNode p, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, ParameterNode p, CallContext outercc, CallContext innercc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
-  exists(ArgumentNode arg, boolean allowsFieldFlow |
-    flowFwd(arg, fromArg, argAp, apf, ap, config) and
+  exists(ArgumentNode arg, boolean allowsFieldFlow, DataFlowCallable c |
+    flowFwd(arg, outercc, argAp, apf, ap, config) and
     flowIntoCallNodeCand2(call, arg, p, allowsFieldFlow, config) and
-    flowCand(p, _, _, _, unbind(config))
+    c = p.getEnclosingCallable() and
+    c = resolveCall(call, outercc) and
+    flowCand(p, _, _, _, unbind(config)) and
+    if recordDataFlowCallSite(call, c) then innercc = TSpecificCall(call) else innercc = TSomeCall()
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1809,13 +1823,19 @@ private predicate flowFwdIn(
 
 pragma[nomagic]
 private predicate flowFwdOut(
-  DataFlowCall call, Node node, boolean fromArg, AccessPathOption argAp, AccessPathFront apf,
-  AccessPath ap, Configuration config
+  DataFlowCall call, Node node, CallContext innercc, DataFlowCallable innerc,
+  AccessPathOption argAp, AccessPathFront apf, AccessPath ap, Configuration config
 ) {
   exists(ReturnNodeExt ret, boolean allowsFieldFlow |
-    flowFwd(ret, fromArg, argAp, apf, ap, config) and
+    flowFwd(ret, innercc, argAp, apf, ap, config) and
     flowOutOfCallNodeCand2(call, ret, node, allowsFieldFlow, config) and
-    flowCand(node, _, _, _, unbind(config))
+    innerc = ret.getEnclosingCallable() and
+    flowCand(node, _, _, _, unbind(config)) and
+    (
+      resolveReturn(innercc, innerc, call)
+      or
+      innercc.(CallContextCall).matchesCall(call)
+    )
   |
     ap instanceof AccessPathNil or allowsFieldFlow = true
   )
@@ -1826,7 +1846,7 @@ private predicate flowFwdOutFromArg(
   DataFlowCall call, Node node, AccessPath argAp, AccessPathFront apf, AccessPath ap,
   Configuration config
 ) {
-  flowFwdOut(call, node, true, TAccessPathSome(argAp), apf, ap, config)
+  flowFwdOut(call, node, any(CallContextCall ccc), _, TAccessPathSome(argAp), apf, ap, config)
 }
 
 /**
@@ -1834,10 +1854,10 @@ private predicate flowFwdOutFromArg(
  */
 pragma[nomagic]
 private predicate flowFwdIsEntered(
-  DataFlowCall call, boolean fromArg, AccessPathOption argAp, AccessPath ap, Configuration config
+  DataFlowCall call, CallContext cc, AccessPathOption argAp, AccessPath ap, Configuration config
 ) {
   exists(ParameterNode p, AccessPathFront apf |
-    flowFwdIn(call, p, fromArg, argAp, apf, ap, config) and
+    flowFwdIn(call, p, cc, _, argAp, apf, ap, config) and
     flowCand(p, true, TAccessPathFrontSome(_), apf, config)
   )
 }
@@ -1920,7 +1940,7 @@ private predicate flow0(
   // flow out of a callable
   flowOut(_, node, _, _, ap, config) and
   toReturn = true and
-  if flowFwd(node, true, TAccessPathSome(_), _, ap, config)
+  if flowFwd(node, any(CallContextCall ccc), TAccessPathSome(_), _, ap, config)
   then returnAp = TAccessPathSome(ap)
   else returnAp = TAccessPathNone()
 }
@@ -2006,9 +2026,10 @@ private predicate flowIsReturned(
   DataFlowCall call, boolean toReturn, AccessPathOption returnAp, AccessPath ap,
   Configuration config
 ) {
-  exists(ReturnNodeExt ret |
+  exists(ReturnNodeExt ret, CallContextCall ccc |
     flowOut(call, ret, toReturn, returnAp, ap, config) and
-    flowFwd(ret, true, TAccessPathSome(_), _, ap, config)
+    flowFwd(ret, ccc, TAccessPathSome(_), _, ap, config) and
+    ccc.matchesCall(call)
   )
 }
 
@@ -2031,7 +2052,7 @@ private newtype TSummaryCtx =
     exists(ReturnNodeExt ret, Configuration config, AccessPath ap0 |
       parameterFlow(p, ap, ret.getEnclosingCallable(), config) and
       flow(ret, true, TAccessPathSome(_), ap0, config) and
-      flowFwd(ret, true, TAccessPathSome(ap), _, ap0, config)
+      flowFwd(ret, any(CallContextCall ccc), TAccessPathSome(ap), _, ap0, config)
     )
   }
 
@@ -2352,7 +2373,7 @@ private predicate pathOutOfCallable0(
 ) {
   pos = getReturnPosition(mid.getNode()) and
   innercc = mid.getCallContext() and
-  not innercc instanceof CallContextCall and
+  innercc instanceof CallContextNoCall and
   ap = mid.getAp() and
   config = mid.getConfiguration()
 }
@@ -2867,7 +2888,7 @@ private module FlowExploration {
   ) {
     pos = getReturnPosition(mid.getNode()) and
     innercc = mid.getCallContext() and
-    not innercc instanceof CallContextCall and
+    innercc instanceof CallContextNoCall and
     ap = mid.getAp() and
     config = mid.getConfiguration()
   }

cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImplCommon.qll

@@ -512,13 +512,19 @@ abstract class CallContext extends TCallContext {
   abstract predicate relevantFor(DataFlowCallable callable);
 }
 
-class CallContextAny extends CallContext, TAnyCallContext {
+abstract class CallContextNoCall extends CallContext { }
+
+class CallContextAny extends CallContextNoCall, TAnyCallContext {
   override string toString() { result = "CcAny" }
 
   override predicate relevantFor(DataFlowCallable callable) { any() }
 }
 
-abstract class CallContextCall extends CallContext { }
+abstract class CallContextCall extends CallContext {
+  /** Holds if this call context may be `call`. */
+  bindingset[call]
+  abstract predicate matchesCall(DataFlowCall call);
+}
 
 class CallContextSpecificCall extends CallContextCall, TSpecificCall {
   override string toString() {
@@ -529,6 +535,8 @@ class CallContextSpecificCall extends CallContextCall, TSpecificCall {
     recordDataFlowCallSite(getCall(), callable)
   }
 
+  override predicate matchesCall(DataFlowCall call) { call = this.getCall() }
+
   DataFlowCall getCall() { this = TSpecificCall(result) }
 }
 
@@ -538,9 +546,11 @@ class CallContextSomeCall extends CallContextCall, TSomeCall {
   override predicate relevantFor(DataFlowCallable callable) {
     exists(ParameterNode p | p.getEnclosingCallable() = callable)
   }
+
+  override predicate matchesCall(DataFlowCall call) { any() }
 }
 
-class CallContextReturn extends CallContext, TReturn {
+class CallContextReturn extends CallContextNoCall, TReturn {
   override string toString() {
     exists(DataFlowCall call | this = TReturn(_, call) | result = "CcReturn(" + call + ")")
   }

cpp/ql/src/semmle/code/cpp/models/Models.qll

@@ -13,6 +13,7 @@ private import implementations.Strcat
 private import implementations.Strcpy
 private import implementations.Strdup
 private import implementations.Strftime
+private import implementations.StdContainer
 private import implementations.StdString
 private import implementations.Swap
 private import implementations.GetDelim

cpp/ql/src/semmle/code/cpp/models/implementations/StdContainer.qll

@@ -0,0 +1,102 @@
+/**
+ * Provides models for C++ containers `std::array`, `std::vector`, `std::deque`, `std::list` and `std::forward_list`.
+ */
+
+import semmle.code.cpp.models.interfaces.Taint
+
+/**
+ * Additional model for standard container constructors that reference the
+ * value type of the container (that is, the `T` in `std::vector<T>`).  For
+ * example the fill constructor:
+ * ```
+ * std::vector<std::string> v(100, potentially_tainted_string);
+ * ```
+ */
+class StdSequenceContainerConstructor extends Constructor, TaintFunction {
+  StdSequenceContainerConstructor() {
+    this.getDeclaringType().hasQualifiedName("std", "vector") or
+    this.getDeclaringType().hasQualifiedName("std", "deque") or
+    this.getDeclaringType().hasQualifiedName("std", "list") or
+    this.getDeclaringType().hasQualifiedName("std", "forward_list")
+  }
+
+  /**
+   * Gets the index of a parameter to this function that is a reference to the
+   * value type of the container.
+   */
+  int getAValueTypeParameterIndex() {
+    getParameter(result).getUnspecifiedType().(ReferenceType).getBaseType() =
+      getDeclaringType().getTemplateArgument(0) // i.e. the `T` of this `std::vector<T>`
+  }
+
+  override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+    // taint flow from any parameter of the value type to the returned object
+    input.isParameterDeref(getAValueTypeParameterIndex()) and
+    output.isReturnValue() // TODO: this should be `isQualifierObject` by our current definitions, but that flow is not yet supported.
+  }
+}
+
+/**
+ * The standard container functions `push_back` and `push_front`.
+ */
+class StdSequenceContainerPush extends TaintFunction {
+  StdSequenceContainerPush() {
+    this.hasQualifiedName("std", "vector", "push_back") or
+    this.hasQualifiedName("std", "deque", "push_back") or
+    this.hasQualifiedName("std", "deque", "push_front") or
+    this.hasQualifiedName("std", "list", "push_back") or
+    this.hasQualifiedName("std", "list", "push_front") or
+    this.hasQualifiedName("std", "forward_list", "push_front")
+  }
+
+  override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+    // flow from parameter to qualifier
+    input.isParameterDeref(0) and
+    output.isQualifierObject()
+  }
+}
+
+/**
+ * The standard container functions `front` and `back`.
+ */
+class StdSequenceContainerFrontBack extends TaintFunction {
+  StdSequenceContainerFrontBack() {
+    this.hasQualifiedName("std", "array", "front") or
+    this.hasQualifiedName("std", "array", "back") or
+    this.hasQualifiedName("std", "vector", "front") or
+    this.hasQualifiedName("std", "vector", "back") or
+    this.hasQualifiedName("std", "deque", "front") or
+    this.hasQualifiedName("std", "deque", "back") or
+    this.hasQualifiedName("std", "list", "front") or
+    this.hasQualifiedName("std", "list", "back") or
+    this.hasQualifiedName("std", "forward_list", "front")
+  }
+
+  override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+    // flow from object to returned reference
+    input.isQualifierObject() and
+    output.isReturnValueDeref()
+  }
+}
+
+/**
+ * The standard container `swap` functions.
+ */
+class StdSequenceContainerSwap extends TaintFunction {
+  StdSequenceContainerSwap() {
+    this.hasQualifiedName("std", "array", "swap") or
+    this.hasQualifiedName("std", "vector", "swap") or
+    this.hasQualifiedName("std", "deque", "swap") or
+    this.hasQualifiedName("std", "list", "swap") or
+    this.hasQualifiedName("std", "forward_list", "swap")
+  }
+
+  override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+    // container1.swap(container2)
+    input.isQualifierObject() and
+    output.isParameterDeref(0)
+    or
+    input.isParameterDeref(0) and
+    output.isQualifierObject()
+  }
+}

cpp/ql/src/semmle/code/cpp/models/implementations/StdString.qll

@@ -1,10 +1,20 @@
 import semmle.code.cpp.models.interfaces.Taint
 
 /**
- * The standard function `std::string.c_str`.
+ * The `std::basic_string` template class.
+ */
+class StdBasicString extends TemplateClass {
+  StdBasicString() { this.hasQualifiedName("std", "basic_string") }
+}
+
+/**
+ * The `std::string` functions `c_str` and  `data`.
  */
 class StdStringCStr extends TaintFunction {
-  StdStringCStr() { this.hasQualifiedName("std", "basic_string", "c_str") }
+  StdStringCStr() {
+    this.hasQualifiedName("std", "basic_string", "c_str") or
+    this.hasQualifiedName("std", "basic_string", "data")
+  }
 
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     // flow from string itself (qualifier) to return value
@@ -12,3 +22,126 @@ class StdStringCStr extends TaintFunction {
     output.isReturnValue()
   }
 }
+
+/**
+ * The `std::string` function `operator+`.
+ */
+class StdStringPlus extends TaintFunction {
+  StdStringPlus() {
+    this.hasQualifiedName("std", "operator+") and
+    this.getUnspecifiedType() = any(StdBasicString s).getAnInstantiation()
+  }
+
+  override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+    // flow from parameters to return value
+    (
+      input.isParameterDeref(0) or
+      input.isParameterDeref(1)
+    ) and
+    output.isReturnValue()
+  }
+}
+
+/**
+ * The `std::string` functions `operator+=`, `append`, `insert` and
+ * `replace`. All of these functions combine the existing string
+ * with a new string (or character) from one of the arguments.
+ */
+class StdStringAppend extends TaintFunction {
+  StdStringAppend() {
+    this.hasQualifiedName("std", "basic_string", "operator+=") or
+    this.hasQualifiedName("std", "basic_string", "append") or
+    this.hasQualifiedName("std", "basic_string", "insert") or
+    this.hasQualifiedName("std", "basic_string", "replace")
+  }
+
+  /**
+   * Gets the index of a parameter to this function that is a string (or
+   * character).
+   */
+  int getAStringParameter() {
+    getParameter(result).getType() instanceof PointerType or
+    getParameter(result).getType() instanceof ReferenceType or
+    getParameter(result).getType() = getDeclaringType().getTemplateArgument(0) // i.e. `std::basic_string::CharT`
+  }
+
+  override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+    // flow from string and parameter to string (qualifier) and return value
+    (
+      input.isQualifierObject() or
+      input.isParameterDeref(getAStringParameter())
+    ) and
+    (
+      output.isQualifierObject() or
+      output.isReturnValueDeref()
+    )
+  }
+}
+
+/**
+ * The standard function `std::string.assign`.
+ */
+class StdStringAssign extends TaintFunction {
+  StdStringAssign() { this.hasQualifiedName("std", "basic_string", "assign") }
+
+  /**
+   * Gets the index of a parameter to this function that is a string (or
+   * character).
+   */
+  int getAStringParameter() {
+    getParameter(result).getType() instanceof PointerType or
+    getParameter(result).getType() instanceof ReferenceType or
+    getParameter(result).getType() = getDeclaringType().getTemplateArgument(0) // i.e. `std::basic_string::CharT`
+  }
+
+  override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+    // flow from parameter to string itself (qualifier) and return value
+    input.isParameterDeref(getAStringParameter()) and
+    (
+      output.isQualifierObject() or
+      output.isReturnValueDeref()
+    )
+  }
+}
+
+/**
+ * The standard function `std::string.copy`.
+ */
+class StdStringCopy extends TaintFunction {
+  StdStringCopy() { this.hasQualifiedName("std", "basic_string", "copy") }
+
+  override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+    // copy(dest, num, pos)
+    input.isQualifierObject() and
+    output.isParameterDeref(0)
+  }
+}
+
+/**
+ * The standard function `std::string.substr`.
+ */
+class StdStringSubstr extends TaintFunction {
+  StdStringSubstr() { this.hasQualifiedName("std", "basic_string", "substr") }
+
+  override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+    // substr(pos, num)
+    input.isQualifierObject() and
+    output.isReturnValue()
+  }
+}
+
+/**
+ * The standard function `std::string.swap`.
+ */
+class StdStringSwap extends TaintFunction {
+  StdStringSwap() { this.hasQualifiedName("std", "basic_string", "swap") }
+
+  override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+    // str1.swap(str2)
+    input.isQualifierObject() and
+    output.isParameterDeref(0)
+    or
+    input.isParameterDeref(0) and
+    output.isQualifierObject()
+  }
+}

cpp/ql/src/semmle/code/cpp/rangeanalysis/SimpleRangeAnalysis.qll

@@ -44,6 +44,7 @@
 
 import cpp
 private import RangeAnalysisUtils
+private import experimental.semmle.code.cpp.models.interfaces.SimpleRangeAnalysisExpr
 import RangeSSA
 import SimpleRangeAnalysisCached
 private import NanAnalysis
@@ -126,7 +127,7 @@ private class UnsignedBitwiseAndExpr extends BitwiseAndExpr {
   UnsignedBitwiseAndExpr() {
     (
       getLeftOperand().getFullyConverted().getType().getUnderlyingType().(IntegralType).isUnsigned() or
-      getLeftOperand().getFullyConverted().getValue().toInt() >= 0
+      getValue(getLeftOperand().getFullyConverted()).toInt() >= 0
     ) and
     (
       getRightOperand()
@@ -135,7 +136,7 @@ private class UnsignedBitwiseAndExpr extends BitwiseAndExpr {
           .getUnderlyingType()
           .(IntegralType)
           .isUnsigned() or
-      getRightOperand().getFullyConverted().getValue().toInt() >= 0
+      getValue(getRightOperand().getFullyConverted()).toInt() >= 0
     )
   }
 }
@@ -156,6 +157,92 @@ float safeFloor(float v) {
   result = v
 }
 
+/** A `MulExpr` where exactly one operand is constant. */
+private class MulByConstantExpr extends MulExpr {
+  float constant;
+  Expr operand;
+
+  MulByConstantExpr() {
+    exists(Expr constantExpr |
+      this.hasOperands(constantExpr, operand) and
+      constant = getValue(constantExpr.getFullyConverted()).toFloat() and
+      not exists(getValue(operand.getFullyConverted()).toFloat())
+    )
+  }
+
+  /** Gets the value of the constant operand. */
+  float getConstant() { result = constant }
+
+  /** Gets the non-constant operand. */
+  Expr getOperand() { result = operand }
+}
+
+private class UnsignedMulExpr extends MulExpr {
+  UnsignedMulExpr() {
+    this.getType().(IntegralType).isUnsigned() and
+    // Avoid overlap. It should be slightly cheaper to analyze
+    // `MulByConstantExpr`.
+    not this instanceof MulByConstantExpr
+  }
+}
+
+/**
+ * Holds if `expr` is effectively a multiplication of `operand` with the
+ * positive constant `positive`.
+ */
+private predicate effectivelyMultipliesByPositive(Expr expr, Expr operand, float positive) {
+  operand = expr.(MulByConstantExpr).getOperand() and
+  positive = expr.(MulByConstantExpr).getConstant() and
+  positive >= 0.0 // includes positive zero
+  or
+  operand = expr.(UnaryPlusExpr).getOperand() and
+  positive = 1.0
+  or
+  operand = expr.(CommaExpr).getRightOperand() and
+  positive = 1.0
+  or
+  operand = expr.(StmtExpr).getResultExpr() and
+  positive = 1.0
+}
+
+/**
+ * Holds if `expr` is effectively a multiplication of `operand` with the
+ * negative constant `negative`.
+ */
+private predicate effectivelyMultipliesByNegative(Expr expr, Expr operand, float negative) {
+  operand = expr.(MulByConstantExpr).getOperand() and
+  negative = expr.(MulByConstantExpr).getConstant() and
+  negative < 0.0 // includes negative zero
+  or
+  operand = expr.(UnaryMinusExpr).getOperand() and
+  negative = -1.0
+}
+
+private class AssignMulByConstantExpr extends AssignMulExpr {
+  float constant;
+
+  AssignMulByConstantExpr() { constant = getValue(this.getRValue().getFullyConverted()).toFloat() }
+
+  float getConstant() { result = constant }
+}
+
+private class AssignMulByPositiveConstantExpr extends AssignMulByConstantExpr {
+  AssignMulByPositiveConstantExpr() { constant >= 0.0 }
+}
+
+private class AssignMulByNegativeConstantExpr extends AssignMulByConstantExpr {
+  AssignMulByNegativeConstantExpr() { constant < 0.0 }
+}
+
+private class UnsignedAssignMulExpr extends AssignMulExpr {
+  UnsignedAssignMulExpr() {
+    this.getType().(IntegralType).isUnsigned() and
+    // Avoid overlap. It should be slightly cheaper to analyze
+    // `AssignMulByConstantExpr`.
+    not this instanceof AssignMulByConstantExpr
+  }
+}
+
 /** Set of expressions which we know how to analyze. */
 private predicate analyzableExpr(Expr e) {
   // The type of the expression must be arithmetic. We reuse the logic in
@@ -164,9 +251,9 @@ private predicate analyzableExpr(Expr e) {
   (
     exists(getValue(e).toFloat())
     or
-    e instanceof UnaryPlusExpr
+    effectivelyMultipliesByPositive(e, _, _)
     or
-    e instanceof UnaryMinusExpr
+    effectivelyMultipliesByNegative(e, _, _)
     or
     e instanceof MinExpr
     or
@@ -178,20 +265,22 @@ private predicate analyzableExpr(Expr e) {
     or
     e instanceof SubExpr
     or
+    e instanceof UnsignedMulExpr
+    or
     e instanceof AssignExpr
     or
     e instanceof AssignAddExpr
     or
     e instanceof AssignSubExpr
     or
+    e instanceof UnsignedAssignMulExpr
+    or
+    e instanceof AssignMulByConstantExpr
+    or
     e instanceof CrementOperation
     or
     e instanceof RemExpr
     or
-    e instanceof CommaExpr
-    or
-    e instanceof StmtExpr
-    or
     // A conversion is analyzable, provided that its child has an arithmetic
     // type. (Sometimes the child is a reference type, and so does not get
     // any bounds.) Rather than checking whether the type of the child is
@@ -206,7 +295,10 @@ private predicate analyzableExpr(Expr e) {
     e instanceof UnsignedBitwiseAndExpr
     or
     // `>>` by a constant
-    exists(e.(RShiftExpr).getRightOperand().getValue())
+    exists(getValue(e.(RShiftExpr).getRightOperand()))
+    or
+    // A modeled expression for range analysis
+    e instanceof SimpleRangeAnalysisExpr
   )
 }
 
@@ -227,25 +319,33 @@ private predicate defDependsOnDef(
   // Definitions with a defining value.
   exists(Expr expr | assignmentDef(def, v, expr) | exprDependsOnDef(expr, srcDef, srcVar))
   or
-  exists(AssignAddExpr assignAdd, RangeSsaDefinition nextDef |
+  exists(AssignAddExpr assignAdd |
     def = assignAdd and
-    assignAdd.getLValue() = nextDef.getAUse(v)
-  |
-    defDependsOnDef(nextDef, v, srcDef, srcVar) or
-    exprDependsOnDef(assignAdd.getRValue(), srcDef, srcVar)
+    def.getAVariable() = v and
+    exprDependsOnDef(assignAdd.getAnOperand(), srcDef, srcVar)
   )
   or
-  exists(AssignSubExpr assignSub, RangeSsaDefinition nextDef |
+  exists(AssignSubExpr assignSub |
     def = assignSub and
-    assignSub.getLValue() = nextDef.getAUse(v)
-  |
-    defDependsOnDef(nextDef, v, srcDef, srcVar) or
-    exprDependsOnDef(assignSub.getRValue(), srcDef, srcVar)
+    def.getAVariable() = v and
+    exprDependsOnDef(assignSub.getAnOperand(), srcDef, srcVar)
+  )
+  or
+  exists(UnsignedAssignMulExpr assignMul |
+    def = assignMul and
+    def.getAVariable() = v and
+    exprDependsOnDef(assignMul.getAnOperand(), srcDef, srcVar)
+  )
+  or
+  exists(AssignMulByConstantExpr assignMul |
+    def = assignMul and
+    def.getAVariable() = v and
+    exprDependsOnDef(assignMul.getLValue(), srcDef, srcVar)
   )
   or
   exists(CrementOperation crem |
     def = crem and
-    crem.getOperand() = v.getAnAccess() and
+    def.getAVariable() = v and
     exprDependsOnDef(crem.getOperand(), srcDef, srcVar)
   )
   or
@@ -258,12 +358,14 @@ private predicate defDependsOnDef(
  * the structure of `getLowerBoundsImpl` and `getUpperBoundsImpl`.
  */
 private predicate exprDependsOnDef(Expr e, RangeSsaDefinition srcDef, StackVariable srcVar) {
-  exists(UnaryMinusExpr negateExpr | e = negateExpr |
-    exprDependsOnDef(negateExpr.getOperand(), srcDef, srcVar)
+  exists(Expr operand |
+    effectivelyMultipliesByNegative(e, operand, _) and
+    exprDependsOnDef(operand, srcDef, srcVar)
   )
   or
-  exists(UnaryPlusExpr plusExpr | e = plusExpr |
-    exprDependsOnDef(plusExpr.getOperand(), srcDef, srcVar)
+  exists(Expr operand |
+    effectivelyMultipliesByPositive(e, operand, _) and
+    exprDependsOnDef(operand, srcDef, srcVar)
   )
   or
   exists(MinExpr minExpr | e = minExpr | exprDependsOnDef(minExpr.getAnOperand(), srcDef, srcVar))
@@ -278,6 +380,10 @@ private predicate exprDependsOnDef(Expr e, RangeSsaDefinition srcDef, StackVaria
   or
   exists(SubExpr subExpr | e = subExpr | exprDependsOnDef(subExpr.getAnOperand(), srcDef, srcVar))
   or
+  exists(UnsignedMulExpr mulExpr | e = mulExpr |
+    exprDependsOnDef(mulExpr.getAnOperand(), srcDef, srcVar)
+  )
+  or
   exists(AssignExpr addExpr | e = addExpr | exprDependsOnDef(addExpr.getRValue(), srcDef, srcVar))
   or
   exists(AssignAddExpr addExpr | e = addExpr |
@@ -288,20 +394,20 @@ private predicate exprDependsOnDef(Expr e, RangeSsaDefinition srcDef, StackVaria
     exprDependsOnDef(subExpr.getAnOperand(), srcDef, srcVar)
   )
   or
+  exists(UnsignedAssignMulExpr mulExpr | e = mulExpr |
+    exprDependsOnDef(mulExpr.getAnOperand(), srcDef, srcVar)
+  )
+  or
+  exists(AssignMulByConstantExpr mulExpr | e = mulExpr |
+    exprDependsOnDef(mulExpr.getLValue(), srcDef, srcVar)
+  )
+  or
   exists(CrementOperation crementExpr | e = crementExpr |
     exprDependsOnDef(crementExpr.getOperand(), srcDef, srcVar)
   )
   or
   exists(RemExpr remExpr | e = remExpr | exprDependsOnDef(remExpr.getAnOperand(), srcDef, srcVar))
   or
-  exists(CommaExpr commaExpr | e = commaExpr |
-    exprDependsOnDef(commaExpr.getRightOperand(), srcDef, srcVar)
-  )
-  or
-  exists(StmtExpr stmtExpr | e = stmtExpr |
-    exprDependsOnDef(stmtExpr.getResultExpr(), srcDef, srcVar)
-  )
-  or
   exists(Conversion convExpr | e = convExpr | exprDependsOnDef(convExpr.getExpr(), srcDef, srcVar))
   or
   // unsigned `&`
@@ -313,11 +419,21 @@ private predicate exprDependsOnDef(Expr e, RangeSsaDefinition srcDef, StackVaria
   // `>>` by a constant
   exists(RShiftExpr rs |
     rs = e and
-    exists(rs.getRightOperand().getValue()) and
+    exists(getValue(rs.getRightOperand())) and
     exprDependsOnDef(rs.getLeftOperand(), srcDef, srcVar)
   )
   or
   e = srcDef.getAUse(srcVar)
+  or
+  // A modeled expression for range analysis
+  exists(SimpleRangeAnalysisExpr rae | rae = e |
+    rae.dependsOnDef(srcDef, srcVar)
+    or
+    exists(Expr child |
+      rae.dependsOnChild(child) and
+      exprDependsOnDef(child, srcDef, srcVar)
+    )
+  )
 }
 
 /**
@@ -381,9 +497,17 @@ private predicate assignmentDef(RangeSsaDefinition def, StackVariable v, Expr ex
   )
 }
 
-/** See comment above sourceDef. */
+/** See comment above assignmentDef. */
 private predicate analyzableDef(RangeSsaDefinition def, StackVariable v) {
-  assignmentDef(def, v, _) or defDependsOnDef(def, v, _, _)
+  assignmentDef(def, v, _)
+  or
+  analyzableExpr(def.(AssignOperation)) and
+  v = def.getAVariable()
+  or
+  analyzableExpr(def.(CrementOperation)) and
+  v = def.getAVariable()
+  or
+  phiDependsOnDef(def, v, _, _)
 }
 
 /**
@@ -435,13 +559,6 @@ private float addRoundingDownSmall(float x, float small) {
   if (x + small) - x > small then result = (x + small).nextDown() else result = (x + small)
 }
 
-/**
- * Gets the truncated lower bounds of the fully converted expression.
- */
-private float getFullyConvertedLowerBounds(Expr expr) {
-  result = getTruncatedLowerBounds(expr.getFullyConverted())
-}
-
 /**
  * Gets the lower bounds of the expression.
  *
@@ -488,13 +605,6 @@ private float getTruncatedLowerBounds(Expr expr) {
     result = exprMinVal(expr)
 }
 
-/**
- * Gets the truncated upper bounds of the fully converted expression.
- */
-private float getFullyConvertedUpperBounds(Expr expr) {
-  result = getTruncatedUpperBounds(expr.getFullyConverted())
-}
-
 /**
  * Gets the upper bounds of the expression.
  *
@@ -562,15 +672,16 @@ deprecated predicate positive_overflow(Expr expr) { exprMightOverflowPositively(
 
 /** Only to be called by `getTruncatedLowerBounds`. */
 private float getLowerBoundsImpl(Expr expr) {
-  exists(UnaryPlusExpr plusExpr |
-    expr = plusExpr and
-    result = getFullyConvertedLowerBounds(plusExpr.getOperand())
+  exists(Expr operand, float operandLow, float positive |
+    effectivelyMultipliesByPositive(expr, operand, positive) and
+    operandLow = getFullyConvertedLowerBounds(operand) and
+    result = positive * operandLow
   )
   or
-  exists(UnaryMinusExpr negateExpr, float xHigh |
-    expr = negateExpr and
-    xHigh = getFullyConvertedUpperBounds(negateExpr.getOperand()) and
-    result = -xHigh
+  exists(Expr operand, float operandHigh, float negative |
+    effectivelyMultipliesByNegative(expr, operand, negative) and
+    operandHigh = getFullyConvertedUpperBounds(operand) and
+    result = negative * operandHigh
   )
   or
   exists(MinExpr minExpr |
@@ -625,6 +736,13 @@ private float getLowerBoundsImpl(Expr expr) {
     result = addRoundingDown(xLow, -yHigh)
   )
   or
+  exists(UnsignedMulExpr mulExpr, float xLow, float yLow |
+    expr = mulExpr and
+    xLow = getFullyConvertedLowerBounds(mulExpr.getLeftOperand()) and
+    yLow = getFullyConvertedLowerBounds(mulExpr.getRightOperand()) and
+    result = xLow * yLow
+  )
+  or
   exists(AssignExpr assign |
     expr = assign and
     result = getFullyConvertedLowerBounds(assign.getRValue())
@@ -644,6 +762,25 @@ private float getLowerBoundsImpl(Expr expr) {
     result = addRoundingDown(xLow, -yHigh)
   )
   or
+  exists(UnsignedAssignMulExpr mulExpr, float xLow, float yLow |
+    expr = mulExpr and
+    xLow = getFullyConvertedLowerBounds(mulExpr.getLValue()) and
+    yLow = getFullyConvertedLowerBounds(mulExpr.getRValue()) and
+    result = xLow * yLow
+  )
+  or
+  exists(AssignMulByPositiveConstantExpr mulExpr, float xLow |
+    expr = mulExpr and
+    xLow = getFullyConvertedLowerBounds(mulExpr.getLValue()) and
+    result = xLow * mulExpr.getConstant()
+  )
+  or
+  exists(AssignMulByNegativeConstantExpr mulExpr, float xHigh |
+    expr = mulExpr and
+    xHigh = getFullyConvertedUpperBounds(mulExpr.getLValue()) and
+    result = xHigh * mulExpr.getConstant()
+  )
+  or
   exists(PrefixIncrExpr incrExpr, float xLow |
     expr = incrExpr and
     xLow = getFullyConvertedLowerBounds(incrExpr.getOperand()) and
@@ -688,16 +825,6 @@ private float getLowerBoundsImpl(Expr expr) {
     )
   )
   or
-  exists(CommaExpr commaExpr |
-    expr = commaExpr and
-    result = getFullyConvertedLowerBounds(commaExpr.getRightOperand())
-  )
-  or
-  exists(StmtExpr stmtExpr |
-    expr = stmtExpr and
-    result = getFullyConvertedLowerBounds(stmtExpr.getResultExpr())
-  )
-  or
   // If the conversion is to an arithmetic type then we just return the
   // lower bound of the child. We do not need to handle truncation and
   // overflow here, because that is done in `getTruncatedLowerBounds`.
@@ -711,7 +838,9 @@ private float getLowerBoundsImpl(Expr expr) {
   or
   // Use SSA to get the lower bounds for a variable use.
   exists(RangeSsaDefinition def, StackVariable v | expr = def.getAUse(v) |
-    result = getDefLowerBounds(def, v)
+    result = getDefLowerBounds(def, v) and
+    // Not explicitly modeled by a SimpleRangeAnalysisExpr
+    not expr instanceof SimpleRangeAnalysisExpr
   )
   or
   // unsigned `&` (tighter bounds may exist)
@@ -724,22 +853,29 @@ private float getLowerBoundsImpl(Expr expr) {
   exists(RShiftExpr rsExpr, float left, int right |
     rsExpr = expr and
     left = getFullyConvertedLowerBounds(rsExpr.getLeftOperand()) and
-    right = rsExpr.getRightOperand().getFullyConverted().getValue().toInt() and
+    right = getValue(rsExpr.getRightOperand().getFullyConverted()).toInt() and
     result = safeFloor(left / 2.pow(right))
   )
+  or
+  // A modeled expression for range analysis
+  exists(SimpleRangeAnalysisExpr rangeAnalysisExpr |
+    rangeAnalysisExpr = expr and
+    result = rangeAnalysisExpr.getLowerBounds()
+  )
 }
 
 /** Only to be called by `getTruncatedUpperBounds`. */
 private float getUpperBoundsImpl(Expr expr) {
-  exists(UnaryPlusExpr plusExpr |
-    expr = plusExpr and
-    result = getFullyConvertedUpperBounds(plusExpr.getOperand())
+  exists(Expr operand, float operandHigh, float positive |
+    effectivelyMultipliesByPositive(expr, operand, positive) and
+    operandHigh = getFullyConvertedUpperBounds(operand) and
+    result = positive * operandHigh
   )
   or
-  exists(UnaryMinusExpr negateExpr, float xLow |
-    expr = negateExpr and
-    xLow = getFullyConvertedLowerBounds(negateExpr.getOperand()) and
-    result = -xLow
+  exists(Expr operand, float operandLow, float negative |
+    effectivelyMultipliesByNegative(expr, operand, negative) and
+    operandLow = getFullyConvertedLowerBounds(operand) and
+    result = negative * operandLow
   )
   or
   exists(MaxExpr maxExpr |
@@ -794,6 +930,13 @@ private float getUpperBoundsImpl(Expr expr) {
     result = addRoundingUp(xHigh, -yLow)
   )
   or
+  exists(UnsignedMulExpr mulExpr, float xHigh, float yHigh |
+    expr = mulExpr and
+    xHigh = getFullyConvertedUpperBounds(mulExpr.getLeftOperand()) and
+    yHigh = getFullyConvertedUpperBounds(mulExpr.getRightOperand()) and
+    result = xHigh * yHigh
+  )
+  or
   exists(AssignExpr assign |
     expr = assign and
     result = getFullyConvertedUpperBounds(assign.getRValue())
@@ -813,6 +956,25 @@ private float getUpperBoundsImpl(Expr expr) {
     result = addRoundingUp(xHigh, -yLow)
   )
   or
+  exists(UnsignedAssignMulExpr mulExpr, float xHigh, float yHigh |
+    expr = mulExpr and
+    xHigh = getFullyConvertedUpperBounds(mulExpr.getLValue()) and
+    yHigh = getFullyConvertedUpperBounds(mulExpr.getRValue()) and
+    result = xHigh * yHigh
+  )
+  or
+  exists(AssignMulByPositiveConstantExpr mulExpr, float xHigh |
+    expr = mulExpr and
+    xHigh = getFullyConvertedUpperBounds(mulExpr.getLValue()) and
+    result = xHigh * mulExpr.getConstant()
+  )
+  or
+  exists(AssignMulByNegativeConstantExpr mulExpr, float xLow |
+    expr = mulExpr and
+    xLow = getFullyConvertedLowerBounds(mulExpr.getLValue()) and
+    result = xLow * mulExpr.getConstant()
+  )
+  or
   exists(PrefixIncrExpr incrExpr, float xHigh |
     expr = incrExpr and
     xHigh = getFullyConvertedUpperBounds(incrExpr.getOperand()) and
@@ -855,16 +1017,6 @@ private float getUpperBoundsImpl(Expr expr) {
     )
   )
   or
-  exists(CommaExpr commaExpr |
-    expr = commaExpr and
-    result = getFullyConvertedUpperBounds(commaExpr.getRightOperand())
-  )
-  or
-  exists(StmtExpr stmtExpr |
-    expr = stmtExpr and
-    result = getFullyConvertedUpperBounds(stmtExpr.getResultExpr())
-  )
-  or
   // If the conversion is to an arithmetic type then we just return the
   // upper bound of the child. We do not need to handle truncation and
   // overflow here, because that is done in `getTruncatedUpperBounds`.
@@ -878,7 +1030,9 @@ private float getUpperBoundsImpl(Expr expr) {
   or
   // Use SSA to get the upper bounds for a variable use.
   exists(RangeSsaDefinition def, StackVariable v | expr = def.getAUse(v) |
-    result = getDefUpperBounds(def, v)
+    result = getDefUpperBounds(def, v) and
+    // Not explicitly modeled by a SimpleRangeAnalysisExpr
+    not expr instanceof SimpleRangeAnalysisExpr
   )
   or
   // unsigned `&` (tighter bounds may exist)
@@ -893,9 +1047,15 @@ private float getUpperBoundsImpl(Expr expr) {
   exists(RShiftExpr rsExpr, float left, int right |
     rsExpr = expr and
     left = getFullyConvertedUpperBounds(rsExpr.getLeftOperand()) and
-    right = rsExpr.getRightOperand().getFullyConverted().getValue().toInt() and
+    right = getValue(rsExpr.getRightOperand().getFullyConverted()).toInt() and
     result = safeFloor(left / 2.pow(right))
   )
+  or
+  // A modeled expression for range analysis
+  exists(SimpleRangeAnalysisExpr rangeAnalysisExpr |
+    rangeAnalysisExpr = expr and
+    result = rangeAnalysisExpr.getUpperBounds()
+  )
 }
 
 /**
@@ -1041,6 +1201,28 @@ private float getDefLowerBoundsImpl(RangeSsaDefinition def, StackVariable v) {
     result = addRoundingDown(lhsLB, -rhsUB)
   )
   or
+  exists(UnsignedAssignMulExpr assignMul, RangeSsaDefinition nextDef, float lhsLB, float rhsLB |
+    def = assignMul and
+    assignMul.getLValue() = nextDef.getAUse(v) and
+    lhsLB = getDefLowerBounds(nextDef, v) and
+    rhsLB = getFullyConvertedLowerBounds(assignMul.getRValue()) and
+    result = lhsLB * rhsLB
+  )
+  or
+  exists(AssignMulByPositiveConstantExpr assignMul, RangeSsaDefinition nextDef, float lhsLB |
+    def = assignMul and
+    assignMul.getLValue() = nextDef.getAUse(v) and
+    lhsLB = getDefLowerBounds(nextDef, v) and
+    result = lhsLB * assignMul.getConstant()
+  )
+  or
+  exists(AssignMulByNegativeConstantExpr assignMul, RangeSsaDefinition nextDef, float lhsUB |
+    def = assignMul and
+    assignMul.getLValue() = nextDef.getAUse(v) and
+    lhsUB = getDefUpperBounds(nextDef, v) and
+    result = lhsUB * assignMul.getConstant()
+  )
+  or
   exists(IncrementOperation incr, float newLB |
     def = incr and
     incr.getOperand() = v.getAnAccess() and
@@ -1083,6 +1265,28 @@ private float getDefUpperBoundsImpl(RangeSsaDefinition def, StackVariable v) {
     result = addRoundingUp(lhsUB, -rhsLB)
   )
   or
+  exists(UnsignedAssignMulExpr assignMul, RangeSsaDefinition nextDef, float lhsUB, float rhsUB |
+    def = assignMul and
+    assignMul.getLValue() = nextDef.getAUse(v) and
+    lhsUB = getDefUpperBounds(nextDef, v) and
+    rhsUB = getFullyConvertedUpperBounds(assignMul.getRValue()) and
+    result = lhsUB * rhsUB
+  )
+  or
+  exists(AssignMulByPositiveConstantExpr assignMul, RangeSsaDefinition nextDef, float lhsUB |
+    def = assignMul and
+    assignMul.getLValue() = nextDef.getAUse(v) and
+    lhsUB = getDefUpperBounds(nextDef, v) and
+    result = lhsUB * assignMul.getConstant()
+  )
+  or
+  exists(AssignMulByNegativeConstantExpr assignMul, RangeSsaDefinition nextDef, float lhsLB |
+    def = assignMul and
+    assignMul.getLValue() = nextDef.getAUse(v) and
+    lhsLB = getDefLowerBounds(nextDef, v) and
+    result = lhsLB * assignMul.getConstant()
+  )
+  or
   exists(IncrementOperation incr, float newUB |
     def = incr and
     incr.getOperand() = v.getAnAccess() and
@@ -1480,3 +1684,25 @@ private module SimpleRangeAnalysisCached {
     convertedExprMightOverflowPositively(expr)
   }
 }
+
+/**
+ * INTERNAL: do not use. This module contains utilities for use in the
+ * experimental `SimpleRangeAnalysisExpr` module.
+ */
+module SimpleRangeAnalysisInternal {
+  /**
+   * Gets the truncated lower bounds of the fully converted expression.
+   */
+  float getFullyConvertedLowerBounds(Expr expr) {
+    result = getTruncatedLowerBounds(expr.getFullyConverted())
+  }
+
+  /**
+   * Gets the truncated upper bounds of the fully converted expression.
+   */
+  float getFullyConvertedUpperBounds(Expr expr) {
+    result = getTruncatedUpperBounds(expr.getFullyConverted())
+  }
+}
+
+private import SimpleRangeAnalysisInternal

cpp/ql/test/experimental/library-tests/rangeanalysis/extensibility/extensibility.c

@@ -0,0 +1,9 @@
+/// Adds its arguments (has custom modeling in QL)
+int custom_add_function(int a, int b);
+
+int test_extensibility_add(int x) {
+  if (x >= -10 && x <= 10) {
+    int result = custom_add_function(x, 100);
+    return result; // 90 .. 110
+  }
+}

cpp/ql/test/experimental/library-tests/rangeanalysis/extensibility/extensibility.expected

@@ -0,0 +1,4 @@
+| extensibility.c:5:7:5:7 | x | -2.147483648E9 | 2.147483647E9 |
+| extensibility.c:5:19:5:19 | x | -10.0 | 2.147483647E9 |
+| extensibility.c:6:38:6:38 | x | -10.0 | 10.0 |
+| extensibility.c:7:12:7:17 | result | 90.0 | 110.0 |

cpp/ql/test/experimental/library-tests/rangeanalysis/extensibility/extensibility.ql

@@ -0,0 +1,32 @@
+import semmle.code.cpp.rangeanalysis.SimpleRangeAnalysis
+import experimental.semmle.code.cpp.models.interfaces.SimpleRangeAnalysisExpr
+
+class CustomAddFunctionCall extends SimpleRangeAnalysisExpr, FunctionCall {
+  CustomAddFunctionCall() { this.getTarget().hasGlobalName("custom_add_function") }
+
+  override float getLowerBounds() {
+    exists(float lower0, float lower1 |
+      lower0 = getFullyConvertedLowerBounds(this.getArgument(0)) and
+      lower1 = getFullyConvertedLowerBounds(this.getArgument(1)) and
+      // Note: this rounds toward 0, not -Inf as it should
+      result = lower0 + lower1
+    )
+  }
+
+  override float getUpperBounds() {
+    exists(float upper0, float upper1 |
+      upper0 = getFullyConvertedUpperBounds(this.getArgument(0)) and
+      upper1 = getFullyConvertedUpperBounds(this.getArgument(1)) and
+      // Note: this rounds toward 0, not Inf as it should
+      result = upper0 + upper1
+    )
+  }
+
+  override predicate dependsOnChild(Expr child) { child = this.getAnArgument() }
+}
+
+from VariableAccess expr, float lower, float upper
+where
+  lower = lowerBound(expr) and
+  upper = upperBound(expr)
+select expr, lower, upper

cpp/ql/test/experimental/query-tests/Security/CWE/CWE-359/semmle/tests/PrivateCleartextWrite.expected

@@ -0,0 +1,21 @@
+edges
+| test.cpp:77:16:77:22 | medical | test.cpp:78:24:78:27 | temp |
+| test.cpp:81:17:81:20 | call to func | test.cpp:82:24:82:28 | buff5 |
+| test.cpp:81:22:81:28 | medical | test.cpp:81:17:81:20 | call to func |
+nodes
+| test.cpp:57:9:57:18 | theZipcode | semmle.label | theZipcode |
+| test.cpp:74:24:74:30 | medical | semmle.label | medical |
+| test.cpp:77:16:77:22 | medical | semmle.label | medical |
+| test.cpp:78:24:78:27 | temp | semmle.label | temp |
+| test.cpp:81:17:81:20 | call to func | semmle.label | call to func |
+| test.cpp:81:22:81:28 | medical | semmle.label | medical |
+| test.cpp:82:24:82:28 | buff5 | semmle.label | buff5 |
+| test.cpp:96:37:96:46 | theZipcode | semmle.label | theZipcode |
+| test.cpp:99:42:99:51 | theZipcode | semmle.label | theZipcode |
+#select
+| test.cpp:57:9:57:18 | theZipcode | This write into the external location 'theZipcode' may contain unencrypted data from $@ | test.cpp:57:9:57:18 | theZipcode | this source. |
+| test.cpp:74:24:74:30 | medical | This write into the external location 'medical' may contain unencrypted data from $@ | test.cpp:74:24:74:30 | medical | this source. |
+| test.cpp:78:24:78:27 | temp | This write into the external location 'temp' may contain unencrypted data from $@ | test.cpp:77:16:77:22 | medical | this source. |
+| test.cpp:82:24:82:28 | buff5 | This write into the external location 'buff5' may contain unencrypted data from $@ | test.cpp:81:22:81:28 | medical | this source. |
+| test.cpp:96:37:96:46 | theZipcode | This write into the external location 'theZipcode' may contain unencrypted data from $@ | test.cpp:96:37:96:46 | theZipcode | this source. |
+| test.cpp:99:42:99:51 | theZipcode | This write into the external location 'theZipcode' may contain unencrypted data from $@ | test.cpp:99:42:99:51 | theZipcode | this source. |

cpp/ql/test/experimental/query-tests/Security/CWE/CWE-359/semmle/tests/PrivateCleartextWrite.qlref

@@ -0,0 +1 @@
+experimental/Security/CWE/CWE-359/PrivateCleartextWrite.ql

cpp/ql/test/experimental/query-tests/Security/CWE/CWE-359/semmle/tests/test.cpp

@@ -0,0 +1,105 @@
+#define FILE int
+#define wchar char
+#define size_t int
+typedef int streamsize;
+
+size_t fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream);
+int fputs(const char *s, FILE *stream);
+int fputc(int c, FILE *stream);
+int fprintf(FILE *stream, const char *format, ...);
+int sprintf(char *s, const char *format, ...);
+size_t strlen(const char *s);
+
+namespace std
+{
+  template <class charT>
+  struct char_traits;
+
+  template <class charT, class traits = char_traits<charT>>
+  class basic_ostream /*: virtual public basic_ios<charT,traits> - not needed for this test */
+  {
+  public:
+    typedef charT char_type;
+    basic_ostream<charT, traits> &write(const char_type *s, streamsize n);
+  };
+
+  template <class charT, class traits = char_traits<charT>>
+  class basic_ofstream : public basic_ostream<charT, traits>
+  {
+  public:
+  };
+
+  template <class charT, class traits>
+  basic_ostream<charT, traits> &operator<<(basic_ostream<charT, traits> &, const charT *);
+
+  typedef basic_ostream<char> ostream;
+  typedef basic_ofstream<char> ofstream;
+}; // namespace std
+
+using namespace std;
+
+char *encrypt(char *buffer)
+{
+  return buffer;
+}
+char *func(char *buffer)
+{
+  return buffer;
+}
+
+// test for CleartextFileWrite
+void file()
+{
+  char *theZipcode = "cleartext zipcode!";
+  FILE *file;
+
+  // BAD: write zipcode to file in cleartext
+  fputs(theZipcode, file);
+
+  // GOOD: encrypt first
+  char *encrypted = encrypt(theZipcode);
+  fwrite(encrypted, sizeof(encrypted), 1, file);
+}
+
+// test for CleartextBufferWrite
+int main(int argc, char **argv)
+{
+  char *medical = "medical";
+  char *buff1;
+  char *buff2;
+  char *buff3;
+  char *buff4;
+
+  // BAD: write medical to buffer in cleartext
+  sprintf(buff1, "%s", medical);
+
+  // BAD: write medical to buffer in cleartext
+  char *temp = medical;
+  sprintf(buff2, "%s", temp);
+
+  // BAD: write medical to buffer in cleartext
+  char *buff5 = func(medical);
+  sprintf(buff3, "%s", buff5);
+
+  char *buff6 = encrypt(medical);
+  // GOOD: encrypt first
+  sprintf(buff4, "%s", buff6);
+}
+
+// test for CleartextFileWrite
+void stream()
+{
+  char *theZipcode = "cleartext zipcode!";
+  ofstream mystream;
+
+  // BAD: write zipcode to file in cleartext
+  mystream << "the zipcode is: " << theZipcode;
+
+  // BAD: write zipcode to file in cleartext
+  (mystream << "the zipcode is: ").write(theZipcode, strlen(theZipcode));
+
+  // GOOD: encrypt first
+  char *encrypted = encrypt(theZipcode);
+  mystream << "the zipcode is: " << encrypted;
+  (mystream << "the zipcode is: ").write(encrypted, strlen(encrypted));
+}

cpp/ql/test/experimental/query-tests/Security/CWE/semmle/tests/MemoryUnsafeFunctionScan.cpp

@@ -0,0 +1,25 @@
+///// Library routines /////
+
+int scanf(const char *format, ...);
+int sscanf(const char *str, const char *format, ...);
+int fscanf(const char *str, const char *format, ...);
+
+///// Test code /////
+
+int main(int argc, char **argv)
+{
+
+    // BAD, do not use scanf without specifying a length first
+    char buf1[10];
+    scanf("%s", buf1);
+
+    // GOOD, length is specified
+    char buf2[10];
+    sscanf(buf2, "%9s");
+
+    // BAD, do not use scanf without specifying a length first
+    char file[10];
+    fscanf(file, "%s", buf2);
+
+    return 0;
+}

cpp/ql/test/experimental/query-tests/Security/CWE/semmle/tests/MemoryUnsafeFunctionScan.expected

@@ -0,0 +1,2 @@
+| MemoryUnsafeFunctionScan.cpp:14:5:14:9 | call to scanf | Dangerous use of one of the scanf functions |
+| MemoryUnsafeFunctionScan.cpp:22:5:22:10 | call to fscanf | Dangerous use of one of the scanf functions |

cpp/ql/test/experimental/query-tests/Security/CWE/semmle/tests/MemoryUnsafeFunctionScan.qlref

@@ -0,0 +1 @@
+experimental/Security/CWE/CWE-120/MemoryUnsafeFunctionScan.ql

cpp/ql/test/library-tests/dataflow/taint-tests/stl.cpp

@@ -1,310 +0,0 @@
-
-typedef unsigned long size_t;
-
-namespace std
-{
-	template<class charT> struct char_traits;
-
-	typedef size_t streamsize;
-
-	struct ptrdiff_t;
-
-	template <class iterator_category,
-			  class value_type,
-			  class difference_type = ptrdiff_t,
-			  class pointer_type = value_type*,
-			  class reference_type = value_type&>
-	struct iterator {
-		iterator &operator++();
-		iterator operator++(int);
-		bool operator==(iterator other) const;
-		bool operator!=(iterator other) const;
-		reference_type operator*() const;
-	};
-
-	struct input_iterator_tag {};
-	struct forward_iterator_tag : public input_iterator_tag {};
-	struct bidirectional_iterator_tag : public forward_iterator_tag {};
-	struct random_access_iterator_tag : public bidirectional_iterator_tag {};
-
-	template <class T> class allocator {
-	public:
-		allocator() throw();
-	};
-	
-	template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
-	class basic_string {
-	public:
-		explicit basic_string(const Allocator& a = Allocator());
-		basic_string(const charT* s, const Allocator& a = Allocator());
-
-		const charT* c_str() const;
-
-		typedef std::iterator<random_access_iterator_tag, charT> iterator;
-		typedef std::iterator<random_access_iterator_tag, const charT> const_iterator;
-
-		iterator begin();
-		iterator end();
-		const_iterator begin() const;
-		const_iterator end() const;
-		const_iterator cbegin() const;
-		const_iterator cend() const;
-	};
-
-	typedef basic_string<char> string;
-
-	template <class charT, class traits = char_traits<charT> >
-	class basic_istream /*: virtual public basic_ios<charT,traits> - not needed for this test */ {
-	public:
-		basic_istream<charT,traits>& operator>>(int& n);
-	};
-
-	template <class charT, class traits = char_traits<charT> >
-	class basic_ostream /*: virtual public basic_ios<charT,traits> - not needed for this test */ {
-	public:
-		typedef charT char_type;
-		basic_ostream<charT,traits>& write(const char_type* s, streamsize n);
-
-		basic_ostream<charT, traits>& operator<<(int n);
-	};
-
-	template<class charT, class traits> basic_ostream<charT,traits>& operator<<(basic_ostream<charT,traits>&, const charT*);
-	template<class charT, class traits, class Allocator> basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>& os, const basic_string<charT, traits, Allocator>& str); 
-
-	template<class charT, class traits = char_traits<charT>>
-	class basic_iostream : public basic_istream<charT, traits>, public basic_ostream<charT, traits> {
-	public:
-	};
-
-	template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT>>
-	class basic_stringstream : public basic_iostream<charT, traits> {
-	public:
-		explicit basic_stringstream(/*ios_base::openmode which = ios_base::out|ios_base::in - not needed for this test*/);
-
-		basic_string<charT, traits, Allocator> str() const;
-	};
-
-	using stringstream = basic_stringstream<char>;
-}
-
-char *source();
-void sink(const char *s) {};
-void sink(const std::string &s) {};
-void sink(const std::stringstream &s) {};
-
-void test_string()
-{
-	char *a = source();
-	std::string b("123");
-	std::string c(source());
-
-	sink(a); // tainted
-	sink(b);
-	sink(c); // tainted
-	sink(b.c_str());
-	sink(c.c_str()); // tainted
-}
-
-void test_stringstream()
-{
-	std::stringstream ss1, ss2, ss3, ss4, ss5;
-	std::string t(source());
-
-	ss1 << "1234";
-	ss2 << source();
-	ss3 << "123" << source();
-	ss4 << source() << "456";
-	ss5 << t;
-
-	sink(ss1);
-	sink(ss2); // tainted [NOT DETECTED]
-	sink(ss3); // tainted [NOT DETECTED]
-	sink(ss4); // tainted [NOT DETECTED]
-	sink(ss5); // tainted [NOT DETECTED]
-	sink(ss1.str());
-	sink(ss2.str()); // tainted [NOT DETECTED]
-	sink(ss3.str()); // tainted [NOT DETECTED]
-	sink(ss4.str()); // tainted [NOT DETECTED]
-	sink(ss5.str()); // tainted [NOT DETECTED]
-}
-
-void test_stringstream_int(int source)
-{
-	std::stringstream ss1, ss2;
-
-	ss1 << 1234;
-	ss2 << source;
-
-	sink(ss1);
-	sink(ss2); // tainted [NOT DETECTED]
-	sink(ss1.str());
-	sink(ss2.str()); // tainted [NOT DETECTED]
-}
-
-using namespace std;
-
-char *user_input() {
-  return source();
-}
-
-void sink(const char *filename, const char *mode);
-
-void test_strings2()
-{
-	string path1 = user_input();
-	sink(path1.c_str(), "r"); // tainted
-
-	string path2;
-	path2 = user_input();
-	sink(path2.c_str(), "r"); // tainted
-
-	string path3(user_input());
-	sink(path3.c_str(), "r"); // tainted
-}
-
-void test_string3()
-{
-	const char *cs = source();
-
-	// convert char * -> std::string
-	std::string ss(cs);
-
-	sink(cs); // tainted
-	sink(ss); // tainted
-}
-
-void test_string4()
-{
-	const char *cs = source();
-
-	// convert char * -> std::string
-	std::string ss(cs);
-
-	// convert back std::string -> char *
-	cs = ss.c_str();
-
-	sink(cs); // tainted
-	sink(ss); // tainted
-}
-
-void test_string_constructors_assignments()
-{
-	{
-		std::string s1("hello");
-		std::string s2 = "hello";
-		std::string s3;
-		s3 = "hello";
-
-		sink(s1);
-		sink(s2);
-		sink(s3);
-	}
-
-	{
-		std::string s1(source());
-		std::string s2 = source();
-		std::string s3;
-		s3 = source();
-
-		sink(s1); // tainted
-		sink(s2); // tainted
-		sink(s3); // tainted
-	}
-
-	{
-		std::string s1;
-		std::string s2 = s1;
-		std::string s3;
-		s3 = s1;
-
-		sink(s1);
-		sink(s2);
-		sink(s3);
-	}
-
-	{
-		std::string s1 = std::string(source());
-		std::string s2;
-		s2 = std::string(source());
-
-		sink(s1); // tainted
-		sink(s2); // tainted
-	}
-}
-
-void sink(char) {}
-
-void test_range_based_for_loop_string() {
-	std::string s(source());
-	for(char c : s) {
-		sink(c); // tainted [NOT DETECTED by IR]
-	}
-
-	for(std::string::iterator it = s.begin(); it != s.end(); ++it) {
-		sink(*it); // tainted [NOT DETECTED]
-	}
-
-	for(char& c : s) {
-		sink(c); // tainted [NOT DETECTED by IR]
-	}
-
-	const std::string const_s(source());
-	for(const char& c : const_s) {
-		sink(c); // tainted [NOT DETECTED by IR]
-	}
-}
-
-
-
-
-
-
-
-
-namespace std {
-	template <class T>
-	class vector {
-	private:
-		void *data_;
-	public:
-		vector(int size);
-
-		T& operator[](int idx);
-		const T& operator[](int idx) const;
-
-		typedef std::iterator<random_access_iterator_tag, T> iterator;
-		typedef std::iterator<random_access_iterator_tag, const T> const_iterator;
-
-		iterator begin() noexcept;
-		iterator end() noexcept;
-
-		const_iterator begin() const noexcept;
-		const_iterator end() const noexcept;
-	};
-}
-
-void sink(int);
-
-void test_range_based_for_loop_vector(int source1) {
-	// Tainting the vector by allocating a tainted length. This doesn't represent
-	// how a vector would typically get tainted, but it allows this test to avoid
-	// being concerned with std::vector modeling.
-	std::vector<int> v(source1);
-
-	for(int x : v) {
-		sink(x); // tainted [NOT DETECTED by IR]
-	}
-
-	for(std::vector<int>::iterator it = v.begin(); it != v.end(); ++it) {
-		sink(*it); // tainted [NOT DETECTED]
-	}
-
-	for(int& x : v) {
-		sink(x); // tainted [NOT DETECTED by IR]
-	}
-
-	const std::vector<int> const_v(source1);
-	for(const int& x : const_v) {
-		sink(x); // tainted [NOT DETECTED by IR]
-	}
-}

cpp/ql/test/library-tests/dataflow/taint-tests/stl.h

@@ -0,0 +1,169 @@
+
+typedef unsigned long size_t;
+
+// --- string ---
+
+namespace std
+{
+	template<class charT> struct char_traits;
+
+	typedef size_t streamsize;
+
+	struct ptrdiff_t;
+
+	template <class iterator_category,
+			  class value_type,
+			  class difference_type = ptrdiff_t,
+			  class pointer_type = value_type*,
+			  class reference_type = value_type&>
+	struct iterator {
+		iterator &operator++();
+		iterator operator++(int);
+		bool operator==(iterator other) const;
+		bool operator!=(iterator other) const;
+		reference_type operator*() const;
+	};
+
+	struct input_iterator_tag {};
+	struct forward_iterator_tag : public input_iterator_tag {};
+	struct bidirectional_iterator_tag : public forward_iterator_tag {};
+	struct random_access_iterator_tag : public bidirectional_iterator_tag {};
+
+	template <class T> class allocator {
+	public:
+		allocator() throw();
+		typedef size_t size_type;
+	};
+	
+	template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
+	class basic_string {
+	public:
+		typedef typename Allocator::size_type size_type;
+		static const size_type npos = -1;
+
+		explicit basic_string(const Allocator& a = Allocator());
+		basic_string(const charT* s, const Allocator& a = Allocator());
+
+		const charT* c_str() const;
+		charT* data() noexcept;
+		size_t length() const;
+
+		typedef std::iterator<random_access_iterator_tag, charT> iterator;
+		typedef std::iterator<random_access_iterator_tag, const charT> const_iterator;
+
+		iterator begin();
+		iterator end();
+		const_iterator begin() const;
+		const_iterator end() const;
+		const_iterator cbegin() const;
+		const_iterator cend() const;
+
+		template<class T> basic_string& operator+=(const T& t);
+		basic_string& operator+=(const charT* s);
+		basic_string& append(const basic_string& str);
+		basic_string& append(const charT* s);
+		basic_string& append(size_type n, charT c);
+		basic_string& assign(const basic_string& str);
+		basic_string& assign(size_type n, charT c);
+		basic_string& insert(size_type pos, const basic_string& str);
+		basic_string& insert(size_type pos, size_type n, charT c);
+		basic_string& replace(size_type pos1, size_type n1, const basic_string& str);
+		basic_string& replace(size_type pos1, size_type n1, size_type n2, charT c);
+		size_type copy(charT* s, size_type n, size_type pos = 0) const;
+		void clear() noexcept;
+		basic_string substr(size_type pos = 0, size_type n = npos) const;
+		void swap(basic_string& s) noexcept/*(allocator_traits<Allocator>::propagate_on_container_swap::value || allocator_traits<Allocator>::is_always_equal::value)*/;
+	};
+
+	template<class charT, class traits, class Allocator> basic_string<charT, traits, Allocator> operator+(const basic_string<charT, traits, Allocator>& lhs, const basic_string<charT, traits, Allocator>& rhs);
+	template<class charT, class traits, class Allocator> basic_string<charT, traits, Allocator> operator+(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs);
+
+	typedef basic_string<char> string;
+
+	template <class charT, class traits = char_traits<charT> >
+	class basic_istream /*: virtual public basic_ios<charT,traits> - not needed for this test */ {
+	public:
+		basic_istream<charT,traits>& operator>>(int& n);
+	};
+
+	template <class charT, class traits = char_traits<charT> >
+	class basic_ostream /*: virtual public basic_ios<charT,traits> - not needed for this test */ {
+	public:
+		typedef charT char_type;
+		basic_ostream<charT,traits>& write(const char_type* s, streamsize n);
+
+		basic_ostream<charT, traits>& operator<<(int n);
+	};
+
+	template<class charT, class traits> basic_ostream<charT,traits>& operator<<(basic_ostream<charT,traits>&, const charT*);
+	template<class charT, class traits, class Allocator> basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>& os, const basic_string<charT, traits, Allocator>& str); 
+
+	template<class charT, class traits = char_traits<charT>>
+	class basic_iostream : public basic_istream<charT, traits>, public basic_ostream<charT, traits> {
+	public:
+	};
+
+	template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT>>
+	class basic_stringstream : public basic_iostream<charT, traits> {
+	public:
+		explicit basic_stringstream(/*ios_base::openmode which = ios_base::out|ios_base::in - not needed for this test*/);
+
+		basic_string<charT, traits, Allocator> str() const;
+	};
+
+	using stringstream = basic_stringstream<char>;
+}
+
+// --- vector ---
+
+namespace std {
+	template<class T, class Allocator = allocator<T>>
+	class vector { 
+	public:
+		using value_type = T;
+		using reference = value_type&;
+		using const_reference = const value_type&; 
+		using size_type = unsigned int;
+		using iterator = std::iterator<random_access_iterator_tag, T>;
+		using const_iterator = std::iterator<random_access_iterator_tag, const T>;
+
+		vector() noexcept(noexcept(Allocator())) : vector(Allocator()) { }
+		explicit vector(const Allocator&) noexcept;
+		explicit vector(size_type n, const Allocator& = Allocator());
+		vector(size_type n, const T& value, const Allocator& = Allocator()); 
+		~vector();
+
+		vector& operator=(const vector& x);
+		vector& operator=(vector&& x) noexcept/*(allocator_traits<Allocator>::propagate_on_container_move_assignment::value || allocator_traits<Allocator>::is_always_equal::value)*/;
+
+		iterator begin() noexcept;
+		const_iterator begin() const noexcept;
+		iterator end() noexcept;
+		const_iterator end() const noexcept;
+
+		size_type size() const noexcept;
+
+		reference operator[](size_type n);
+		const_reference operator[](size_type n) const;
+		const_reference at(size_type n) const;
+		reference at(size_type n);
+		reference front();
+		const_reference front() const;
+		reference back();
+		const_reference back() const;
+
+		T* data() noexcept;
+		const T* data() const noexcept;
+
+		void push_back(const T& x);
+		void push_back(T&& x);
+
+		iterator insert(const_iterator position, const T& x);
+		iterator insert(const_iterator position, T&& x);
+		iterator insert(const_iterator position, size_type n, const T& x);
+
+		void swap(vector&) noexcept/*(allocator_traits<Allocator>::propagate_on_container_swap::value || allocator_traits<Allocator>::is_always_equal::value)*/;
+
+		void clear() noexcept;
+	};
+}

cpp/ql/test/library-tests/dataflow/taint-tests/string.cpp

@@ -0,0 +1,323 @@
+
+#include "stl.h"
+
+using namespace std;
+
+char *source();
+
+namespace ns_char
+{
+	char source();
+}
+
+char *user_input() {
+  return source();
+}
+
+void sink(const char *s) {};
+void sink(const std::string &s) {};
+void sink(const char *filename, const char *mode);
+void sink(char) {}
+
+void test_string()
+{
+	char *a = source();
+	std::string b("123");
+	std::string c(source());
+
+	sink(a); // tainted
+	sink(b);
+	sink(c); // tainted
+	sink(b.c_str());
+	sink(c.c_str()); // tainted
+}
+
+void test_strings2()
+{
+	string path1 = user_input();
+	sink(path1.c_str(), "r"); // tainted
+
+	string path2;
+	path2 = user_input();
+	sink(path2.c_str(), "r"); // tainted
+
+	string path3(user_input());
+	sink(path3.c_str(), "r"); // tainted
+}
+
+void test_string3()
+{
+	const char *cs = source();
+
+	// convert char * -> std::string
+	std::string ss(cs);
+
+	sink(cs); // tainted
+	sink(ss); // tainted
+}
+
+void test_string4()
+{
+	const char *cs = source();
+
+	// convert char * -> std::string
+	std::string ss(cs);
+
+	// convert back std::string -> char *
+	cs = ss.c_str();
+
+	sink(cs); // tainted
+	sink(ss); // tainted
+}
+
+void test_string_constructors_assignments()
+{
+	{
+		std::string s1("hello");
+		std::string s2 = "hello";
+		std::string s3;
+		s3 = "hello";
+
+		sink(s1);
+		sink(s2);
+		sink(s3);
+	}
+
+	{
+		std::string s1(source());
+		std::string s2 = source();
+		std::string s3;
+		s3 = source();
+
+		sink(s1); // tainted
+		sink(s2); // tainted
+		sink(s3); // tainted
+	}
+
+	{
+		std::string s1;
+		std::string s2 = s1;
+		std::string s3;
+		s3 = s1;
+
+		sink(s1);
+		sink(s2);
+		sink(s3);
+	}
+
+	{
+		std::string s1 = std::string(source());
+		std::string s2;
+		s2 = std::string(source());
+
+		sink(s1); // tainted
+		sink(s2); // tainted
+	}
+}
+
+void test_range_based_for_loop_string() {
+	std::string s(source());
+	for(char c : s) {
+		sink(c); // tainted [NOT DETECTED by IR]
+	}
+
+	for(std::string::iterator it = s.begin(); it != s.end(); ++it) {
+		sink(*it); // tainted [NOT DETECTED]
+	}
+
+	for(char& c : s) {
+		sink(c); // tainted [NOT DETECTED by IR]
+	}
+
+	const std::string const_s(source());
+	for(const char& c : const_s) {
+		sink(c); // tainted [NOT DETECTED by IR]
+	}
+}
+
+void test_string_append() {
+	{
+		std::string s1("hello");
+		std::string s2(source());
+
+		sink(s1 + s1);
+		sink(s1 + s2); // tainted
+		sink(s2 + s1); // tainted
+		sink(s2 + s2); // tainted
+	
+		sink(s1 + " world");
+		sink(s1 + source()); // tainted
+	}
+
+	{
+		std::string s3("abc");
+		std::string s4(source());
+		std::string s5, s6, s7, s8, s9;
+
+		s5 = s3 + s4;
+		sink(s5); // tainted
+
+		s6 = s3;
+		s6 += s4;
+		sink(s6); // tainted
+
+		s7 = s3;
+		s7 += source();
+		s7 += " ";
+		sink(s7); // tainted
+
+		s8 = s3;
+		s8.append(s4);
+		sink(s8); // tainted
+
+		s9 = s3;
+		s9.append(source());
+		s9.append(" ");
+		sink(s9); // tainted
+	}
+
+	{
+		std::string s10("abc");
+		char c = ns_char::source();
+
+		s10.append(1, c);
+		sink(s10); // tainted
+	}
+}
+
+void test_string_assign() {
+	std::string s1("hello");
+	std::string s2(source());
+	char c = ns_char::source();
+	std::string s3, s4, s5;
+	std::string s6(source());
+
+	sink(s3.assign(s1));
+	sink(s3);
+
+	sink(s4.assign(s2)); // tainted
+	sink(s4); // tainted
+
+	sink(s5.assign(10, c)); // tainted
+	sink(s5); // tainted
+
+	sink(s6.assign(s1));
+	sink(s6); // [FALSE POSITIVE]
+}
+
+void test_string_insert() {
+	std::string s1("hello");
+	std::string s2(source());
+	char c = ns_char::source();
+	std::string s3, s4, s5, s6;
+
+	s3 = s1;
+	sink(s3.insert(0, s1));
+	sink(s3);
+
+	s4 = s2;
+	sink(s4.insert(0, s1)); // tainted
+	sink(s4); // tainted
+
+	s5 = s1;
+	sink(s5.insert(0, s2)); // tainted
+	sink(s5); // tainted
+
+	s6 = s1;
+	sink(s6.insert(0, 10, c)); // tainted
+	sink(s6); // tainted
+}
+
+void test_string_replace() {
+	std::string s1("hello");
+	std::string s2(source());
+	char c = ns_char::source();
+	std::string s3, s4, s5, s6;
+
+	s3 = s1;
+	sink(s3.replace(1, 2, s1));
+	sink(s3);
+
+	s4 = s2;
+	sink(s4.replace(1, 2, s1)); // tainted
+	sink(s4); // tainted
+
+	s5 = s1;
+	sink(s5.replace(1, 2, s2)); // tainted
+	sink(s5); // tainted
+
+	s6 = s1;
+	sink(s6.replace(1, 2, 10, c)); // tainted
+	sink(s6); // tainted
+}
+
+void test_string_copy() {
+	char b1[1024] = {0};
+	char b2[1024] = {0};
+	std::string s1("hello");
+	std::string s2(source());
+
+	s1.copy(b1, s1.length(), 0);
+	sink(b1);
+
+	s2.copy(b2, s1.length(), 0);
+	sink(b2); // tainted
+}
+
+void test_string_swap() {
+	std::string s1("hello");
+	std::string s2(source());
+	std::string s3("world");
+	std::string s4(source());
+
+	sink(s1);
+	sink(s2); // tainted
+	sink(s3);
+	sink(s4); // tainted
+
+	s1.swap(s2);
+	s4.swap(s3);
+
+	sink(s1); // tainted
+	sink(s2); // [FALSE POSITIVE]
+	sink(s3); // tainted
+	sink(s4); // [FALSE POSITIVE]
+}
+
+void test_string_clear() {
+	std::string s1(source());
+	std::string s2(source());
+	std::string s3(source());
+
+	sink(s1); // tainted
+	sink(s2); // tainted
+	sink(s3); // tainted
+
+	s1.clear();
+	s2 = "";
+	s3 = s3;
+
+	sink(s1); // [FALSE POSITIVE]
+	sink(s2);
+	sink(s3); // tainted
+}
+
+void test_string_data()
+{
+	std::string a("123");
+	std::string b(source());
+
+	sink(a.data());
+	sink(b.data()); // tainted
+	sink(a.length());
+	sink(b.length());
+}
+
+void test_string_substr()
+{
+	std::string a("123");
+	std::string b(source());
+
+	sink(a.substr(0, a.length()));
+	sink(b.substr(0, b.length())); // tainted
+}

cpp/ql/test/library-tests/dataflow/taint-tests/stringstream.cpp

@@ -0,0 +1,45 @@
+
+#include "stl.h"
+
+using namespace std;
+
+char *source();
+
+void sink(const std::string &s) {};
+void sink(const std::stringstream &s) {};
+
+void test_stringstream()
+{
+	std::stringstream ss1, ss2, ss3, ss4, ss5;
+	std::string t(source());
+
+	ss1 << "1234";
+	ss2 << source();
+	ss3 << "123" << source();
+	ss4 << source() << "456";
+	ss5 << t;
+
+	sink(ss1);
+	sink(ss2); // tainted [NOT DETECTED]
+	sink(ss3); // tainted [NOT DETECTED]
+	sink(ss4); // tainted [NOT DETECTED]
+	sink(ss5); // tainted [NOT DETECTED]
+	sink(ss1.str());
+	sink(ss2.str()); // tainted [NOT DETECTED]
+	sink(ss3.str()); // tainted [NOT DETECTED]
+	sink(ss4.str()); // tainted [NOT DETECTED]
+	sink(ss5.str()); // tainted [NOT DETECTED]
+}
+
+void test_stringstream_int(int source)
+{
+	std::stringstream ss1, ss2;
+
+	ss1 << 1234;
+	ss2 << source;
+
+	sink(ss1);
+	sink(ss2); // tainted [NOT DETECTED]
+	sink(ss1.str());
+	sink(ss2.str()); // tainted [NOT DETECTED]
+}

cpp/ql/test/library-tests/dataflow/taint-tests/taint.expected

@@ -32,27 +32,65 @@
 | movableclass.cpp:55:8:55:9 | s2 | movableclass.cpp:52:23:52:28 | call to source |
 | movableclass.cpp:64:8:64:9 | s2 | movableclass.cpp:23:55:23:60 | call to source |
 | movableclass.cpp:65:11:65:11 | call to operator= | movableclass.cpp:65:13:65:18 | call to source |
-| stl.cpp:101:7:101:7 | a | stl.cpp:97:12:97:17 | call to source |
-| stl.cpp:103:7:103:7 | c | stl.cpp:99:16:99:21 | call to source |
-| stl.cpp:105:9:105:13 | call to c_str | stl.cpp:99:16:99:21 | call to source |
-| stl.cpp:155:13:155:17 | call to c_str | stl.cpp:147:10:147:15 | call to source |
-| stl.cpp:159:13:159:17 | call to c_str | stl.cpp:147:10:147:15 | call to source |
-| stl.cpp:162:13:162:17 | call to c_str | stl.cpp:147:10:147:15 | call to source |
-| stl.cpp:172:7:172:8 | cs | stl.cpp:167:19:167:24 | call to source |
-| stl.cpp:173:7:173:8 | ss | stl.cpp:167:19:167:24 | call to source |
-| stl.cpp:186:7:186:8 | cs | stl.cpp:178:19:178:24 | call to source |
-| stl.cpp:187:7:187:8 | ss | stl.cpp:178:19:178:24 | call to source |
-| stl.cpp:209:8:209:9 | s1 | stl.cpp:204:18:204:23 | call to source |
-| stl.cpp:210:8:210:9 | s2 | stl.cpp:205:20:205:25 | call to source |
-| stl.cpp:211:8:211:9 | s3 | stl.cpp:207:8:207:13 | call to source |
-| stl.cpp:230:8:230:9 | s1 | stl.cpp:226:32:226:37 | call to source |
-| stl.cpp:231:8:231:9 | s2 | stl.cpp:228:20:228:25 | call to source |
-| stl.cpp:240:8:240:8 | c | stl.cpp:238:16:238:21 | call to source |
-| stl.cpp:248:8:248:8 | c | stl.cpp:238:16:238:21 | call to source |
-| stl.cpp:253:8:253:8 | c | stl.cpp:251:28:251:33 | call to source |
-| stl.cpp:295:8:295:8 | x | stl.cpp:288:43:288:49 | source1 |
-| stl.cpp:303:8:303:8 | x | stl.cpp:288:43:288:49 | source1 |
-| stl.cpp:308:8:308:8 | x | stl.cpp:288:43:288:49 | source1 |
+| string.cpp:28:7:28:7 | a | string.cpp:24:12:24:17 | call to source |
+| string.cpp:30:7:30:7 | c | string.cpp:26:16:26:21 | call to source |
+| string.cpp:32:9:32:13 | call to c_str | string.cpp:26:16:26:21 | call to source |
+| string.cpp:38:13:38:17 | call to c_str | string.cpp:14:10:14:15 | call to source |
+| string.cpp:42:13:42:17 | call to c_str | string.cpp:14:10:14:15 | call to source |
+| string.cpp:45:13:45:17 | call to c_str | string.cpp:14:10:14:15 | call to source |
+| string.cpp:55:7:55:8 | cs | string.cpp:50:19:50:24 | call to source |
+| string.cpp:56:7:56:8 | ss | string.cpp:50:19:50:24 | call to source |
+| string.cpp:69:7:69:8 | cs | string.cpp:61:19:61:24 | call to source |
+| string.cpp:70:7:70:8 | ss | string.cpp:61:19:61:24 | call to source |
+| string.cpp:92:8:92:9 | s1 | string.cpp:87:18:87:23 | call to source |
+| string.cpp:93:8:93:9 | s2 | string.cpp:88:20:88:25 | call to source |
+| string.cpp:94:8:94:9 | s3 | string.cpp:90:8:90:13 | call to source |
+| string.cpp:113:8:113:9 | s1 | string.cpp:109:32:109:37 | call to source |
+| string.cpp:114:8:114:9 | s2 | string.cpp:111:20:111:25 | call to source |
+| string.cpp:121:8:121:8 | c | string.cpp:119:16:119:21 | call to source |
+| string.cpp:129:8:129:8 | c | string.cpp:119:16:119:21 | call to source |
+| string.cpp:134:8:134:8 | c | string.cpp:132:28:132:33 | call to source |
+| string.cpp:144:11:144:11 | call to operator+ | string.cpp:141:18:141:23 | call to source |
+| string.cpp:145:11:145:11 | call to operator+ | string.cpp:141:18:141:23 | call to source |
+| string.cpp:146:11:146:11 | call to operator+ | string.cpp:141:18:141:23 | call to source |
+| string.cpp:149:11:149:11 | call to operator+ | string.cpp:149:13:149:18 | call to source |
+| string.cpp:158:8:158:9 | s5 | string.cpp:154:18:154:23 | call to source |
+| string.cpp:162:8:162:9 | s6 | string.cpp:154:18:154:23 | call to source |
+| string.cpp:167:8:167:9 | s7 | string.cpp:165:9:165:14 | call to source |
+| string.cpp:171:8:171:9 | s8 | string.cpp:154:18:154:23 | call to source |
+| string.cpp:176:8:176:9 | s9 | string.cpp:174:13:174:18 | call to source |
+| string.cpp:184:8:184:10 | s10 | string.cpp:181:12:181:26 | call to source |
+| string.cpp:198:10:198:15 | call to assign | string.cpp:190:17:190:22 | call to source |
+| string.cpp:199:7:199:8 | s4 | string.cpp:190:17:190:22 | call to source |
+| string.cpp:201:10:201:15 | call to assign | string.cpp:191:11:191:25 | call to source |
+| string.cpp:202:7:202:8 | s5 | string.cpp:191:11:191:25 | call to source |
+| string.cpp:205:7:205:8 | s6 | string.cpp:193:17:193:22 | call to source |
+| string.cpp:219:10:219:15 | call to insert | string.cpp:210:17:210:22 | call to source |
+| string.cpp:220:7:220:8 | s4 | string.cpp:210:17:210:22 | call to source |
+| string.cpp:223:10:223:15 | call to insert | string.cpp:210:17:210:22 | call to source |
+| string.cpp:224:7:224:8 | s5 | string.cpp:210:17:210:22 | call to source |
+| string.cpp:227:10:227:15 | call to insert | string.cpp:211:11:211:25 | call to source |
+| string.cpp:228:7:228:8 | s6 | string.cpp:211:11:211:25 | call to source |
+| string.cpp:242:10:242:16 | call to replace | string.cpp:233:17:233:22 | call to source |
+| string.cpp:243:7:243:8 | s4 | string.cpp:233:17:233:22 | call to source |
+| string.cpp:246:10:246:16 | call to replace | string.cpp:233:17:233:22 | call to source |
+| string.cpp:247:7:247:8 | s5 | string.cpp:233:17:233:22 | call to source |
+| string.cpp:250:10:250:16 | call to replace | string.cpp:234:11:234:25 | call to source |
+| string.cpp:251:7:251:8 | s6 | string.cpp:234:11:234:25 | call to source |
+| string.cpp:264:7:264:8 | b2 | string.cpp:258:17:258:22 | call to source |
+| string.cpp:274:7:274:8 | s2 | string.cpp:269:17:269:22 | call to source |
+| string.cpp:276:7:276:8 | s4 | string.cpp:271:17:271:22 | call to source |
+| string.cpp:281:7:281:8 | s1 | string.cpp:269:17:269:22 | call to source |
+| string.cpp:282:7:282:8 | s2 | string.cpp:269:17:269:22 | call to source |
+| string.cpp:283:7:283:8 | s3 | string.cpp:271:17:271:22 | call to source |
+| string.cpp:284:7:284:8 | s4 | string.cpp:271:17:271:22 | call to source |
+| string.cpp:292:7:292:8 | s1 | string.cpp:288:17:288:22 | call to source |
+| string.cpp:293:7:293:8 | s2 | string.cpp:289:17:289:22 | call to source |
+| string.cpp:294:7:294:8 | s3 | string.cpp:290:17:290:22 | call to source |
+| string.cpp:300:7:300:8 | s1 | string.cpp:288:17:288:22 | call to source |
+| string.cpp:302:7:302:8 | s3 | string.cpp:290:17:290:22 | call to source |
+| string.cpp:311:9:311:12 | call to data | string.cpp:308:16:308:21 | call to source |
+| string.cpp:322:9:322:14 | call to substr | string.cpp:319:16:319:21 | call to source |
 | structlikeclass.cpp:35:8:35:9 | s1 | structlikeclass.cpp:29:22:29:27 | call to source |
 | structlikeclass.cpp:36:8:36:9 | s2 | structlikeclass.cpp:30:24:30:29 | call to source |
 | structlikeclass.cpp:37:8:37:9 | s3 | structlikeclass.cpp:29:22:29:27 | call to source |
@@ -159,3 +197,21 @@
 | taint.cpp:470:7:470:7 | x | taint.cpp:462:6:462:11 | call to source |
 | taint.cpp:471:7:471:7 | y | taint.cpp:462:6:462:11 | call to source |
 | taint.cpp:485:7:485:10 | line | taint.cpp:480:26:480:32 | source1 |
+| vector.cpp:20:8:20:8 | x | vector.cpp:16:43:16:49 | source1 |
+| vector.cpp:28:8:28:8 | x | vector.cpp:16:43:16:49 | source1 |
+| vector.cpp:33:8:33:8 | x | vector.cpp:16:43:16:49 | source1 |
+| vector.cpp:70:7:70:8 | v5 | vector.cpp:69:15:69:20 | call to source |
+| vector.cpp:71:10:71:14 | call to front | vector.cpp:69:15:69:20 | call to source |
+| vector.cpp:72:10:72:13 | call to back | vector.cpp:69:15:69:20 | call to source |
+| vector.cpp:109:7:109:8 | v1 | vector.cpp:106:15:106:20 | call to source |
+| vector.cpp:112:7:112:8 | v4 | vector.cpp:107:15:107:20 | call to source |
+| vector.cpp:117:7:117:8 | v1 | vector.cpp:106:15:106:20 | call to source |
+| vector.cpp:118:7:118:8 | v2 | vector.cpp:106:15:106:20 | call to source |
+| vector.cpp:119:7:119:8 | v3 | vector.cpp:107:15:107:20 | call to source |
+| vector.cpp:120:7:120:8 | v4 | vector.cpp:107:15:107:20 | call to source |
+| vector.cpp:130:7:130:8 | v1 | vector.cpp:126:15:126:20 | call to source |
+| vector.cpp:131:7:131:8 | v2 | vector.cpp:127:15:127:20 | call to source |
+| vector.cpp:132:7:132:8 | v3 | vector.cpp:128:15:128:20 | call to source |
+| vector.cpp:139:7:139:8 | v1 | vector.cpp:126:15:126:20 | call to source |
+| vector.cpp:140:7:140:8 | v2 | vector.cpp:127:15:127:20 | call to source |
+| vector.cpp:141:7:141:8 | v3 | vector.cpp:128:15:128:20 | call to source |

cpp/ql/test/library-tests/dataflow/taint-tests/test_diff.expected

@@ -30,26 +30,64 @@
 | movableclass.cpp:55:8:55:9 | movableclass.cpp:52:23:52:28 | AST only |
 | movableclass.cpp:64:8:64:9 | movableclass.cpp:23:55:23:60 | AST only |
 | movableclass.cpp:65:11:65:11 | movableclass.cpp:65:13:65:18 | AST only |
-| stl.cpp:103:7:103:7 | stl.cpp:99:16:99:21 | AST only |
-| stl.cpp:105:9:105:13 | stl.cpp:99:16:99:21 | AST only |
-| stl.cpp:155:13:155:17 | stl.cpp:147:10:147:15 | AST only |
-| stl.cpp:159:13:159:17 | stl.cpp:147:10:147:15 | AST only |
-| stl.cpp:162:13:162:17 | stl.cpp:147:10:147:15 | AST only |
-| stl.cpp:172:7:172:8 | stl.cpp:167:19:167:26 | IR only |
-| stl.cpp:173:7:173:8 | stl.cpp:167:19:167:24 | AST only |
-| stl.cpp:186:7:186:8 | stl.cpp:178:19:178:24 | AST only |
-| stl.cpp:187:7:187:8 | stl.cpp:178:19:178:24 | AST only |
-| stl.cpp:209:8:209:9 | stl.cpp:204:18:204:23 | AST only |
-| stl.cpp:210:8:210:9 | stl.cpp:205:20:205:25 | AST only |
-| stl.cpp:211:8:211:9 | stl.cpp:207:8:207:13 | AST only |
-| stl.cpp:230:8:230:9 | stl.cpp:226:32:226:37 | AST only |
-| stl.cpp:231:8:231:9 | stl.cpp:228:20:228:25 | AST only |
-| stl.cpp:240:8:240:8 | stl.cpp:238:16:238:21 | AST only |
-| stl.cpp:248:8:248:8 | stl.cpp:238:16:238:21 | AST only |
-| stl.cpp:253:8:253:8 | stl.cpp:251:28:251:33 | AST only |
-| stl.cpp:295:8:295:8 | stl.cpp:288:43:288:49 | AST only |
-| stl.cpp:303:8:303:8 | stl.cpp:288:43:288:49 | AST only |
-| stl.cpp:308:8:308:8 | stl.cpp:288:43:288:49 | AST only |
+| string.cpp:30:7:30:7 | string.cpp:26:16:26:21 | AST only |
+| string.cpp:32:9:32:13 | string.cpp:26:16:26:21 | AST only |
+| string.cpp:38:13:38:17 | string.cpp:14:10:14:15 | AST only |
+| string.cpp:42:13:42:17 | string.cpp:14:10:14:15 | AST only |
+| string.cpp:45:13:45:17 | string.cpp:14:10:14:15 | AST only |
+| string.cpp:55:7:55:8 | string.cpp:50:19:50:26 | IR only |
+| string.cpp:56:7:56:8 | string.cpp:50:19:50:24 | AST only |
+| string.cpp:69:7:69:8 | string.cpp:61:19:61:24 | AST only |
+| string.cpp:70:7:70:8 | string.cpp:61:19:61:24 | AST only |
+| string.cpp:92:8:92:9 | string.cpp:87:18:87:23 | AST only |
+| string.cpp:93:8:93:9 | string.cpp:88:20:88:25 | AST only |
+| string.cpp:94:8:94:9 | string.cpp:90:8:90:13 | AST only |
+| string.cpp:113:8:113:9 | string.cpp:109:32:109:37 | AST only |
+| string.cpp:114:8:114:9 | string.cpp:111:20:111:25 | AST only |
+| string.cpp:121:8:121:8 | string.cpp:119:16:119:21 | AST only |
+| string.cpp:129:8:129:8 | string.cpp:119:16:119:21 | AST only |
+| string.cpp:134:8:134:8 | string.cpp:132:28:132:33 | AST only |
+| string.cpp:144:11:144:11 | string.cpp:141:18:141:23 | AST only |
+| string.cpp:145:11:145:11 | string.cpp:141:18:141:23 | AST only |
+| string.cpp:146:11:146:11 | string.cpp:141:18:141:23 | AST only |
+| string.cpp:149:11:149:11 | string.cpp:149:13:149:18 | AST only |
+| string.cpp:158:8:158:9 | string.cpp:154:18:154:23 | AST only |
+| string.cpp:162:8:162:9 | string.cpp:154:18:154:23 | AST only |
+| string.cpp:167:8:167:9 | string.cpp:165:9:165:14 | AST only |
+| string.cpp:171:8:171:9 | string.cpp:154:18:154:23 | AST only |
+| string.cpp:176:8:176:9 | string.cpp:174:13:174:18 | AST only |
+| string.cpp:184:8:184:10 | string.cpp:181:12:181:26 | AST only |
+| string.cpp:198:10:198:15 | string.cpp:190:17:190:22 | AST only |
+| string.cpp:199:7:199:8 | string.cpp:190:17:190:22 | AST only |
+| string.cpp:201:10:201:15 | string.cpp:191:11:191:25 | AST only |
+| string.cpp:202:7:202:8 | string.cpp:191:11:191:25 | AST only |
+| string.cpp:205:7:205:8 | string.cpp:193:17:193:22 | AST only |
+| string.cpp:219:10:219:15 | string.cpp:210:17:210:22 | AST only |
+| string.cpp:220:7:220:8 | string.cpp:210:17:210:22 | AST only |
+| string.cpp:223:10:223:15 | string.cpp:210:17:210:22 | AST only |
+| string.cpp:224:7:224:8 | string.cpp:210:17:210:22 | AST only |
+| string.cpp:227:10:227:15 | string.cpp:211:11:211:25 | AST only |
+| string.cpp:228:7:228:8 | string.cpp:211:11:211:25 | AST only |
+| string.cpp:242:10:242:16 | string.cpp:233:17:233:22 | AST only |
+| string.cpp:243:7:243:8 | string.cpp:233:17:233:22 | AST only |
+| string.cpp:246:10:246:16 | string.cpp:233:17:233:22 | AST only |
+| string.cpp:247:7:247:8 | string.cpp:233:17:233:22 | AST only |
+| string.cpp:250:10:250:16 | string.cpp:234:11:234:25 | AST only |
+| string.cpp:251:7:251:8 | string.cpp:234:11:234:25 | AST only |
+| string.cpp:264:7:264:8 | string.cpp:258:17:258:22 | AST only |
+| string.cpp:274:7:274:8 | string.cpp:269:17:269:22 | AST only |
+| string.cpp:276:7:276:8 | string.cpp:271:17:271:22 | AST only |
+| string.cpp:281:7:281:8 | string.cpp:269:17:269:22 | AST only |
+| string.cpp:282:7:282:8 | string.cpp:269:17:269:22 | AST only |
+| string.cpp:283:7:283:8 | string.cpp:271:17:271:22 | AST only |
+| string.cpp:284:7:284:8 | string.cpp:271:17:271:22 | AST only |
+| string.cpp:292:7:292:8 | string.cpp:288:17:288:22 | AST only |
+| string.cpp:293:7:293:8 | string.cpp:289:17:289:22 | AST only |
+| string.cpp:294:7:294:8 | string.cpp:290:17:290:22 | AST only |
+| string.cpp:300:7:300:8 | string.cpp:288:17:288:22 | AST only |
+| string.cpp:302:7:302:8 | string.cpp:290:17:290:22 | AST only |
+| string.cpp:311:9:311:12 | string.cpp:308:16:308:21 | AST only |
+| string.cpp:322:9:322:14 | string.cpp:319:16:319:21 | AST only |
 | structlikeclass.cpp:35:8:35:9 | structlikeclass.cpp:29:22:29:27 | AST only |
 | structlikeclass.cpp:36:8:36:9 | structlikeclass.cpp:30:24:30:29 | AST only |
 | structlikeclass.cpp:37:8:37:9 | structlikeclass.cpp:29:22:29:27 | AST only |
@@ -94,3 +132,21 @@
 | taint.cpp:446:7:446:7 | taint.cpp:445:14:445:28 | AST only |
 | taint.cpp:447:9:447:17 | taint.cpp:445:14:445:28 | AST only |
 | taint.cpp:471:7:471:7 | taint.cpp:462:6:462:11 | AST only |
+| vector.cpp:20:8:20:8 | vector.cpp:16:43:16:49 | AST only |
+| vector.cpp:28:8:28:8 | vector.cpp:16:43:16:49 | AST only |
+| vector.cpp:33:8:33:8 | vector.cpp:16:43:16:49 | AST only |
+| vector.cpp:70:7:70:8 | vector.cpp:69:15:69:20 | AST only |
+| vector.cpp:71:10:71:14 | vector.cpp:69:15:69:20 | AST only |
+| vector.cpp:72:10:72:13 | vector.cpp:69:15:69:20 | AST only |
+| vector.cpp:109:7:109:8 | vector.cpp:106:15:106:20 | AST only |
+| vector.cpp:112:7:112:8 | vector.cpp:107:15:107:20 | AST only |
+| vector.cpp:117:7:117:8 | vector.cpp:106:15:106:20 | AST only |
+| vector.cpp:118:7:118:8 | vector.cpp:106:15:106:20 | AST only |
+| vector.cpp:119:7:119:8 | vector.cpp:107:15:107:20 | AST only |
+| vector.cpp:120:7:120:8 | vector.cpp:107:15:107:20 | AST only |
+| vector.cpp:130:7:130:8 | vector.cpp:126:15:126:20 | AST only |
+| vector.cpp:131:7:131:8 | vector.cpp:127:15:127:20 | AST only |
+| vector.cpp:132:7:132:8 | vector.cpp:128:15:128:20 | AST only |
+| vector.cpp:139:7:139:8 | vector.cpp:126:15:126:20 | AST only |
+| vector.cpp:140:7:140:8 | vector.cpp:127:15:127:20 | AST only |
+| vector.cpp:141:7:141:8 | vector.cpp:128:15:128:20 | AST only |

cpp/ql/test/library-tests/dataflow/taint-tests/test_ir.expected

@@ -1,10 +1,10 @@
 | format.cpp:157:7:157:22 | (int)... | format.cpp:147:12:147:25 | call to source |
 | format.cpp:157:7:157:22 | access to array | format.cpp:147:12:147:25 | call to source |
 | format.cpp:158:7:158:27 | ... + ... | format.cpp:148:16:148:30 | call to source |
-| stl.cpp:101:7:101:7 | (const char *)... | stl.cpp:97:12:97:17 | call to source |
-| stl.cpp:101:7:101:7 | a | stl.cpp:97:12:97:17 | call to source |
-| stl.cpp:172:7:172:8 | cs | stl.cpp:167:19:167:24 | call to source |
-| stl.cpp:172:7:172:8 | cs | stl.cpp:167:19:167:26 | (const char *)... |
+| string.cpp:28:7:28:7 | (const char *)... | string.cpp:24:12:24:17 | call to source |
+| string.cpp:28:7:28:7 | a | string.cpp:24:12:24:17 | call to source |
+| string.cpp:55:7:55:8 | cs | string.cpp:50:19:50:24 | call to source |
+| string.cpp:55:7:55:8 | cs | string.cpp:50:19:50:26 | (const char *)... |
 | structlikeclass.cpp:38:8:38:9 | s4 | structlikeclass.cpp:33:8:33:13 | call to source |
 | structlikeclass.cpp:61:8:61:9 | s2 | structlikeclass.cpp:58:24:58:29 | call to source |
 | structlikeclass.cpp:62:8:62:20 | ... = ... | structlikeclass.cpp:62:13:62:18 | call to source |

cpp/ql/test/library-tests/dataflow/taint-tests/vector.cpp

@@ -0,0 +1,143 @@
+
+#include "stl.h"
+
+using namespace std;
+
+int source();
+
+namespace ns_char
+{
+	char source();
+}
+
+void sink(int);
+void sink(std::vector<int> &);
+
+void test_range_based_for_loop_vector(int source1) {
+	std::vector<int> v(100, source1);
+
+	for(int x : v) {
+		sink(x); // tainted [NOT DETECTED by IR]
+	}
+
+	for(std::vector<int>::iterator it = v.begin(); it != v.end(); ++it) {
+		sink(*it); // tainted [NOT DETECTED]
+	}
+
+	for(int& x : v) {
+		sink(x); // tainted [NOT DETECTED by IR]
+	}
+
+	const std::vector<int> const_v(100, source1);
+	for(const int& x : const_v) {
+		sink(x); // tainted [NOT DETECTED by IR]
+	}
+}
+
+void test_element_taint(int x) {
+	std::vector<int> v1(10), v2(10), v3(10), v4(10), v5(10), v6(10), v7(10), v8(10), v9(10);
+
+	v1[0] = 0;
+	v1[1] = 0;
+	v1[x] = 0;
+	v1.push_back(1);
+	sink(v1);
+	sink(v1[0]);
+	sink(v1[1]);
+	sink(v1[x]);
+	sink(v1.front());
+	sink(v1.back());
+
+	v2[0] = source();
+	sink(v2); // tainted [NOT DETECTED]
+	sink(v2[0]); // tainted [NOT DETECTED]
+	sink(v2[1]);
+	sink(v2[x]); // potentially tainted
+
+	v3 = v2;
+	sink(v3); // tainted [NOT DETECTED]
+	sink(v3[0]); // tainted [NOT DETECTED]
+	sink(v3[1]);
+	sink(v3[x]); // potentially tainted
+
+	v4[x] = source();
+	sink(v4); // tainted [NOT DETECTED]
+	sink(v4[0]); // potentially tainted
+	sink(v4[1]); // potentially tainted
+	sink(v4[x]); // tainted [NOT DETECTED]
+
+	v5.push_back(source());
+	sink(v5); // tainted
+	sink(v5.front()); // [FALSE POSITIVE]
+	sink(v5.back()); // tainted
+
+	v6.data()[2] = source();
+	sink(v6); // tainted [NOT DETECTED]
+	sink(v6.data()[2]); // tainted [NOT DETECTED]
+
+	{
+		const std::vector<int> &v7c = v7; // (workaround because our iterators don't convert to const_iterator)
+		std::vector<int>::const_iterator it = v7c.begin();
+		v7.insert(it, source());
+	}
+	sink(v7); // tainted [NOT DETECTED]
+	sink(v7.front()); // tainted [NOT DETECTED]
+	sink(v7.back());
+
+	{
+		const std::vector<int> &v8c = v8;
+		std::vector<int>::const_iterator it = v8c.begin();
+		v8.insert(it, 10, ns_char::source());
+	}
+	sink(v8); // tainted [NOT DETECTED]
+	sink(v8.front()); // tainted [NOT DETECTED]
+	sink(v8.back());
+
+	v9.at(x) = source();
+	sink(v9); // tainted [NOT DETECTED]
+	sink(v9.at(0)); // potentially tainted
+	sink(v9.at(1)); // potentially tainted
+	sink(v9.at(x)); // tainted [NOT DETECTED]
+}
+
+void test_vector_swap() {
+	std::vector<int> v1(10), v2(10), v3(10), v4(10);
+
+	v1.push_back(source());
+	v4.push_back(source());
+
+	sink(v1); // tainted
+	sink(v2);
+	sink(v3);
+	sink(v4); // tainted
+
+	v1.swap(v2);
+	v3.swap(v4);
+
+	sink(v1); // [FALSE POSITIVE]
+	sink(v2); // tainted
+	sink(v3); // tainted
+	sink(v4); // [FALSE POSITIVE]
+}
+
+void test_vector_clear() {
+	std::vector<int> v1(10), v2(10), v3(10), v4(10);
+
+	v1.push_back(source());
+	v2.push_back(source());
+	v3.push_back(source());
+
+	sink(v1); // tainted
+	sink(v2); // tainted
+	sink(v3); // tainted
+	sink(v4);
+
+	v1.clear();
+	v2 = v2;
+	v3 = v4;
+
+	sink(v1); // [FALSE POSITIVE]
+	sink(v2); // tainted
+	sink(v3); // [FALSE POSITIVE]
+	sink(v4);
+}

cpp/ql/test/library-tests/ir/ssa/ssa.cpp

@@ -291,7 +291,7 @@ struct A {
 Point *NewAliasing(int x) {
   Point* p = new Point;
   Point* q = new Point;
-  int j = new A(new A(x))->i;
+  int j = (new A(new A(x)))->i;
   A* a = new A;
   return p;
 }
@@ -310,4 +310,4 @@ class ThisAliasTest {
   void setX(int arg) {
     this->x = arg;
   }
-};
+};

cpp/ql/test/library-tests/rangeanalysis/SimpleRangeAnalysis/lowerBound.ql

@@ -1,4 +1,4 @@
 import semmle.code.cpp.rangeanalysis.SimpleRangeAnalysis
 
 from VariableAccess expr
-select expr, lowerBound(expr)
+select expr, lowerBound(expr).toString()

cpp/ql/test/library-tests/rangeanalysis/SimpleRangeAnalysis/test.c

@@ -422,7 +422,7 @@ void test17() {
   out(i); // 50
 
   i = 20 + (j -= 10);
-  out(i); // 60 [BUG: the analysis thinks it's 2^-31 .. 2^31-1]
+  out(i); // 60
 }
 
 // Tests for unsigned multiplication.
@@ -463,3 +463,73 @@ int test_unsigned_mult02(unsigned b) {
 
   return total;
 }
+
+unsigned long mult_rounding() {
+  unsigned long x, y, xy;
+  x = y = 1000000003UL; // 1e9 + 3
+  xy = x * y;
+  return xy; // BUG: upper bound should be >= 1000000006000000009UL
+}
+
+unsigned long mult_overflow() {
+  unsigned long x, y, xy;
+  x = 274177UL;
+  y = 67280421310721UL;
+  xy = x * y;
+  return xy; // BUG: upper bound should be >= 18446744073709551617UL
+}
+
+unsigned long mult_lower_bound(unsigned int ui, unsigned long ul) {
+  if (ui >= 10) {
+    unsigned long result = (unsigned long)ui * ui;
+    return result; // BUG: upper bound should be >= 18446744065119617025
+  }
+  if (ul >= 10) {
+    unsigned long result = ul * ul;
+    return result; // lower bound is correctly 0 (overflow is possible)
+  }
+  return 0;
+}
+
+unsigned long mul_assign(unsigned int ui) {
+  if (ui <= 10 && ui >= 2) {
+    ui *= ui + 0;
+    return ui; // 4 .. 100
+  }
+
+  unsigned int uiconst = 10;
+  uiconst *= 4;
+
+  unsigned long ulconst = 10;
+  ulconst *= 4;
+  return uiconst + ulconst; // 40 .. 40 for both
+}
+
+int mul_by_constant(int i, int j) {
+  if (i >= -1 && i <= 2) {
+    i = 5 * i;
+    out(i); // -5 .. 10
+
+    i = i * -3;
+    out(i); // -30 .. 15
+
+    i *= 7;
+    out(i); // -210 .. 105
+
+    i *= -11;
+    out(i); // -1155 .. 2310
+  }
+  if (i == -1) {
+    i = i * (int)0xffFFffFF; // fully converted literal is -1
+    out(i); // 1 .. 1
+  }
+  i = i * -1;
+  out(   i); // -2^31 .. 2^31-1
+
+  signed char sc = 1;
+  i = (*&sc *= 2);
+  out(sc); // demonstrate that we couldn't analyze the LHS of the `*=` above...
+  out(i); // -128 .. 127 // ... but we can still bound its result by its type.
+
+  return 0;
+}

cpp/ql/test/library-tests/rangeanalysis/SimpleRangeAnalysis/upperBound.ql

@@ -1,4 +1,4 @@
 import semmle.code.cpp.rangeanalysis.SimpleRangeAnalysis
 
 from VariableAccess expr
-select expr, upperBound(expr)
+select expr, upperBound(expr).toString()

cpp/ql/test/query-tests/Likely Bugs/Arithmetic/PointlessComparison/PointlessComparison.c

@@ -385,10 +385,39 @@ void bitwise_ands()
 
 void unsigned_mult(unsigned int x, unsigned int y) {
   if(x < 13 && y < 35) {
-      if(x * y > 1024) {} // always false [NOT DETECTED]
+      if(x * y > 1024) {} // always false
       if(x * y < 204) {}
       if(x >= 3 && y >= 2) {
-        if(x * y < 5) {} // always false [NOT DETECTED]
+        if(x * y < 5) {} // always false
       }
   }
-}
+}
+
+void mult_rounding() {
+  unsigned long x, y, xy;
+  x = y = 1000000003UL; // 1e9 + 3
+  xy = 1000000006000000009UL; // x * y, precisely
+  // Even though the range analysis wrongly considers x*y to be xy - 9, there
+  // are no PointlessComparison false positives in these tests because alerts
+  // are suppressed when ulp() < 1, which roughly means that the number is
+  // larger than 2^53.
+  if (x * y < xy) {} // always false [NOT DETECTED]
+  if (x * y > xy) {} // always false [NOT DETECTED]
+}
+
+void mult_overflow() {
+  unsigned long x, y;
+  // The following two numbers multiply to 2^64 + 1, which is 1 when truncated
+  // to 64-bit unsigned.
+  x = 274177UL;
+  y = 67280421310721UL;
+  if (x * y == 1) {} // always true [BUG: reported as always false]
+
+  // This bug appears to be caused by
+  // `RangeAnalysisUtils::typeUpperBound(unsigned long)` having a result of
+  // 2**64 + 384, making the range analysis think that the multiplication can't
+  // overflow. The correct `typeUpperBound` would be 2**64 - 1, but we can't
+  // represent that with a QL float or int. We could make `typeUpperBound`
+  // exclusive instead of inclusive, but there is no exclusive upper bound for
+  // floats.
+}

cpp/ql/test/query-tests/Likely Bugs/Arithmetic/PointlessComparison/PointlessComparison.expected

@@ -41,7 +41,10 @@
 | PointlessComparison.c:372:6:372:16 | ... >= ... | Comparison is always true because ... >> ... >= 1. |
 | PointlessComparison.c:373:6:373:16 | ... >= ... | Comparison is always false because ... >> ... <= 1. |
 | PointlessComparison.c:383:6:383:17 | ... >= ... | Comparison is always false because ... & ... <= 2. |
-| PointlessComparison.cpp:36:6:36:33 | ... >= ... | Comparison is always false because ... >> ... <= 9223372036854776000. |
+| PointlessComparison.c:388:10:388:21 | ... > ... | Comparison is always false because ... * ... <= 408. |
+| PointlessComparison.c:391:12:391:20 | ... < ... | Comparison is always false because ... * ... >= 6. |
+| PointlessComparison.c:414:7:414:16 | ... == ... | Comparison is always false because ... * ... >= 18446744073709551616. |
+| PointlessComparison.cpp:36:6:36:33 | ... >= ... | Comparison is always false because ... >> ... <= 9223372036854775808. |
 | PointlessComparison.cpp:41:6:41:29 | ... >= ... | Comparison is always false because ... >> ... <= 140737488355327.5. |
 | PointlessComparison.cpp:42:6:42:29 | ... >= ... | Comparison is always false because ... >> ... <= 140737488355327.5. |
 | PointlessComparison.cpp:43:6:43:29 | ... >= ... | Comparison is always true because ... >> ... >= 140737488355327.5. |

cpp/ql/test/query-tests/Security/CWE/CWE-190/semmle/tainted/IntegerOverflowTainted.expected

@@ -2,5 +2,8 @@
 | test3.c:13:16:13:19 | * ... | $@ flows to here and is used in an expression which might overflow negatively. | test3.c:11:15:11:18 | argv | User-provided value |
 | test4.cpp:13:17:13:20 | access to array | $@ flows to here and is used in an expression which might overflow negatively. | test4.cpp:9:13:9:16 | argv | User-provided value |
 | test5.cpp:10:9:10:15 | call to strtoul | $@ flows to here and is used in an expression which might overflow. | test5.cpp:9:7:9:9 | buf | User-provided value |
+| test5.cpp:17:6:17:27 | ... * ... | $@ flows to here and is used in an expression which might overflow. | test5.cpp:9:7:9:9 | buf | User-provided value |
+| test5.cpp:19:6:19:13 | ... * ... | $@ flows to here and is used in an expression which might overflow. | test5.cpp:9:7:9:9 | buf | User-provided value |
+| test.c:14:15:14:35 | ... * ... | $@ flows to here and is used in an expression which might overflow. | test.c:11:29:11:32 | argv | User-provided value |
 | test.c:44:7:44:12 | ... -- | $@ flows to here and is used in an expression which might overflow negatively. | test.c:41:17:41:20 | argv | User-provided value |
 | test.c:54:7:54:12 | ... -- | $@ flows to here and is used in an expression which might overflow negatively. | test.c:51:17:51:20 | argv | User-provided value |