Merge pull request #16099 from github/release-prep/2.17.0

Release preparation for version 2.17.0

.bazelversion

@@ -1 +1 @@
-7.0.2
+7.1.0

.github/workflows/cpp-swift-analysis.yml

@@ -0,0 +1,55 @@
+name: "Code scanning - C++"
+
+on:
+  push:
+    branches:
+      - main
+      - 'rc/*'
+  pull_request:
+    branches:
+      - main
+      - 'rc/*'
+    paths:
+      - 'swift/**'
+      - '.github/codeql/**'
+      - '.github/workflows/cpp-swift-analysis.yml'
+  schedule:
+    - cron: '0 9 * * 1'
+
+jobs:
+  CodeQL-Build:
+
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+      security-events: write
+      pull-requests: read
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v4
+
+    # Initializes the CodeQL tools for scanning.
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@main
+      # Override language selection by uncommenting this and choosing your languages
+      with:
+        languages: cpp
+        config-file: ./.github/codeql/codeql-config.yml
+  
+    - name: "[Ubuntu] Remove GCC 13 from runner image"
+      shell: bash
+      run: |
+        sudo rm -f /etc/apt/sources.list.d/ubuntu-toolchain-r-ubuntu-test-jammy.list
+        sudo apt-get update
+        sudo apt-get install -y --allow-downgrades libc6=2.35-* libc6-dev=2.35-* libstdc++6=12.3.0-* libgcc-s1=12.3.0-*
+
+    - name: "Build Swift extractor using Bazel"
+      run: |
+        bazel clean --expunge
+        bazel run //swift:create-extractor-pack --nouse_action_cache --noremote_accept_cached --noremote_upload_local_results --spawn_strategy=local --features=-layering_check
+        bazel shutdown
+
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@main

CODEOWNERS

@@ -1,4 +1,5 @@
 /cpp/ @github/codeql-c-analysis
+/cpp/autobuilder/ @github/codeql-c-extractor
 /csharp/ @github/codeql-csharp
 /go/ @github/codeql-go
 /java/ @github/codeql-java

codeql-workspace.yml

@@ -6,6 +6,7 @@ provide:
   - "*/ql/consistency-queries/qlpack.yml"
   - "*/ql/automodel/src/qlpack.yml"
   - "*/ql/automodel/test/qlpack.yml"
+  - "python/extractor/qlpack.yml"
   - "shared/**/qlpack.yml"
   - "cpp/ql/test/query-tests/Security/CWE/CWE-190/semmle/tainted/qlpack.yml"
   - "go/ql/config/legacy-support/qlpack.yml"
@@ -27,7 +28,6 @@ provide:
   - "misc/suite-helpers/qlpack.yml"
   - "ruby/extractor-pack/codeql-extractor.yml"
   - "swift/extractor-pack/codeql-extractor.yml"
-  - "swift/integration-tests/qlpack.yml"
   - "ql/extractor-pack/codeql-extractor.yml"
   - ".github/codeql/extensions/**/codeql-pack.yml"
 

config/identical-files.json

@@ -255,7 +255,6 @@
     "cpp/ql/lib/semmle/code/cpp/XML.qll",
     "csharp/ql/lib/semmle/code/csharp/XML.qll",
     "java/ql/lib/semmle/code/xml/XML.qll",
-    "javascript/ql/lib/semmle/javascript/XML.qll",
     "python/ql/lib/semmle/python/xml/XML.qll"
   ],
   "DuplicationProblems.inc.qhelp": [
@@ -372,4 +371,4 @@
     "python/ql/test/experimental/dataflow/model-summaries/InlineTaintTest.ext.yml",
     "python/ql/test/experimental/dataflow/model-summaries/NormalDataflowTest.ext.yml"
   ]
-}
+}

cpp/downgrades/aa7ff0ab32cd4674f6ab731d32fea64116997b05/exprs.ql

@@ -0,0 +1,13 @@
+class Expr extends @expr {
+  string toString() { none() }
+}
+
+class Location extends @location_expr {
+  string toString() { none() }
+}
+
+from Expr expr, int kind, int kind_new, Location loc
+where
+  exprs(expr, kind, loc) and
+  if kind = 363 then kind_new = 1 else kind_new = kind
+select expr, kind_new, loc

cpp/downgrades/aa7ff0ab32cd4674f6ab731d32fea64116997b05/upgrade.properties

@@ -0,0 +1,4 @@
+description: Introduce re-use expressions
+compatibility: partial
+expr_reuse.rel: delete
+exprs.rel: run exprs.qlo

cpp/downgrades/abfce5c170f93e281948f7689ece373464fdaf87/expr_reuse.ql

@@ -0,0 +1,7 @@
+class Expr extends @expr {
+  string toString() { none() }
+}
+
+from Expr reuse, Expr original
+where expr_reuse(reuse, original, _)
+select reuse, original

cpp/downgrades/abfce5c170f93e281948f7689ece373464fdaf87/expr_types.ql

@@ -0,0 +1,22 @@
+class Expr extends @expr {
+  string toString() { none() }
+}
+
+class Type extends @type {
+  string toString() { none() }
+}
+
+predicate existingType(Expr expr, Type type, int value_category) {
+  expr_types(expr, type, value_category)
+}
+
+predicate reuseType(Expr reuse, Type type, int value_category) {
+  exists(Expr original |
+    expr_reuse(reuse, original, value_category) and
+    expr_types(original, type, _)
+  )
+}
+
+from Expr expr, Type type, int value_category
+where existingType(expr, type, value_category) or reuseType(expr, type, value_category)
+select expr, type, value_category

cpp/downgrades/abfce5c170f93e281948f7689ece373464fdaf87/upgrade.properties

@@ -0,0 +1,4 @@
+description: Add value category to expr_reuse table
+compatibility: full
+expr_reuse.rel: run expr_reuse.qlo
+expr_types.rel: run expr_types.qlo

cpp/ql/lib/CHANGELOG.md

@@ -1,3 +1,32 @@
+## 0.12.10
+
+### New Features
+
+* Added a `TaintInheritingContent` class that can be extended to model taint flowing from a qualifier to a field.
+* Added a predicate `GuardCondition.comparesEq/4` to query whether an expression is compared to a constant. 
+* Added a predicate `GuardCondition.ensuresEq/4` to query whether a basic block is guarded by an expression being equal to a constant.
+* Added a predicate `GuardCondition.comparesLt/4` to query whether an expression is compared to a constant. 
+* Added a predicate `GuardCondition.ensuresLt/4` to query whether a basic block is guarded by an expression being less than a constant.
+* Added a predicate `GuardCondition.valueControls` to query whether a basic block is guarded by a particular `case` of a `switch` statement.
+
+### Minor Analysis Improvements
+
+* Added destructors for temporary objects with extended lifetimes to the intermediate representation.
+
+## 0.12.9
+
+No user-facing changes.
+
+## 0.12.8
+
+No user-facing changes.
+
+## 0.12.7
+
+### Minor Analysis Improvements
+
+* Added destructors for named objects to the intermediate representation.
+
 ## 0.12.6
 
 ### New Features

cpp/ql/lib/change-notes/released/0.12.10.md

@@ -0,0 +1,14 @@
+## 0.12.10
+
+### New Features
+
+* Added a `TaintInheritingContent` class that can be extended to model taint flowing from a qualifier to a field.
+* Added a predicate `GuardCondition.comparesEq/4` to query whether an expression is compared to a constant. 
+* Added a predicate `GuardCondition.ensuresEq/4` to query whether a basic block is guarded by an expression being equal to a constant.
+* Added a predicate `GuardCondition.comparesLt/4` to query whether an expression is compared to a constant. 
+* Added a predicate `GuardCondition.ensuresLt/4` to query whether a basic block is guarded by an expression being less than a constant.
+* Added a predicate `GuardCondition.valueControls` to query whether a basic block is guarded by a particular `case` of a `switch` statement.
+
+### Minor Analysis Improvements
+
+* Added destructors for temporary objects with extended lifetimes to the intermediate representation.

cpp/ql/lib/change-notes/released/0.12.7.md

@@ -1,4 +1,5 @@
----
-category: minorAnalysis
----
-* Added destructors for named objects to the intermediate representation.
+## 0.12.7
+
+### Minor Analysis Improvements
+
+* Added destructors for named objects to the intermediate representation.

cpp/ql/lib/change-notes/released/0.12.8.md

@@ -0,0 +1,3 @@
+## 0.12.8
+
+No user-facing changes.

cpp/ql/lib/change-notes/released/0.12.9.md

@@ -0,0 +1,3 @@
+## 0.12.9
+
+No user-facing changes.

cpp/ql/lib/codeql-pack.release.yml

@@ -1,2 +1,2 @@
 ---
-lastReleaseVersion: 0.12.6
+lastReleaseVersion: 0.12.10

cpp/ql/lib/qlpack.yml

@@ -1,5 +1,5 @@
 name: codeql/cpp-all
-version: 0.12.7-dev
+version: 0.12.10
 groups: cpp
 dbscheme: semmlecode.cpp.dbscheme
 extractor: cpp

cpp/ql/lib/semmle/code/cpp/PrintAST.qll

@@ -309,9 +309,12 @@ class ExprNode extends AstNode {
   override AstNode getChildInternal(int childIndex) {
     result.getAst() = expr.getChild(childIndex)
     or
+    childIndex = max(int index | exists(expr.getChild(index)) or index = 0) + 1 and
+    result.getAst() = expr.(ConditionDeclExpr).getInitializingExpr()
+    or
     exists(int destructorIndex |
       result.getAst() = expr.getImplicitDestructorCall(destructorIndex) and
-      childIndex = destructorIndex + max(int index | exists(expr.getChild(index)) or index = 0) + 1
+      childIndex = destructorIndex + max(int index | exists(expr.getChild(index)) or index = 0) + 2
     )
   }
 
@@ -686,6 +689,8 @@ private string getChildAccessorWithoutConversions(Locatable parent, Element chil
       not namedExprChildPredicates(expr, child, _) and
       exists(int n | expr.getChild(n) = child and result = "getChild(" + n + ")")
       or
+      expr.(ConditionDeclExpr).getInitializingExpr() = child and result = "getInitializingExpr()"
+      or
       exists(int n |
         expr.getImplicitDestructorCall(n) = child and
         result = "getImplicitDestructorCall(" + n + ")"

cpp/ql/lib/semmle/code/cpp/Variable.qll

@@ -590,6 +590,33 @@ class TemplateVariable extends Variable {
   Variable getAnInstantiation() { result.isConstructedFrom(this) }
 }
 
+/**
+ * A variable that is an instantiation of a template. For example
+ * the instantiation `myTemplateVariable<int>` in the following code:
+ * ```
+ * template<class T>
+ * T myTemplateVariable;
+ *
+ * void caller(int i) {
+ *   myTemplateVariable<int> = i;
+ * }
+ * ```
+ */
+class VariableTemplateInstantiation extends Variable {
+  TemplateVariable tv;
+
+  VariableTemplateInstantiation() { tv.getAnInstantiation() = this }
+
+  override string getAPrimaryQlClass() { result = "VariableTemplateInstantiation" }
+
+  /**
+   * Gets the variable template from which this instantiation was instantiated.
+   *
+   * Example: For `int x<int>`, returns `T x`.
+   */
+  TemplateVariable getTemplate() { result = tv }
+}
+
 /**
  * A non-static local variable or parameter that is not part of an
  * uninstantiated template. Uninstantiated templates are purely syntax, and

cpp/ql/lib/semmle/code/cpp/controlflow/IRGuards.qll

@@ -20,6 +20,44 @@ private predicate isUnreachedBlock(IRBlock block) {
   block.getFirstInstruction() instanceof UnreachedInstruction
 }
 
+private newtype TAbstractValue =
+  TBooleanValue(boolean b) { b = true or b = false } or
+  TMatchValue(CaseEdge c)
+
+/**
+ * An abstract value. This is either a boolean value, or a `switch` case.
+ */
+abstract class AbstractValue extends TAbstractValue {
+  /** Gets an abstract value that represents the dual of this value, if any. */
+  abstract AbstractValue getDualValue();
+
+  /** Gets a textual representation of this abstract value. */
+  abstract string toString();
+}
+
+/** A Boolean value. */
+class BooleanValue extends AbstractValue, TBooleanValue {
+  /** Gets the underlying Boolean value. */
+  boolean getValue() { this = TBooleanValue(result) }
+
+  override BooleanValue getDualValue() { result.getValue() = this.getValue().booleanNot() }
+
+  override string toString() { result = this.getValue().toString() }
+}
+
+/** A value that represents a match against a specific `switch` case. */
+class MatchValue extends AbstractValue, TMatchValue {
+  /** Gets the case. */
+  CaseEdge getCase() { this = TMatchValue(result) }
+
+  override MatchValue getDualValue() {
+    // A `MatchValue` has no dual.
+    none()
+  }
+
+  override string toString() { result = this.getCase().toString() }
+}
+
 /**
  * A Boolean condition in the AST that guards one or more basic blocks. This includes
  * operands of logical operators but not switch statements.
@@ -34,6 +72,15 @@ class GuardCondition extends Expr {
     this.(BinaryLogicalOperation).getAnOperand() instanceof GuardCondition
   }
 
+  /**
+   * Holds if this condition controls `controlled`, meaning that `controlled` is only
+   * entered if the value of this condition is `v`.
+   *
+   * For details on what "controls" mean, see the QLDoc for `controls`.
+   */
+  cached
+  predicate valueControls(BasicBlock controlled, AbstractValue v) { none() }
+
   /**
    * Holds if this condition controls `controlled`, meaning that `controlled` is only
    * entered if the value of this condition is `testIsTrue`.
@@ -61,7 +108,9 @@ class GuardCondition extends Expr {
    * true (for `&&`) or false (for `||`) branch.
    */
   cached
-  predicate controls(BasicBlock controlled, boolean testIsTrue) { none() }
+  final predicate controls(BasicBlock controlled, boolean testIsTrue) {
+    this.valueControls(controlled, any(BooleanValue bv | bv.getValue() = testIsTrue))
+  }
 
   /** Holds if (determined by this guard) `left < right + k` evaluates to `isLessThan` if this expression evaluates to `testIsTrue`. */
   cached
@@ -76,6 +125,20 @@ class GuardCondition extends Expr {
   cached
   predicate ensuresLt(Expr left, Expr right, int k, BasicBlock block, boolean isLessThan) { none() }
 
+  /**
+   * Holds if (determined by this guard) `e < k` evaluates to `isLessThan` if
+   * this expression evaluates to `value`.
+   */
+  cached
+  predicate comparesLt(Expr e, int k, boolean isLessThan, AbstractValue value) { none() }
+
+  /**
+   * Holds if (determined by this guard) `e < k` must be `isLessThan` in `block`.
+   * If `isLessThan = false` then this implies `e >= k`.
+   */
+  cached
+  predicate ensuresLt(Expr e, int k, BasicBlock block, boolean isLessThan) { none() }
+
   /** Holds if (determined by this guard) `left == right + k` evaluates to `areEqual` if this expression evaluates to `testIsTrue`. */
   cached
   predicate comparesEq(Expr left, Expr right, int k, boolean areEqual, boolean testIsTrue) {
@@ -88,6 +151,17 @@ class GuardCondition extends Expr {
    */
   cached
   predicate ensuresEq(Expr left, Expr right, int k, BasicBlock block, boolean areEqual) { none() }
+
+  /** Holds if (determined by this guard) `e == k` evaluates to `areEqual` if this expression evaluates to `value`. */
+  cached
+  predicate comparesEq(Expr e, int k, boolean areEqual, AbstractValue value) { none() }
+
+  /**
+   * Holds if (determined by this guard) `e == k` must be `areEqual` in `block`.
+   * If `areEqual = false` then this implies `e != k`.
+   */
+  cached
+  predicate ensuresEq(Expr e, int k, BasicBlock block, boolean areEqual) { none() }
 }
 
 /**
@@ -98,13 +172,13 @@ private class GuardConditionFromBinaryLogicalOperator extends GuardCondition {
     this.(BinaryLogicalOperation).getAnOperand() instanceof GuardCondition
   }
 
-  override predicate controls(BasicBlock controlled, boolean testIsTrue) {
+  override predicate valueControls(BasicBlock controlled, AbstractValue v) {
     exists(BinaryLogicalOperation binop, GuardCondition lhs, GuardCondition rhs |
       this = binop and
       lhs = binop.getLeftOperand() and
       rhs = binop.getRightOperand() and
-      lhs.controls(controlled, testIsTrue) and
-      rhs.controls(controlled, testIsTrue)
+      lhs.valueControls(controlled, v) and
+      rhs.valueControls(controlled, v)
     )
   }
 
@@ -116,12 +190,27 @@ private class GuardConditionFromBinaryLogicalOperator extends GuardCondition {
     )
   }
 
+  override predicate comparesLt(Expr e, int k, boolean isLessThan, AbstractValue value) {
+    exists(BooleanValue partValue, GuardCondition part |
+      this.(BinaryLogicalOperation)
+          .impliesValue(part, partValue.getValue(), value.(BooleanValue).getValue())
+    |
+      part.comparesLt(e, k, isLessThan, partValue)
+    )
+  }
+
   override predicate ensuresLt(Expr left, Expr right, int k, BasicBlock block, boolean isLessThan) {
     exists(boolean testIsTrue |
       this.comparesLt(left, right, k, isLessThan, testIsTrue) and this.controls(block, testIsTrue)
     )
   }
 
+  override predicate ensuresLt(Expr e, int k, BasicBlock block, boolean isLessThan) {
+    exists(AbstractValue value |
+      this.comparesLt(e, k, isLessThan, value) and this.valueControls(block, value)
+    )
+  }
+
   override predicate comparesEq(Expr left, Expr right, int k, boolean areEqual, boolean testIsTrue) {
     exists(boolean partIsTrue, GuardCondition part |
       this.(BinaryLogicalOperation).impliesValue(part, partIsTrue, testIsTrue)
@@ -135,6 +224,21 @@ private class GuardConditionFromBinaryLogicalOperator extends GuardCondition {
       this.comparesEq(left, right, k, areEqual, testIsTrue) and this.controls(block, testIsTrue)
     )
   }
+
+  override predicate comparesEq(Expr e, int k, boolean areEqual, AbstractValue value) {
+    exists(BooleanValue partValue, GuardCondition part |
+      this.(BinaryLogicalOperation)
+          .impliesValue(part, partValue.getValue(), value.(BooleanValue).getValue())
+    |
+      part.comparesEq(e, k, areEqual, partValue)
+    )
+  }
+
+  override predicate ensuresEq(Expr e, int k, BasicBlock block, boolean areEqual) {
+    exists(AbstractValue value |
+      this.comparesEq(e, k, areEqual, value) and this.valueControls(block, value)
+    )
+  }
 }
 
 /**
@@ -146,13 +250,12 @@ private class GuardConditionFromIR extends GuardCondition {
 
   GuardConditionFromIR() { this = ir.getUnconvertedResultExpression() }
 
-  override predicate controls(BasicBlock controlled, boolean testIsTrue) {
+  override predicate valueControls(BasicBlock controlled, AbstractValue v) {
     // This condition must determine the flow of control; that is, this
     // node must be a top-level condition.
-    this.controlsBlock(controlled, testIsTrue)
+    this.controlsBlock(controlled, v)
   }
 
-  /** Holds if (determined by this guard) `left < right + k` evaluates to `isLessThan` if this expression evaluates to `testIsTrue`. */
   override predicate comparesLt(Expr left, Expr right, int k, boolean isLessThan, boolean testIsTrue) {
     exists(Instruction li, Instruction ri |
       li.getUnconvertedResultExpression() = left and
@@ -161,10 +264,13 @@ private class GuardConditionFromIR extends GuardCondition {
     )
   }
 
-  /**
-   * Holds if (determined by this guard) `left < right + k` must be `isLessThan` in `block`.
-   * If `isLessThan = false` then this implies `left >= right + k`.
-   */
+  override predicate comparesLt(Expr e, int k, boolean isLessThan, AbstractValue value) {
+    exists(Instruction i |
+      i.getUnconvertedResultExpression() = e and
+      ir.comparesLt(i.getAUse(), k, isLessThan, value)
+    )
+  }
+
   override predicate ensuresLt(Expr left, Expr right, int k, BasicBlock block, boolean isLessThan) {
     exists(Instruction li, Instruction ri, boolean testIsTrue |
       li.getUnconvertedResultExpression() = left and
@@ -174,7 +280,14 @@ private class GuardConditionFromIR extends GuardCondition {
     )
   }
 
-  /** Holds if (determined by this guard) `left == right + k` evaluates to `areEqual` if this expression evaluates to `testIsTrue`. */
+  override predicate ensuresLt(Expr e, int k, BasicBlock block, boolean isLessThan) {
+    exists(Instruction i, AbstractValue value |
+      i.getUnconvertedResultExpression() = e and
+      ir.comparesLt(i.getAUse(), k, isLessThan, value) and
+      this.valueControls(block, value)
+    )
+  }
+
   override predicate comparesEq(Expr left, Expr right, int k, boolean areEqual, boolean testIsTrue) {
     exists(Instruction li, Instruction ri |
       li.getUnconvertedResultExpression() = left and
@@ -183,10 +296,6 @@ private class GuardConditionFromIR extends GuardCondition {
     )
   }
 
-  /**
-   * Holds if (determined by this guard) `left == right + k` must be `areEqual` in `block`.
-   * If `areEqual = false` then this implies `left != right + k`.
-   */
   override predicate ensuresEq(Expr left, Expr right, int k, BasicBlock block, boolean areEqual) {
     exists(Instruction li, Instruction ri, boolean testIsTrue |
       li.getUnconvertedResultExpression() = left and
@@ -196,15 +305,30 @@ private class GuardConditionFromIR extends GuardCondition {
     )
   }
 
+  override predicate comparesEq(Expr e, int k, boolean areEqual, AbstractValue value) {
+    exists(Instruction i |
+      i.getUnconvertedResultExpression() = e and
+      ir.comparesEq(i.getAUse(), k, areEqual, value)
+    )
+  }
+
+  override predicate ensuresEq(Expr e, int k, BasicBlock block, boolean areEqual) {
+    exists(Instruction i, AbstractValue value |
+      i.getUnconvertedResultExpression() = e and
+      ir.comparesEq(i.getAUse(), k, areEqual, value) and
+      this.valueControls(block, value)
+    )
+  }
+
   /**
    * Holds if this condition controls `block`, meaning that `block` is only
-   * entered if the value of this condition is `testIsTrue`. This helper
+   * entered if the value of this condition is `v`. This helper
    * predicate does not necessarily hold for binary logical operations like
    * `&&` and `||`. See the detailed explanation on predicate `controls`.
    */
-  private predicate controlsBlock(BasicBlock controlled, boolean testIsTrue) {
+  private predicate controlsBlock(BasicBlock controlled, AbstractValue v) {
     exists(IRBlock irb |
-      ir.controls(irb, testIsTrue) and
+      ir.valueControls(irb, v) and
       nonExcludedIRAndBasicBlock(irb, controlled) and
       not isUnreachedBlock(irb)
     )
@@ -249,10 +373,28 @@ private predicate nonExcludedIRAndBasicBlock(IRBlock irb, BasicBlock controlled)
  */
 cached
 class IRGuardCondition extends Instruction {
-  ConditionalBranchInstruction branch;
+  Instruction branch;
 
   cached
-  IRGuardCondition() { branch = get_branch_for_condition(this) }
+  IRGuardCondition() { branch = getBranchForCondition(this) }
+
+  /**
+   * Holds if this condition controls `controlled`, meaning that `controlled` is only
+   * entered if the value of this condition is `v`.
+   *
+   * For details on what "controls" mean, see the QLDoc for `controls`.
+   */
+  cached
+  predicate valueControls(IRBlock controlled, AbstractValue v) {
+    // This condition must determine the flow of control; that is, this
+    // node must be a top-level condition.
+    this.controlsBlock(controlled, v)
+    or
+    exists(IRGuardCondition ne |
+      this = ne.(LogicalNotInstruction).getUnary() and
+      ne.valueControls(controlled, v.getDualValue())
+    )
+  }
 
   /**
    * Holds if this condition controls `controlled`, meaning that `controlled` is only
@@ -282,13 +424,25 @@ class IRGuardCondition extends Instruction {
    */
   cached
   predicate controls(IRBlock controlled, boolean testIsTrue) {
-    // This condition must determine the flow of control; that is, this
-    // node must be a top-level condition.
-    this.controlsBlock(controlled, testIsTrue)
+    this.valueControls(controlled, any(BooleanValue bv | bv.getValue() = testIsTrue))
+  }
+
+  /**
+   * Holds if the control-flow edge `(pred, succ)` may be taken only if
+   * the value of this condition is `v`.
+   */
+  cached
+  predicate valueControlsEdge(IRBlock pred, IRBlock succ, AbstractValue v) {
+    pred.getASuccessor() = succ and
+    this.valueControls(pred, v)
     or
-    exists(IRGuardCondition ne |
-      this = ne.(LogicalNotInstruction).getUnary() and
-      ne.controls(controlled, testIsTrue.booleanNot())
+    succ = this.getBranchSuccessor(v) and
+    (
+      branch.(ConditionalBranchInstruction).getCondition() = this and
+      branch.getBlock() = pred
+      or
+      branch.(SwitchInstruction).getExpression() = this and
+      branch.getBlock() = pred
     )
   }
 
@@ -297,17 +451,12 @@ class IRGuardCondition extends Instruction {
    * the value of this condition is `testIsTrue`.
    */
   cached
-  predicate controlsEdge(IRBlock pred, IRBlock succ, boolean testIsTrue) {
-    pred.getASuccessor() = succ and
-    this.controls(pred, testIsTrue)
-    or
-    succ = this.getBranchSuccessor(testIsTrue) and
-    branch.getCondition() = this and
-    branch.getBlock() = pred
+  final predicate controlsEdge(IRBlock pred, IRBlock succ, boolean testIsTrue) {
+    this.valueControlsEdge(pred, succ, any(BooleanValue bv | bv.getValue() = testIsTrue))
   }
 
   /**
-   * Gets the block to which `branch` jumps directly when this condition is `testIsTrue`.
+   * Gets the block to which `branch` jumps directly when the value of this condition is `v`.
    *
    * This predicate is intended to help with situations in which an inference can only be made
    * based on an edge between a block with multiple successors and a block with multiple
@@ -321,21 +470,39 @@ class IRGuardCondition extends Instruction {
    * return x;
    * ```
    */
-  private IRBlock getBranchSuccessor(boolean testIsTrue) {
-    branch.getCondition() = this and
-    (
-      testIsTrue = true and
-      result.getFirstInstruction() = branch.getTrueSuccessor()
+  private IRBlock getBranchSuccessor(AbstractValue v) {
+    branch.(ConditionalBranchInstruction).getCondition() = this and
+    exists(BooleanValue bv | bv = v |
+      bv.getValue() = true and
+      result.getFirstInstruction() = branch.(ConditionalBranchInstruction).getTrueSuccessor()
       or
-      testIsTrue = false and
-      result.getFirstInstruction() = branch.getFalseSuccessor()
+      bv.getValue() = false and
+      result.getFirstInstruction() = branch.(ConditionalBranchInstruction).getFalseSuccessor()
+    )
+    or
+    exists(SwitchInstruction switch, CaseEdge kind | switch = branch |
+      switch.getExpression() = this and
+      result.getFirstInstruction() = switch.getSuccessor(kind) and
+      kind = v.(MatchValue).getCase()
     )
   }
 
   /** Holds if (determined by this guard) `left < right + k` evaluates to `isLessThan` if this expression evaluates to `testIsTrue`. */
   cached
   predicate comparesLt(Operand left, Operand right, int k, boolean isLessThan, boolean testIsTrue) {
-    compares_lt(this, left, right, k, isLessThan, testIsTrue)
+    exists(BooleanValue value |
+      compares_lt(this, left, right, k, isLessThan, value) and
+      value.getValue() = testIsTrue
+    )
+  }
+
+  /**
+   * Holds if (determined by this guard) `op < k` evaluates to `isLessThan` if
+   * this expression evaluates to `value`.
+   */
+  cached
+  predicate comparesLt(Operand op, int k, boolean isLessThan, AbstractValue value) {
+    compares_lt(this, op, k, isLessThan, value)
   }
 
   /**
@@ -344,8 +511,19 @@ class IRGuardCondition extends Instruction {
    */
   cached
   predicate ensuresLt(Operand left, Operand right, int k, IRBlock block, boolean isLessThan) {
-    exists(boolean testIsTrue |
-      compares_lt(this, left, right, k, isLessThan, testIsTrue) and this.controls(block, testIsTrue)
+    exists(AbstractValue value |
+      compares_lt(this, left, right, k, isLessThan, value) and this.valueControls(block, value)
+    )
+  }
+
+  /**
+   * Holds if (determined by this guard) `op < k` must be `isLessThan` in `block`.
+   * If `isLessThan = false` then this implies `op >= k`.
+   */
+  cached
+  predicate ensuresLt(Operand op, int k, IRBlock block, boolean isLessThan) {
+    exists(AbstractValue value |
+      compares_lt(this, op, k, isLessThan, value) and this.valueControls(block, value)
     )
   }
 
@@ -357,16 +535,37 @@ class IRGuardCondition extends Instruction {
   predicate ensuresLtEdge(
     Operand left, Operand right, int k, IRBlock pred, IRBlock succ, boolean isLessThan
   ) {
-    exists(boolean testIsTrue |
-      compares_lt(this, left, right, k, isLessThan, testIsTrue) and
-      this.controlsEdge(pred, succ, testIsTrue)
+    exists(AbstractValue value |
+      compares_lt(this, left, right, k, isLessThan, value) and
+      this.valueControlsEdge(pred, succ, value)
+    )
+  }
+
+  /**
+   * Holds if (determined by this guard) `op < k` must be `isLessThan` on the edge from
+   * `pred` to `succ`. If `isLessThan = false` then this implies `op >= k`.
+   */
+  cached
+  predicate ensuresLtEdge(Operand left, int k, IRBlock pred, IRBlock succ, boolean isLessThan) {
+    exists(AbstractValue value |
+      compares_lt(this, left, k, isLessThan, value) and
+      this.valueControlsEdge(pred, succ, value)
     )
   }
 
   /** Holds if (determined by this guard) `left == right + k` evaluates to `areEqual` if this expression evaluates to `testIsTrue`. */
   cached
   predicate comparesEq(Operand left, Operand right, int k, boolean areEqual, boolean testIsTrue) {
-    compares_eq(this, left, right, k, areEqual, testIsTrue)
+    exists(BooleanValue value |
+      compares_eq(this, left, right, k, areEqual, value) and
+      value.getValue() = testIsTrue
+    )
+  }
+
+  /** Holds if (determined by this guard) `op == k` evaluates to `areEqual` if this expression evaluates to `value`. */
+  cached
+  predicate comparesEq(Operand op, int k, boolean areEqual, AbstractValue value) {
+    compares_eq(this, op, k, areEqual, value)
   }
 
   /**
@@ -375,8 +574,19 @@ class IRGuardCondition extends Instruction {
    */
   cached
   predicate ensuresEq(Operand left, Operand right, int k, IRBlock block, boolean areEqual) {
-    exists(boolean testIsTrue |
-      compares_eq(this, left, right, k, areEqual, testIsTrue) and this.controls(block, testIsTrue)
+    exists(AbstractValue value |
+      compares_eq(this, left, right, k, areEqual, value) and this.valueControls(block, value)
+    )
+  }
+
+  /**
+   * Holds if (determined by this guard) `op == k` must be `areEqual` in `block`.
+   * If `areEqual = false` then this implies `op != k`.
+   */
+  cached
+  predicate ensuresEq(Operand op, int k, IRBlock block, boolean areEqual) {
+    exists(AbstractValue value |
+      compares_eq(this, op, k, areEqual, value) and this.valueControls(block, value)
     )
   }
 
@@ -388,19 +598,31 @@ class IRGuardCondition extends Instruction {
   predicate ensuresEqEdge(
     Operand left, Operand right, int k, IRBlock pred, IRBlock succ, boolean areEqual
   ) {
-    exists(boolean testIsTrue |
-      compares_eq(this, left, right, k, areEqual, testIsTrue) and
-      this.controlsEdge(pred, succ, testIsTrue)
+    exists(AbstractValue value |
+      compares_eq(this, left, right, k, areEqual, value) and
+      this.valueControlsEdge(pred, succ, value)
+    )
+  }
+
+  /**
+   * Holds if (determined by this guard) `op == k` must be `areEqual` on the edge from
+   * `pred` to `succ`. If `areEqual = false` then this implies `op != k`.
+   */
+  cached
+  predicate ensuresEqEdge(Operand op, int k, IRBlock pred, IRBlock succ, boolean areEqual) {
+    exists(AbstractValue value |
+      compares_eq(this, op, k, areEqual, value) and
+      this.valueControlsEdge(pred, succ, value)
     )
   }
 
   /**
    * Holds if this condition controls `block`, meaning that `block` is only
-   * entered if the value of this condition is `testIsTrue`. This helper
+   * entered if the value of this condition is `v`. This helper
    * predicate does not necessarily hold for binary logical operations like
    * `&&` and `||`. See the detailed explanation on predicate `controls`.
    */
-  private predicate controlsBlock(IRBlock controlled, boolean testIsTrue) {
+  private predicate controlsBlock(IRBlock controlled, AbstractValue v) {
     not isUnreachedBlock(controlled) and
     //
     // For this block to control the block `controlled` with `testIsTrue` the
@@ -441,7 +663,7 @@ class IRGuardCondition extends Instruction {
     // that `this` strictly dominates `controlled` so that isn't necessary to check
     // directly.
     exists(IRBlock succ |
-      succ = this.getBranchSuccessor(testIsTrue) and
+      succ = this.getBranchSuccessor(v) and
       this.hasDominatingEdgeTo(succ) and
       succ.dominates(controlled)
     )
@@ -476,12 +698,14 @@ class IRGuardCondition extends Instruction {
   private IRBlock getBranchBlock() { result = branch.getBlock() }
 }
 
-private ConditionalBranchInstruction get_branch_for_condition(Instruction guard) {
-  result.getCondition() = guard
+private Instruction getBranchForCondition(Instruction guard) {
+  result.(ConditionalBranchInstruction).getCondition() = guard
   or
   exists(LogicalNotInstruction cond |
-    result = get_branch_for_condition(cond) and cond.getUnary() = guard
+    result = getBranchForCondition(cond) and cond.getUnary() = guard
   )
+  or
+  result.(SwitchInstruction).getExpression() = guard
 }
 
 /**
@@ -490,52 +714,98 @@ private ConditionalBranchInstruction get_branch_for_condition(Instruction guard)
  * Beware making mistaken logical implications here relating `areEqual` and `testIsTrue`.
  */
 private predicate compares_eq(
-  Instruction test, Operand left, Operand right, int k, boolean areEqual, boolean testIsTrue
+  Instruction test, Operand left, Operand right, int k, boolean areEqual, AbstractValue value
 ) {
   /* The simple case where the test *is* the comparison so areEqual = testIsTrue xor eq. */
-  exists(boolean eq | simple_comparison_eq(test, left, right, k, eq) |
-    areEqual = true and testIsTrue = eq
+  exists(AbstractValue v | simple_comparison_eq(test, left, right, k, v) |
+    areEqual = true and value = v
     or
-    areEqual = false and testIsTrue = eq.booleanNot()
+    areEqual = false and value = v.getDualValue()
   )
   or
   // I think this is handled by forwarding in controlsBlock.
   //or
   //logical_comparison_eq(test, left, right, k, areEqual, testIsTrue)
   /* a == b + k => b == a - k */
-  exists(int mk | k = -mk | compares_eq(test, right, left, mk, areEqual, testIsTrue))
+  exists(int mk | k = -mk | compares_eq(test, right, left, mk, areEqual, value))
   or
-  complex_eq(test, left, right, k, areEqual, testIsTrue)
+  complex_eq(test, left, right, k, areEqual, value)
   or
   /* (x is true => (left == right + k)) => (!x is false => (left == right + k)) */
-  exists(boolean isFalse | testIsTrue = isFalse.booleanNot() |
-    compares_eq(test.(LogicalNotInstruction).getUnary(), left, right, k, areEqual, isFalse)
+  exists(AbstractValue dual | value = dual.getDualValue() |
+    compares_eq(test.(LogicalNotInstruction).getUnary(), left, right, k, areEqual, dual)
+  )
+}
+
+/** Holds if `op == k` is `areEqual` given that `test` is equal to `value`. */
+private predicate compares_eq(
+  Instruction test, Operand op, int k, boolean areEqual, AbstractValue value
+) {
+  /* The simple case where the test *is* the comparison so areEqual = testIsTrue xor eq. */
+  exists(AbstractValue v | simple_comparison_eq(test, op, k, v) |
+    areEqual = true and value = v
+    or
+    areEqual = false and value = v.getDualValue()
+  )
+  or
+  complex_eq(test, op, k, areEqual, value)
+  or
+  /* (x is true => (op == k)) => (!x is false => (op == k)) */
+  exists(AbstractValue dual | value = dual.getDualValue() |
+    compares_eq(test.(LogicalNotInstruction).getUnary(), op, k, areEqual, dual)
+  )
+  or
+  // ((test is `areEqual` => op == const + k2) and const == `k1`) =>
+  // test is `areEqual` => op == k1 + k2
+  exists(int k1, int k2, ConstantInstruction const |
+    compares_eq(test, op, const.getAUse(), k2, areEqual, value) and
+    int_value(const) = k1 and
+    k = k1 + k2
   )
 }
 
 /** Rearrange various simple comparisons into `left == right + k` form. */
 private predicate simple_comparison_eq(
-  CompareInstruction cmp, Operand left, Operand right, int k, boolean areEqual
+  CompareInstruction cmp, Operand left, Operand right, int k, AbstractValue value
 ) {
   left = cmp.getLeftOperand() and
   cmp instanceof CompareEQInstruction and
   right = cmp.getRightOperand() and
   k = 0 and
-  areEqual = true
+  value.(BooleanValue).getValue() = true
   or
   left = cmp.getLeftOperand() and
   cmp instanceof CompareNEInstruction and
   right = cmp.getRightOperand() and
   k = 0 and
-  areEqual = false
+  value.(BooleanValue).getValue() = false
+}
+
+/** Rearrange various simple comparisons into `op == k` form. */
+private predicate simple_comparison_eq(Instruction test, Operand op, int k, AbstractValue value) {
+  exists(SwitchInstruction switch, CaseEdge case |
+    test = switch.getExpression() and
+    op.getDef() = test and
+    case = value.(MatchValue).getCase() and
+    exists(switch.getSuccessor(case)) and
+    case.getValue().toInt() = k
+  )
 }
 
 private predicate complex_eq(
-  CompareInstruction cmp, Operand left, Operand right, int k, boolean areEqual, boolean testIsTrue
+  CompareInstruction cmp, Operand left, Operand right, int k, boolean areEqual, AbstractValue value
 ) {
-  sub_eq(cmp, left, right, k, areEqual, testIsTrue)
+  sub_eq(cmp, left, right, k, areEqual, value)
   or
-  add_eq(cmp, left, right, k, areEqual, testIsTrue)
+  add_eq(cmp, left, right, k, areEqual, value)
+}
+
+private predicate complex_eq(
+  Instruction test, Operand op, int k, boolean areEqual, AbstractValue value
+) {
+  sub_eq(test, op, k, areEqual, value)
+  or
+  add_eq(test, op, k, areEqual, value)
 }
 
 /*
@@ -545,31 +815,46 @@ private predicate complex_eq(
 
 /** Holds if `left < right + k` evaluates to `isLt` given that test is `testIsTrue`. */
 private predicate compares_lt(
-  Instruction test, Operand left, Operand right, int k, boolean isLt, boolean testIsTrue
+  Instruction test, Operand left, Operand right, int k, boolean isLt, AbstractValue value
 ) {
   /* In the simple case, the test is the comparison, so isLt = testIsTrue */
-  simple_comparison_lt(test, left, right, k) and isLt = true and testIsTrue = true
+  simple_comparison_lt(test, left, right, k) and
+  value.(BooleanValue).getValue() = isLt
   or
-  simple_comparison_lt(test, left, right, k) and isLt = false and testIsTrue = false
-  or
-  complex_lt(test, left, right, k, isLt, testIsTrue)
+  complex_lt(test, left, right, k, isLt, value)
   or
   /* (not (left < right + k)) => (left >= right + k) */
-  exists(boolean isGe | isLt = isGe.booleanNot() |
-    compares_ge(test, left, right, k, isGe, testIsTrue)
-  )
+  exists(boolean isGe | isLt = isGe.booleanNot() | compares_ge(test, left, right, k, isGe, value))
   or
   /* (x is true => (left < right + k)) => (!x is false => (left < right + k)) */
-  exists(boolean isFalse | testIsTrue = isFalse.booleanNot() |
-    compares_lt(test.(LogicalNotInstruction).getUnary(), left, right, k, isLt, isFalse)
+  exists(AbstractValue dual | value = dual.getDualValue() |
+    compares_lt(test.(LogicalNotInstruction).getUnary(), left, right, k, isLt, dual)
+  )
+}
+
+/** Holds if `op < k` evaluates to `isLt` given that `test` evaluates to `value`. */
+private predicate compares_lt(Instruction test, Operand op, int k, boolean isLt, AbstractValue value) {
+  simple_comparison_lt(test, op, k, isLt, value)
+  or
+  complex_lt(test, op, k, isLt, value)
+  or
+  /* (x is true => (op < k)) => (!x is false => (op < k)) */
+  exists(AbstractValue dual | value = dual.getDualValue() |
+    compares_lt(test.(LogicalNotInstruction).getUnary(), op, k, isLt, dual)
+  )
+  or
+  exists(int k1, int k2, ConstantInstruction const |
+    compares_lt(test, op, const.getAUse(), k2, isLt, value) and
+    int_value(const) = k1 and
+    k = k1 + k2
   )
 }
 
 /** `(a < b + k) => (b > a - k) => (b >= a + (1-k))` */
 private predicate compares_ge(
-  Instruction test, Operand left, Operand right, int k, boolean isGe, boolean testIsTrue
+  Instruction test, Operand left, Operand right, int k, boolean isGe, AbstractValue value
 ) {
-  exists(int onemk | k = 1 - onemk | compares_lt(test, right, left, onemk, isGe, testIsTrue))
+  exists(int onemk | k = 1 - onemk | compares_lt(test, right, left, onemk, isGe, value))
 }
 
 /** Rearrange various simple comparisons into `left < right + k` form. */
@@ -595,55 +880,99 @@ private predicate simple_comparison_lt(CompareInstruction cmp, Operand left, Ope
   k = 1
 }
 
-private predicate complex_lt(
-  CompareInstruction cmp, Operand left, Operand right, int k, boolean isLt, boolean testIsTrue
+/** Rearrange various simple comparisons into `op < k` form. */
+private predicate simple_comparison_lt(
+  Instruction test, Operand op, int k, boolean isLt, AbstractValue value
 ) {
-  sub_lt(cmp, left, right, k, isLt, testIsTrue)
+  exists(SwitchInstruction switch, CaseEdge case |
+    test = switch.getExpression() and
+    op.getDef() = test and
+    case = value.(MatchValue).getCase() and
+    exists(switch.getSuccessor(case)) and
+    case.getMaxValue() > case.getMinValue()
+  |
+    // op <= k => op < k - 1
+    isLt = true and
+    case.getMaxValue().toInt() = k - 1
+    or
+    isLt = false and
+    case.getMinValue().toInt() = k
+  )
+}
+
+private predicate complex_lt(
+  CompareInstruction cmp, Operand left, Operand right, int k, boolean isLt, AbstractValue value
+) {
+  sub_lt(cmp, left, right, k, isLt, value)
   or
-  add_lt(cmp, left, right, k, isLt, testIsTrue)
+  add_lt(cmp, left, right, k, isLt, value)
+}
+
+private predicate complex_lt(
+  Instruction test, Operand left, int k, boolean isLt, AbstractValue value
+) {
+  sub_lt(test, left, k, isLt, value)
+  or
+  add_lt(test, left, k, isLt, value)
 }
 
 // left - x < right + c => left < right + (c+x)
 // left < (right - x) + c => left < right + (c-x)
 private predicate sub_lt(
-  CompareInstruction cmp, Operand left, Operand right, int k, boolean isLt, boolean testIsTrue
+  CompareInstruction cmp, Operand left, Operand right, int k, boolean isLt, AbstractValue value
 ) {
   exists(SubInstruction lhs, int c, int x |
-    compares_lt(cmp, lhs.getAUse(), right, c, isLt, testIsTrue) and
+    compares_lt(cmp, lhs.getAUse(), right, c, isLt, value) and
     left = lhs.getLeftOperand() and
     x = int_value(lhs.getRight()) and
     k = c + x
   )
   or
   exists(SubInstruction rhs, int c, int x |
-    compares_lt(cmp, left, rhs.getAUse(), c, isLt, testIsTrue) and
+    compares_lt(cmp, left, rhs.getAUse(), c, isLt, value) and
     right = rhs.getLeftOperand() and
     x = int_value(rhs.getRight()) and
     k = c - x
   )
   or
   exists(PointerSubInstruction lhs, int c, int x |
-    compares_lt(cmp, lhs.getAUse(), right, c, isLt, testIsTrue) and
+    compares_lt(cmp, lhs.getAUse(), right, c, isLt, value) and
     left = lhs.getLeftOperand() and
     x = int_value(lhs.getRight()) and
     k = c + x
   )
   or
   exists(PointerSubInstruction rhs, int c, int x |
-    compares_lt(cmp, left, rhs.getAUse(), c, isLt, testIsTrue) and
+    compares_lt(cmp, left, rhs.getAUse(), c, isLt, value) and
     right = rhs.getLeftOperand() and
     x = int_value(rhs.getRight()) and
     k = c - x
   )
 }
 
+private predicate sub_lt(Instruction test, Operand left, int k, boolean isLt, AbstractValue value) {
+  exists(SubInstruction lhs, int c, int x |
+    compares_lt(test, lhs.getAUse(), c, isLt, value) and
+    left = lhs.getLeftOperand() and
+    x = int_value(lhs.getRight()) and
+    k = c + x
+  )
+  or
+  exists(PointerSubInstruction lhs, int c, int x |
+    compares_lt(test, lhs.getAUse(), c, isLt, value) and
+    left = lhs.getLeftOperand() and
+    x = int_value(lhs.getRight()) and
+    k = c + x
+  )
+}
+
 // left + x < right + c => left < right + (c-x)
 // left < (right + x) + c => left < right + (c+x)
 private predicate add_lt(
-  CompareInstruction cmp, Operand left, Operand right, int k, boolean isLt, boolean testIsTrue
+  CompareInstruction cmp, Operand left, Operand right, int k, boolean isLt, AbstractValue value
 ) {
   exists(AddInstruction lhs, int c, int x |
-    compares_lt(cmp, lhs.getAUse(), right, c, isLt, testIsTrue) and
+    compares_lt(cmp, lhs.getAUse(), right, c, isLt, value) and
     (
       left = lhs.getLeftOperand() and x = int_value(lhs.getRight())
       or
@@ -653,7 +982,7 @@ private predicate add_lt(
   )
   or
   exists(AddInstruction rhs, int c, int x |
-    compares_lt(cmp, left, rhs.getAUse(), c, isLt, testIsTrue) and
+    compares_lt(cmp, left, rhs.getAUse(), c, isLt, value) and
     (
       right = rhs.getLeftOperand() and x = int_value(rhs.getRight())
       or
@@ -663,7 +992,7 @@ private predicate add_lt(
   )
   or
   exists(PointerAddInstruction lhs, int c, int x |
-    compares_lt(cmp, lhs.getAUse(), right, c, isLt, testIsTrue) and
+    compares_lt(cmp, lhs.getAUse(), right, c, isLt, value) and
     (
       left = lhs.getLeftOperand() and x = int_value(lhs.getRight())
       or
@@ -673,7 +1002,7 @@ private predicate add_lt(
   )
   or
   exists(PointerAddInstruction rhs, int c, int x |
-    compares_lt(cmp, left, rhs.getAUse(), c, isLt, testIsTrue) and
+    compares_lt(cmp, left, rhs.getAUse(), c, isLt, value) and
     (
       right = rhs.getLeftOperand() and x = int_value(rhs.getRight())
       or
@@ -683,47 +1012,86 @@ private predicate add_lt(
   )
 }
 
+private predicate add_lt(Instruction test, Operand left, int k, boolean isLt, AbstractValue value) {
+  exists(AddInstruction lhs, int c, int x |
+    compares_lt(test, lhs.getAUse(), c, isLt, value) and
+    (
+      left = lhs.getLeftOperand() and x = int_value(lhs.getRight())
+      or
+      left = lhs.getRightOperand() and x = int_value(lhs.getLeft())
+    ) and
+    k = c - x
+  )
+  or
+  exists(PointerAddInstruction lhs, int c, int x |
+    compares_lt(test, lhs.getAUse(), c, isLt, value) and
+    (
+      left = lhs.getLeftOperand() and x = int_value(lhs.getRight())
+      or
+      left = lhs.getRightOperand() and x = int_value(lhs.getLeft())
+    ) and
+    k = c - x
+  )
+}
+
 // left - x == right + c => left == right + (c+x)
 // left == (right - x) + c => left == right + (c-x)
 private predicate sub_eq(
-  CompareInstruction cmp, Operand left, Operand right, int k, boolean areEqual, boolean testIsTrue
+  CompareInstruction cmp, Operand left, Operand right, int k, boolean areEqual, AbstractValue value
 ) {
   exists(SubInstruction lhs, int c, int x |
-    compares_eq(cmp, lhs.getAUse(), right, c, areEqual, testIsTrue) and
+    compares_eq(cmp, lhs.getAUse(), right, c, areEqual, value) and
     left = lhs.getLeftOperand() and
     x = int_value(lhs.getRight()) and
     k = c + x
   )
   or
   exists(SubInstruction rhs, int c, int x |
-    compares_eq(cmp, left, rhs.getAUse(), c, areEqual, testIsTrue) and
+    compares_eq(cmp, left, rhs.getAUse(), c, areEqual, value) and
     right = rhs.getLeftOperand() and
     x = int_value(rhs.getRight()) and
     k = c - x
   )
   or
   exists(PointerSubInstruction lhs, int c, int x |
-    compares_eq(cmp, lhs.getAUse(), right, c, areEqual, testIsTrue) and
+    compares_eq(cmp, lhs.getAUse(), right, c, areEqual, value) and
     left = lhs.getLeftOperand() and
     x = int_value(lhs.getRight()) and
     k = c + x
   )
   or
   exists(PointerSubInstruction rhs, int c, int x |
-    compares_eq(cmp, left, rhs.getAUse(), c, areEqual, testIsTrue) and
+    compares_eq(cmp, left, rhs.getAUse(), c, areEqual, value) and
     right = rhs.getLeftOperand() and
     x = int_value(rhs.getRight()) and
     k = c - x
   )
 }
 
+// op - x == c => op == (c+x)
+private predicate sub_eq(Instruction test, Operand op, int k, boolean areEqual, AbstractValue value) {
+  exists(SubInstruction sub, int c, int x |
+    compares_eq(test, sub.getAUse(), c, areEqual, value) and
+    op = sub.getLeftOperand() and
+    x = int_value(sub.getRight()) and
+    k = c + x
+  )
+  or
+  exists(PointerSubInstruction sub, int c, int x |
+    compares_eq(test, sub.getAUse(), c, areEqual, value) and
+    op = sub.getLeftOperand() and
+    x = int_value(sub.getRight()) and
+    k = c + x
+  )
+}
+
 // left + x == right + c => left == right + (c-x)
 // left == (right + x) + c => left == right + (c+x)
 private predicate add_eq(
-  CompareInstruction cmp, Operand left, Operand right, int k, boolean areEqual, boolean testIsTrue
+  CompareInstruction cmp, Operand left, Operand right, int k, boolean areEqual, AbstractValue value
 ) {
   exists(AddInstruction lhs, int c, int x |
-    compares_eq(cmp, lhs.getAUse(), right, c, areEqual, testIsTrue) and
+    compares_eq(cmp, lhs.getAUse(), right, c, areEqual, value) and
     (
       left = lhs.getLeftOperand() and x = int_value(lhs.getRight())
       or
@@ -733,7 +1101,7 @@ private predicate add_eq(
   )
   or
   exists(AddInstruction rhs, int c, int x |
-    compares_eq(cmp, left, rhs.getAUse(), c, areEqual, testIsTrue) and
+    compares_eq(cmp, left, rhs.getAUse(), c, areEqual, value) and
     (
       right = rhs.getLeftOperand() and x = int_value(rhs.getRight())
       or
@@ -743,7 +1111,7 @@ private predicate add_eq(
   )
   or
   exists(PointerAddInstruction lhs, int c, int x |
-    compares_eq(cmp, lhs.getAUse(), right, c, areEqual, testIsTrue) and
+    compares_eq(cmp, lhs.getAUse(), right, c, areEqual, value) and
     (
       left = lhs.getLeftOperand() and x = int_value(lhs.getRight())
       or
@@ -753,7 +1121,7 @@ private predicate add_eq(
   )
   or
   exists(PointerAddInstruction rhs, int c, int x |
-    compares_eq(cmp, left, rhs.getAUse(), c, areEqual, testIsTrue) and
+    compares_eq(cmp, left, rhs.getAUse(), c, areEqual, value) and
     (
       right = rhs.getLeftOperand() and x = int_value(rhs.getRight())
       or
@@ -763,5 +1131,30 @@ private predicate add_eq(
   )
 }
 
+// left + x == right + c => left == right + (c-x)
+private predicate add_eq(
+  Instruction test, Operand left, int k, boolean areEqual, AbstractValue value
+) {
+  exists(AddInstruction lhs, int c, int x |
+    compares_eq(test, lhs.getAUse(), c, areEqual, value) and
+    (
+      left = lhs.getLeftOperand() and x = int_value(lhs.getRight())
+      or
+      left = lhs.getRightOperand() and x = int_value(lhs.getLeft())
+    ) and
+    k = c - x
+  )
+  or
+  exists(PointerAddInstruction lhs, int c, int x |
+    compares_eq(test, lhs.getAUse(), c, areEqual, value) and
+    (
+      left = lhs.getLeftOperand() and x = int_value(lhs.getRight())
+      or
+      left = lhs.getRightOperand() and x = int_value(lhs.getLeft())
+    ) and
+    k = c - x
+  )
+}
+
 /** The int value of integer constant expression. */
 private int int_value(Instruction i) { result = i.(IntegerConstantInstruction).getValue().toInt() }

cpp/ql/lib/semmle/code/cpp/dataflow/DataFlow.qll

@@ -28,6 +28,6 @@ import cpp
 deprecated module DataFlow {
   private import semmle.code.cpp.dataflow.internal.DataFlowImplSpecific
   private import codeql.dataflow.DataFlow
-  import DataFlowMake<CppOldDataFlow>
+  import DataFlowMake<Location, CppOldDataFlow>
   import semmle.code.cpp.dataflow.internal.DataFlowImpl1
 }

cpp/ql/lib/semmle/code/cpp/dataflow/TaintTracking.qll

@@ -29,6 +29,6 @@ deprecated module TaintTracking {
   private import semmle.code.cpp.dataflow.internal.DataFlowImplSpecific
   private import semmle.code.cpp.dataflow.internal.TaintTrackingImplSpecific
   private import codeql.dataflow.TaintTracking
-  import TaintFlowMake<CppOldDataFlow, CppOldTaintTracking>
+  import TaintFlowMake<Location, CppOldDataFlow, CppOldTaintTracking>
   import semmle.code.cpp.dataflow.internal.tainttracking1.TaintTrackingImpl
 }

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

@@ -2,6 +2,7 @@
  * DEPRECATED: Use `semmle.code.cpp.dataflow.new.DataFlow` instead.
  */
 
+private import semmle.code.cpp.Location
 private import DataFlowImplSpecific
 private import codeql.dataflow.internal.DataFlowImpl
-import MakeImpl<CppOldDataFlow>
+import MakeImpl<Location, CppOldDataFlow>

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl1.qll

@@ -285,6 +285,8 @@ deprecated private module Config implements FullStateConfigSig {
 
   int fieldFlowBranchLimit() { result = min(any(Configuration config).fieldFlowBranchLimit()) }
 
+  int accessPathLimit() { result = 5 }
+
   FlowFeature getAFeature() { result = any(Configuration config).getAFeature() }
 
   predicate sourceGrouping(Node source, string sourceGroup) {

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

@@ -285,6 +285,8 @@ deprecated private module Config implements FullStateConfigSig {
 
   int fieldFlowBranchLimit() { result = min(any(Configuration config).fieldFlowBranchLimit()) }
 
+  int accessPathLimit() { result = 5 }
+
   FlowFeature getAFeature() { result = any(Configuration config).getAFeature() }
 
   predicate sourceGrouping(Node source, string sourceGroup) {

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

@@ -285,6 +285,8 @@ deprecated private module Config implements FullStateConfigSig {
 
   int fieldFlowBranchLimit() { result = min(any(Configuration config).fieldFlowBranchLimit()) }
 
+  int accessPathLimit() { result = 5 }
+
   FlowFeature getAFeature() { result = any(Configuration config).getAFeature() }
 
   predicate sourceGrouping(Node source, string sourceGroup) {

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

@@ -285,6 +285,8 @@ deprecated private module Config implements FullStateConfigSig {
 
   int fieldFlowBranchLimit() { result = min(any(Configuration config).fieldFlowBranchLimit()) }
 
+  int accessPathLimit() { result = 5 }
+
   FlowFeature getAFeature() { result = any(Configuration config).getAFeature() }
 
   predicate sourceGrouping(Node source, string sourceGroup) {

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

@@ -2,6 +2,7 @@
  * DEPRECATED: Use `semmle.code.cpp.dataflow.new.DataFlow` instead.
  */
 
+private import semmle.code.cpp.Location
 private import DataFlowImplSpecific
 private import codeql.dataflow.internal.DataFlowImplCommon
-import MakeImplCommon<CppOldDataFlow>
+import MakeImplCommon<Location, CppOldDataFlow>

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImplConsistency.qll

@@ -10,7 +10,7 @@ private import DataFlowImplSpecific
 private import TaintTrackingImplSpecific
 private import codeql.dataflow.internal.DataFlowImplConsistency
 
-private module Input implements InputSig<CppOldDataFlow> {
+private module Input implements InputSig<Location, CppOldDataFlow> {
   predicate argHasPostUpdateExclude(Private::ArgumentNode n) {
     // Is the null pointer (or something that's not really a pointer)
     exists(n.asExpr().getValue())
@@ -26,4 +26,4 @@ private module Input implements InputSig<CppOldDataFlow> {
   }
 }
 
-module Consistency = MakeConsistency<CppOldDataFlow, CppOldTaintTracking, Input>;
+module Consistency = MakeConsistency<Location, CppOldDataFlow, CppOldTaintTracking, Input>;

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

@@ -285,6 +285,8 @@ deprecated private module Config implements FullStateConfigSig {
 
   int fieldFlowBranchLimit() { result = min(any(Configuration config).fieldFlowBranchLimit()) }
 
+  int accessPathLimit() { result = 5 }
+
   FlowFeature getAFeature() { result = any(Configuration config).getAFeature() }
 
   predicate sourceGrouping(Node source, string sourceGroup) {

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImplSpecific.qll

@@ -4,6 +4,7 @@
  * Provides C++-specific definitions for use in the data flow library.
  */
 
+private import semmle.code.cpp.Location
 private import codeql.dataflow.DataFlow
 
 module Private {
@@ -15,7 +16,7 @@ module Public {
   import DataFlowUtil
 }
 
-module CppOldDataFlow implements InputSig {
+module CppOldDataFlow implements InputSig<Location> {
   import Private
   import Public
 

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowUtil.qll

@@ -105,7 +105,7 @@ class Node extends TNode {
    * For more information, see
    * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
-  predicate hasLocationInfo(
+  deprecated predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
   ) {
     this.getLocation().hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)

cpp/ql/lib/semmle/code/cpp/dataflow/internal/TaintTrackingImplSpecific.qll

@@ -4,9 +4,10 @@
  * Provides C++-specific definitions for use in the taint tracking library.
  */
 
+private import semmle.code.cpp.Location
 private import codeql.dataflow.TaintTracking
 private import DataFlowImplSpecific
 
-module CppOldTaintTracking implements InputSig<CppOldDataFlow> {
+module CppOldTaintTracking implements InputSig<Location, CppOldDataFlow> {
   import TaintTrackingUtil
 }

cpp/ql/lib/semmle/code/cpp/dataflow/new/DataFlow.qll

@@ -28,6 +28,6 @@ import cpp
 module DataFlow {
   private import semmle.code.cpp.ir.dataflow.internal.DataFlowImplSpecific
   private import codeql.dataflow.DataFlow
-  import DataFlowMake<CppDataFlow>
+  import DataFlowMake<Location, CppDataFlow>
   import semmle.code.cpp.ir.dataflow.internal.DataFlowImpl1
 }

cpp/ql/lib/semmle/code/cpp/dataflow/new/TaintTracking.qll

@@ -27,6 +27,7 @@ module TaintTracking {
   private import semmle.code.cpp.ir.dataflow.internal.DataFlowImplSpecific
   private import semmle.code.cpp.ir.dataflow.internal.TaintTrackingImplSpecific
   private import codeql.dataflow.TaintTracking
-  import TaintFlowMake<CppDataFlow, CppTaintTracking>
+  private import semmle.code.cpp.Location
+  import TaintFlowMake<Location, CppDataFlow, CppTaintTracking>
   import semmle.code.cpp.ir.dataflow.internal.tainttracking1.TaintTrackingImpl
 }

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

@@ -1322,3 +1322,31 @@ class CoYieldExpr extends UnaryOperation, @co_yield {
 
   override int getPrecedence() { result = 2 }
 }
+
+/**
+ * An expression representing the re-use of another expression.
+ *
+ * In some specific cases an expression may be referred to outside its
+ * original context. A re-use expression wraps any such reference. A
+ * re-use expression can for example occur as the qualifier of an implicit
+ * destructor called on a temporary object, where the original use of the
+ * expression is in the definition of the temporary.
+ */
+class ReuseExpr extends Expr, @reuseexpr {
+  override string getAPrimaryQlClass() { result = "ReuseExpr" }
+
+  override string toString() { result = "reuse of " + this.getReusedExpr().toString() }
+
+  /**
+   * Gets the expression that is being re-used.
+   */
+  Expr getReusedExpr() { expr_reuse(underlyingElement(this), unresolveElement(result), _) }
+
+  override Type getType() { result = this.getReusedExpr().getType() }
+
+  override predicate isLValueCategory() { expr_reuse(underlyingElement(this), _, 3) }
+
+  override predicate isXValueCategory() { expr_reuse(underlyingElement(this), _, 2) }
+
+  override predicate isPRValueCategory() { expr_reuse(underlyingElement(this), _, 1) }
+}

cpp/ql/lib/semmle/code/cpp/ir/dataflow/DataFlow.qll

@@ -24,6 +24,6 @@ import cpp
 module DataFlow {
   private import semmle.code.cpp.ir.dataflow.internal.DataFlowImplSpecific
   private import codeql.dataflow.DataFlow
-  import DataFlowMake<CppDataFlow>
+  import DataFlowMake<Location, CppDataFlow>
   import semmle.code.cpp.ir.dataflow.internal.DataFlowImpl1
 }

cpp/ql/lib/semmle/code/cpp/ir/dataflow/FlowSteps.qll

@@ -0,0 +1,20 @@
+/**
+ * This file provides an abstract class that can be used to model additional
+ * object-to-field taint-flow.
+ */
+
+private import codeql.util.Unit
+private import semmle.code.cpp.dataflow.new.DataFlow
+
+/**
+ * A `Content` that should be implicitly regarded as tainted whenever an object with such `Content`
+ * is itself tainted.
+ *
+ * For example, if we had a type `struct Container { int field; }`, then by default a tainted
+ * `Container` and a `Container` with a tainted `int` stored in its `field` are distinct.
+ *
+ * If `any(DataFlow::FieldContent fc | fc.getField().hasQualifiedName("Container", "field"))` was
+ * included in this type however, then a tainted `Container` would imply that its `field` is also
+ * tainted (but not vice versa).
+ */
+abstract class TaintInheritingContent extends DataFlow::Content { }

cpp/ql/lib/semmle/code/cpp/ir/dataflow/TaintTracking.qll

@@ -23,6 +23,6 @@ module TaintTracking {
   private import semmle.code.cpp.ir.dataflow.internal.DataFlowImplSpecific
   private import semmle.code.cpp.ir.dataflow.internal.TaintTrackingImplSpecific
   private import codeql.dataflow.TaintTracking
-  import TaintFlowMake<CppDataFlow, CppTaintTracking>
+  import TaintFlowMake<Location, CppDataFlow, CppTaintTracking>
   import semmle.code.cpp.ir.dataflow.internal.tainttracking1.TaintTrackingImpl
 }

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

@@ -1,3 +1,4 @@
+private import semmle.code.cpp.Location
 private import DataFlowImplSpecific
 private import codeql.dataflow.internal.DataFlowImpl
-import MakeImpl<CppDataFlow>
+import MakeImpl<Location, CppDataFlow>

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl1.qll

@@ -285,6 +285,8 @@ deprecated private module Config implements FullStateConfigSig {
 
   int fieldFlowBranchLimit() { result = min(any(Configuration config).fieldFlowBranchLimit()) }
 
+  int accessPathLimit() { result = 5 }
+
   FlowFeature getAFeature() { result = any(Configuration config).getAFeature() }
 
   predicate sourceGrouping(Node source, string sourceGroup) {

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

@@ -285,6 +285,8 @@ deprecated private module Config implements FullStateConfigSig {
 
   int fieldFlowBranchLimit() { result = min(any(Configuration config).fieldFlowBranchLimit()) }
 
+  int accessPathLimit() { result = 5 }
+
   FlowFeature getAFeature() { result = any(Configuration config).getAFeature() }
 
   predicate sourceGrouping(Node source, string sourceGroup) {

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

@@ -285,6 +285,8 @@ deprecated private module Config implements FullStateConfigSig {
 
   int fieldFlowBranchLimit() { result = min(any(Configuration config).fieldFlowBranchLimit()) }
 
+  int accessPathLimit() { result = 5 }
+
   FlowFeature getAFeature() { result = any(Configuration config).getAFeature() }
 
   predicate sourceGrouping(Node source, string sourceGroup) {

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

@@ -285,6 +285,8 @@ deprecated private module Config implements FullStateConfigSig {
 
   int fieldFlowBranchLimit() { result = min(any(Configuration config).fieldFlowBranchLimit()) }
 
+  int accessPathLimit() { result = 5 }
+
   FlowFeature getAFeature() { result = any(Configuration config).getAFeature() }
 
   predicate sourceGrouping(Node source, string sourceGroup) {

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

@@ -1,3 +1,4 @@
+private import semmle.code.cpp.Location
 private import DataFlowImplSpecific
 private import codeql.dataflow.internal.DataFlowImplCommon
-import MakeImplCommon<CppDataFlow>
+import MakeImplCommon<Location, CppDataFlow>

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImplConsistency.qll

@@ -8,7 +8,7 @@ private import DataFlowImplSpecific
 private import TaintTrackingImplSpecific
 private import codeql.dataflow.internal.DataFlowImplConsistency
 
-private module Input implements InputSig<CppDataFlow> {
+private module Input implements InputSig<Location, CppDataFlow> {
   predicate argHasPostUpdateExclude(Private::ArgumentNode n) {
     // The rules for whether an IR argument gets a post-update node are too
     // complex to model here.
@@ -16,4 +16,4 @@ private module Input implements InputSig<CppDataFlow> {
   }
 }
 
-module Consistency = MakeConsistency<CppDataFlow, CppTaintTracking, Input>;
+module Consistency = MakeConsistency<Location, CppDataFlow, CppTaintTracking, Input>;

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImplSpecific.qll

@@ -3,6 +3,7 @@
  */
 
 private import codeql.dataflow.DataFlow
+private import semmle.code.cpp.Location
 
 module Private {
   import DataFlowPrivate
@@ -13,7 +14,7 @@ module Public {
   import DataFlowUtil
 }
 
-module CppDataFlow implements InputSig {
+module CppDataFlow implements InputSig<Location> {
   import Private
   import Public
 

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll

@@ -448,7 +448,7 @@ class Node extends TIRDataFlowNode {
    * For more information, see
    * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
    */
-  predicate hasLocationInfo(
+  deprecated predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
   ) {
     this.getLocation().hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)
@@ -1331,6 +1331,7 @@ private import GetConvertedResultExpression
 
 /** Holds if `node` is an `OperandNode` that should map `node.asExpr()` to `e`. */
 predicate exprNodeShouldBeOperand(OperandNode node, Expr e, int n) {
+  not exprNodeShouldBeIndirectOperand(_, e, n) and
   exists(Instruction def |
     unique( | | getAUse(def)) = node.getOperand() and
     e = getConvertedResultExpression(def, n)
@@ -1347,6 +1348,22 @@ private predicate indirectExprNodeShouldBeIndirectOperand(
   )
 }
 
+/** Holds if `node` should be an `IndirectOperand` that maps `node.asExpr()` to `e`. */
+private predicate exprNodeShouldBeIndirectOperand(IndirectOperand node, Expr e, int n) {
+  exists(ArgumentOperand operand |
+    // When an argument (qualifier or positional) is a prvalue and the
+    // parameter (qualifier or positional) is a (const) reference, IR
+    // construction introduces a temporary `IRVariable`. The `VariableAddress`
+    // instruction has the argument as its `getConvertedResultExpression`
+    // result. However, the instruction actually represents the _address_ of
+    // the argument. So to fix this mismatch, we have the indirection of the
+    // `VariableAddressInstruction` map to the expression.
+    node.hasOperandAndIndirectionIndex(operand, 1) and
+    e = getConvertedResultExpression(operand.getDef(), n) and
+    operand.getDef().(VariableAddressInstruction).getIRVariable() instanceof IRTempVariable
+  )
+}
+
 private predicate exprNodeShouldBeIndirectOutNode(IndirectArgumentOutNode node, Expr e, int n) {
   exists(CallInstruction call |
     call.getStaticCallTarget() instanceof Constructor and
@@ -1359,6 +1376,7 @@ private predicate exprNodeShouldBeIndirectOutNode(IndirectArgumentOutNode node,
 predicate exprNodeShouldBeInstruction(Node node, Expr e, int n) {
   not exprNodeShouldBeOperand(_, e, n) and
   not exprNodeShouldBeIndirectOutNode(_, e, n) and
+  not exprNodeShouldBeIndirectOperand(_, e, n) and
   e = getConvertedResultExpression(node.asInstruction(), n)
 }
 
@@ -1391,7 +1409,8 @@ abstract private class ExprNodeBase extends Node {
 private predicate exprNodeShouldBe(Expr e, int n) {
   exprNodeShouldBeInstruction(_, e, n) or
   exprNodeShouldBeOperand(_, e, n) or
-  exprNodeShouldBeIndirectOutNode(_, e, n)
+  exprNodeShouldBeIndirectOutNode(_, e, n) or
+  exprNodeShouldBeIndirectOperand(_, e, n)
 }
 
 private class InstructionExprNode extends ExprNodeBase, InstructionNode {
@@ -1533,6 +1552,12 @@ private class IndirectArgumentOutExprNode extends ExprNodeBase, IndirectArgument
   final override Expr getConvertedExpr(int n) { exprNodeShouldBeIndirectOutNode(this, result, n) }
 }
 
+private class IndirectOperandExprNode extends ExprNodeBase instanceof IndirectOperand {
+  IndirectOperandExprNode() { exprNodeShouldBeIndirectOperand(this, _, _) }
+
+  final override Expr getConvertedExpr(int n) { exprNodeShouldBeIndirectOperand(this, result, n) }
+}
+
 /**
  * An expression, viewed as a node in a data flow graph.
  */
@@ -2276,8 +2301,8 @@ private import ContentStars
 
 /** A reference through a non-union instance field. */
 class FieldContent extends Content, TFieldContent {
-  Field f;
-  int indirectionIndex;
+  private Field f;
+  private int indirectionIndex;
 
   FieldContent() { this = TFieldContent(f, indirectionIndex) }
 
@@ -2304,9 +2329,9 @@ class FieldContent extends Content, TFieldContent {
 
 /** A reference through an instance field of a union. */
 class UnionContent extends Content, TUnionContent {
-  Union u;
-  int indirectionIndex;
-  int bytes;
+  private Union u;
+  private int indirectionIndex;
+  private int bytes;
 
   UnionContent() { this = TUnionContent(u, bytes, indirectionIndex) }
 

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/SsaInternals.qll

@@ -103,6 +103,7 @@ predicate hasRawIndirectInstruction(Instruction instr, int indirectionIndex) {
 
 cached
 private newtype TDefOrUseImpl =
+  TDefAddressImpl(BaseIRVariable v) or
   TDefImpl(BaseSourceVariableInstruction base, Operand address, int indirectionIndex) {
     isDef(_, _, address, base, _, indirectionIndex)
   } or
@@ -256,24 +257,64 @@ private predicate sourceVariableHasBaseAndIndex(SourceVariable v, BaseSourceVari
 }
 
 abstract class DefImpl extends DefOrUseImpl {
-  Operand address;
   int ind;
 
   bindingset[ind]
   DefImpl() { any() }
 
-  abstract int getIndirection();
-
-  abstract Node0Impl getValue();
-
-  abstract predicate isCertain();
-
-  Operand getAddressOperand() { result = address }
-
   override int getIndirectionIndex() { result = ind }
 
   override string toString() { result = "Def of " + this.getSourceVariable() }
 
+  abstract int getIndirection();
+
+  abstract predicate isCertain();
+
+  abstract Node0Impl getValue();
+}
+
+/** An initial definition of an `IRVariable`'s address. */
+private class DefAddressImpl extends DefImpl, TDefAddressImpl {
+  BaseIRVariable v;
+
+  DefAddressImpl() {
+    this = TDefAddressImpl(v) and
+    ind = 0
+  }
+
+  final override int getIndirection() { result = 0 }
+
+  final override predicate isCertain() { any() }
+
+  final override Node0Impl getValue() { none() }
+
+  final override predicate hasIndexInBlock(IRBlock block, int index) {
+    block = v.getIRVariable().getEnclosingIRFunction().getEntryBlock() and
+    index = 0
+  }
+
+  override Cpp::Location getLocation() { result = v.getIRVariable().getLocation() }
+
+  final override SourceVariable getSourceVariable() {
+    result.getBaseVariable() = v and
+    result.getIndirection() = 0
+  }
+
+  final override BaseSourceVariableInstruction getBase() { none() }
+}
+
+/**
+ * An SSA definition that has an associated `Operand` representing the address
+ * that is being written to.
+ */
+abstract private class OperandBasedDef extends DefImpl {
+  Operand address;
+
+  bindingset[ind]
+  OperandBasedDef() { any() }
+
+  Operand getAddressOperand() { result = address }
+
   override Cpp::Location getLocation() { result = this.getAddressOperand().getUse().getLocation() }
 
   final override predicate hasIndexInBlock(IRBlock block, int index) {
@@ -281,7 +322,7 @@ abstract class DefImpl extends DefOrUseImpl {
   }
 }
 
-private class DirectDef extends DefImpl, TDefImpl {
+private class DirectDef extends OperandBasedDef, TDefImpl {
   BaseSourceVariableInstruction base;
 
   DirectDef() { this = TDefImpl(base, address, ind) }
@@ -295,7 +336,7 @@ private class DirectDef extends DefImpl, TDefImpl {
   override predicate isCertain() { isDef(true, _, address, base, _, ind) }
 }
 
-private class IteratorDef extends DefImpl, TIteratorDef {
+private class IteratorDef extends OperandBasedDef, TIteratorDef {
   BaseSourceVariableInstruction container;
 
   IteratorDef() { this = TIteratorDef(address, container, ind) }
@@ -1178,7 +1219,7 @@ class UseOrPhi extends SsaDefOrUse {
 class Def extends DefOrUse {
   override DefImpl defOrUse;
 
-  Operand getAddressOperand() { result = defOrUse.getAddressOperand() }
+  Operand getAddressOperand() { result = defOrUse.(OperandBasedDef).getAddressOperand() }
 
   Instruction getAddress() { result = this.getAddressOperand().getDef() }
 

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/TaintTrackingImplSpecific.qll

@@ -4,7 +4,8 @@
 
 private import codeql.dataflow.TaintTracking
 private import DataFlowImplSpecific
+private import semmle.code.cpp.Location
 
-module CppTaintTracking implements InputSig<CppDataFlow> {
+module CppTaintTracking implements InputSig<Location, CppDataFlow> {
   import TaintTrackingUtil
 }

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/TaintTrackingUtil.qll

@@ -6,6 +6,7 @@ private import semmle.code.cpp.models.interfaces.SideEffect
 private import DataFlowUtil
 private import DataFlowPrivate
 private import SsaInternals as Ssa
+private import semmle.code.cpp.ir.dataflow.FlowSteps
 
 /**
  * Holds if taint propagates from `nodeFrom` to `nodeTo` in exactly one local
@@ -37,6 +38,12 @@ predicate localAdditionalTaintStep(DataFlow::Node nodeFrom, DataFlow::Node nodeT
   )
   or
   any(Ssa::Indirection ind).isAdditionalTaintStep(nodeFrom, nodeTo)
+  or
+  // object->field conflation for content that is a `TaintInheritingContent`.
+  exists(DataFlow::ContentSet f |
+    readStep(nodeFrom, f, nodeTo) and
+    f.getAReadContent() instanceof TaintInheritingContent
+  )
 }
 
 /**

cpp/ql/lib/semmle/code/cpp/ir/implementation/EdgeKind.qll

@@ -90,6 +90,15 @@ class CaseEdge extends EdgeKind, TCaseEdge {
    * Gets the largest value of the switch expression for which control will flow along this edge.
    */
   final string getMaxValue() { result = maxValue }
+
+  /**
+   * Gets the unique value of the switch expression for which control will
+   * flow along this edge, if any.
+   */
+  final string getValue() {
+    minValue = maxValue and
+    result = minValue
+  }
 }
 
 /**

cpp/ql/lib/semmle/code/cpp/ir/implementation/aliased_ssa/constant/ConstantAnalysis.qll

@@ -38,6 +38,12 @@ private int getBinaryInstructionValue(BinaryInstruction instr) {
     or
     instr instanceof DivInstruction and result = div(left, right)
     or
+    instr instanceof BitOrInstruction and result = bitOr(left, right)
+    or
+    instr instanceof BitAndInstruction and result = bitAnd(left, right)
+    or
+    instr instanceof BitXorInstruction and result = bitXor(left, right)
+    or
     instr instanceof CompareEQInstruction and result = compareEQ(left, right)
     or
     instr instanceof CompareNEInstruction and result = compareNE(left, right)

cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/constant/ConstantAnalysis.qll

@@ -38,6 +38,12 @@ private int getBinaryInstructionValue(BinaryInstruction instr) {
     or
     instr instanceof DivInstruction and result = div(left, right)
     or
+    instr instanceof BitOrInstruction and result = bitOr(left, right)
+    or
+    instr instanceof BitAndInstruction and result = bitAnd(left, right)
+    or
+    instr instanceof BitXorInstruction and result = bitXor(left, right)
+    or
     instr instanceof CompareEQInstruction and result = compareEQ(left, right)
     or
     instr instanceof CompareNEInstruction and result = compareNE(left, right)

cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/internal/TranslatedElement.qll

@@ -40,12 +40,43 @@ IRTempVariable getIRTempVariable(Locatable ast, TempVariableTag tag) {
   result.getTag() = tag
 }
 
+/** Gets an operand of `op`. */
+private Expr getAnOperand(Operation op) { result = op.getAnOperand() }
+
+/**
+ * Gets the number of nested operands of `op`. For example,
+ * `getNumberOfNestedBinaryOperands((1 + 2) + 3))` is `3`.
+ */
+private int getNumberOfNestedBinaryOperands(Operation op) { result = count(getAnOperand*(op)) }
+
+/**
+ * Holds if `op` should not be translated to a `ConstantInstruction` as part of
+ * IR generation, even if the value of `op` is constant.
+ */
+private predicate ignoreConstantValue(Operation op) {
+  op instanceof BitwiseAndExpr
+  or
+  op instanceof BitwiseOrExpr
+  or
+  op instanceof BitwiseXorExpr
+}
+
 /**
  * Holds if `expr` is a constant of a type that can be replaced directly with
  * its value in the IR. This does not include address constants as we have no
  * means to express those as QL values.
  */
-predicate isIRConstant(Expr expr) { exists(expr.getValue()) }
+predicate isIRConstant(Expr expr) {
+  exists(expr.getValue()) and
+  // We avoid constant folding certain operations since it's often useful to
+  // mark one of those as a source in dataflow, and if the operation is
+  // constant folded it's not possible to mark its operands as a source (or
+  // sink).
+  // But to avoid creating an outrageous amount of IR from very large
+  // constant expressions we fall back to constant folding if the operation
+  // has more than 50 operands (i.e., 1 + 2 + 3 + 4 + ... + 50)
+  if ignoreConstantValue(expr) then getNumberOfNestedBinaryOperands(expr) > 50 else any()
+}
 
 // Pulled out for performance. See
 // https://github.com/github/codeql-coreql-team/issues/1044.

cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/internal/TranslatedExpr.qll

@@ -2769,6 +2769,50 @@ class TranslatedTemporaryObjectExpr extends TranslatedNonConstantExpr,
   final override Instruction getResult() { result = this.getTargetAddress() }
 }
 
+/**
+ * IR translation of a `ReuseExpr`.
+ *
+ * This translation produces a copy of the glvalue instruction holding the (unconverted) result
+ * of the reused expression. In the case where the original expression was a prvalue, the
+ * result will be a copy of the glvalue operand of a `TranslatedLoad`.
+ */
+class TranslatedReuseExpr extends TranslatedNonConstantExpr {
+  override ReuseExpr expr;
+
+  override Instruction getFirstInstruction(EdgeKind kind) {
+    result = this.getInstruction(OnlyInstructionTag()) and
+    kind instanceof GotoEdge
+  }
+
+  override predicate hasInstruction(Opcode opcode, InstructionTag tag, CppType resultType) {
+    opcode instanceof Opcode::CopyValue and
+    tag instanceof OnlyInstructionTag and
+    resultType = this.getResultType()
+  }
+
+  override Instruction getResult() { result = this.getInstruction(OnlyInstructionTag()) }
+
+  override Instruction getInstructionSuccessorInternal(InstructionTag tag, EdgeKind kind) {
+    tag = OnlyInstructionTag() and
+    kind instanceof GotoEdge and
+    result = this.getParent().getChildSuccessor(this, kind)
+  }
+
+  override TranslatedElement getChildInternal(int id) { none() }
+
+  override Instruction getALastInstructionInternal() {
+    result = this.getInstruction(OnlyInstructionTag())
+  }
+
+  override Instruction getInstructionRegisterOperand(InstructionTag tag, OperandTag operandTag) {
+    tag = OnlyInstructionTag() and
+    operandTag instanceof UnaryOperandTag and
+    if getTranslatedExpr(expr.getReusedExpr()) instanceof TranslatedLoad
+    then result = getTranslatedExpr(expr.getReusedExpr()).(TranslatedLoad).getOperand().getResult()
+    else result = getTranslatedExpr(expr.getReusedExpr()).getResult()
+  }
+}
+
 /**
  * IR translation of a `throw` expression.
  */

cpp/ql/lib/semmle/code/cpp/ir/implementation/unaliased_ssa/constant/ConstantAnalysis.qll

@@ -38,6 +38,12 @@ private int getBinaryInstructionValue(BinaryInstruction instr) {
     or
     instr instanceof DivInstruction and result = div(left, right)
     or
+    instr instanceof BitOrInstruction and result = bitOr(left, right)
+    or
+    instr instanceof BitAndInstruction and result = bitAnd(left, right)
+    or
+    instr instanceof BitXorInstruction and result = bitXor(left, right)
+    or
     instr instanceof CompareEQInstruction and result = compareEQ(left, right)
     or
     instr instanceof CompareNEInstruction and result = compareNE(left, right)

cpp/ql/lib/semmle/code/cpp/ir/internal/IntegerPartial.qll

@@ -89,6 +89,18 @@ int compareLE(int a, int b) { if a <= b then result = 1 else result = 0 }
 bindingset[a, b]
 int compareGE(int a, int b) { if a >= b then result = 1 else result = 0 }
 
+/** Returns `a | b`. */
+bindingset[a, b]
+int bitOr(int a, int b) { result = a.bitOr(b) }
+
+/** Returns `a & b`. */
+bindingset[a, b]
+int bitAnd(int a, int b) { result = a.bitAnd(b) }
+
+/** Returns `a ^ b`. */
+bindingset[a, b]
+int bitXor(int a, int b) { result = a.bitXor(b) }
+
 /**
  * Returns `-a`. If the negation would overflow, there is no result.
  */

cpp/ql/lib/semmle/code/cpp/models/implementations/Allocation.qll

@@ -36,7 +36,9 @@ private class MallocAllocationFunction extends AllocationFunction {
         "CRYPTO_malloc", // CRYPTO_malloc(size_t num, const char *file, int line)
         "CRYPTO_zalloc", // CRYPTO_zalloc(size_t num, const char *file, int line)
         "CRYPTO_secure_malloc", // CRYPTO_secure_malloc(size_t num, const char *file, int line)
-        "CRYPTO_secure_zalloc" // CRYPTO_secure_zalloc(size_t num, const char *file, int line)
+        "CRYPTO_secure_zalloc", // CRYPTO_secure_zalloc(size_t num, const char *file, int line)
+        "g_malloc", // g_malloc (n_bytes);
+        "g_try_malloc" // g_try_malloc(n_bytes);
       ]) and
     sizeArg = 0
     or
@@ -139,7 +141,9 @@ private class ReallocAllocationFunction extends AllocationFunction, TaintFunctio
         // --- Windows COM allocation
         "CoTaskMemRealloc", // CoTaskMemRealloc(ptr, size)
         // --- OpenSSL memory allocation
-        "CRYPTO_realloc" // CRYPTO_realloc(void *addr, size_t num, const char *file, int line)
+        "CRYPTO_realloc", // CRYPTO_realloc(void *addr, size_t num, const char *file, int line)
+        "g_realloc", // g_realloc(mem, n_bytes);
+        "g_try_realloc" // g_try_realloc(mem, n_bytes);
       ]) and
     sizeArg = 1 and
     reallocArg = 0

cpp/ql/lib/semmle/code/cpp/models/implementations/Deallocation.qll

@@ -20,8 +20,10 @@ private class StandardDeallocationFunction extends DeallocationFunction {
     freedArg = 0
     or
     this.hasGlobalName([
-        // --- OpenSSL memory allocation
-        "CRYPTO_free", "CRYPTO_secure_free"
+        // --- OpenSSL memory deallocation
+        "CRYPTO_free", "CRYPTO_secure_free",
+        // --- glib memory deallocation
+        "g_free"
       ]) and
     freedArg = 0
     or

cpp/ql/lib/semmle/code/cpp/models/implementations/Iterator.qll

@@ -9,6 +9,8 @@ import cpp
 import semmle.code.cpp.models.interfaces.Taint
 import semmle.code.cpp.models.interfaces.DataFlow
 import semmle.code.cpp.models.interfaces.Iterator
+import semmle.code.cpp.models.interfaces.Alias
+import semmle.code.cpp.models.interfaces.SideEffect
 
 /**
  * An instantiation of the `std::iterator_traits` template.
@@ -438,7 +440,7 @@ private class IteratorAssignmentMemberOperatorModel extends IteratorAssignmentMe
  * A `begin` or `end` member function, or a related member function, that
  * returns an iterator.
  */
-private class BeginOrEndFunction extends MemberFunction, TaintFunction, GetIteratorFunction {
+class BeginOrEndFunction extends MemberFunction {
   BeginOrEndFunction() {
     this.hasName([
         "begin", "cbegin", "rbegin", "crbegin", "end", "cend", "rend", "crend", "before_begin",
@@ -446,7 +448,11 @@ private class BeginOrEndFunction extends MemberFunction, TaintFunction, GetItera
       ]) and
     this.getType().getUnspecifiedType() instanceof Iterator
   }
+}
 
+private class BeginOrEndFunctionModels extends BeginOrEndFunction, TaintFunction,
+  GetIteratorFunction, AliasFunction, SideEffectFunction
+{
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     input.isQualifierObject() and
     output.isReturnValue()
@@ -456,6 +462,22 @@ private class BeginOrEndFunction extends MemberFunction, TaintFunction, GetItera
     input.isQualifierObject() and
     output.isReturnValue()
   }
+
+  override predicate parameterNeverEscapes(int index) { index = -1 }
+
+  override predicate parameterEscapesOnlyViaReturn(int index) { none() }
+
+  override predicate hasOnlySpecificReadSideEffects() { any() }
+
+  override predicate hasOnlySpecificWriteSideEffects() { any() }
+
+  override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
+    none()
+  }
+
+  override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
+    i = -1 and buffer = false
+  }
 }
 
 /**

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

@@ -253,13 +253,15 @@ private class StdSequenceContainerAssign extends TaintFunction {
 /**
  * The standard container functions `at` and `operator[]`.
  */
-private class StdSequenceContainerAt extends TaintFunction {
+class StdSequenceContainerAt extends MemberFunction {
   StdSequenceContainerAt() {
     this.getClassAndName(["at", "operator[]"]) instanceof Array or
     this.getClassAndName(["at", "operator[]"]) instanceof Deque or
     this.getClassAndName(["at", "operator[]"]) instanceof Vector
   }
+}
 
+private class StdSequenceContainerAtModel extends StdSequenceContainerAt, TaintFunction {
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     // flow from qualifier to referenced return value
     input.isQualifierObject() and

cpp/ql/lib/semmle/code/cpp/models/implementations/StdMap.qll

@@ -129,9 +129,11 @@ private class StdMapMerge extends TaintFunction {
 /**
  * The standard map functions `at` and `operator[]`.
  */
-private class StdMapAt extends TaintFunction {
+class StdMapAt extends MemberFunction {
   StdMapAt() { this.getClassAndName(["at", "operator[]"]) instanceof MapOrUnorderedMap }
+}
 
+private class StdMapAtModels extends StdMapAt, TaintFunction {
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     // flow from qualifier to referenced return value
     input.isQualifierObject() and

cpp/ql/lib/semmlecode.cpp.dbscheme

@@ -1513,6 +1513,12 @@ exprs(
     int location: @location_expr ref
 );
 
+expr_reuse(
+    int reuse: @expr ref,
+    int original: @expr ref,
+    int value_category: int ref
+)
+
 /*
   case @value.category of
     1 = prval
@@ -1741,6 +1747,7 @@ case @expr.kind of
 | 360 = @isunsigned
 | 361 = @isvoid
 | 362 = @isvolatile
+| 363 = @reuseexpr
 ;
 
 @var_args_expr = @vastartexpr

cpp/ql/lib/upgrades/298438feb146335af824002589cd6d4e96e5dbf9/upgrade.properties

@@ -0,0 +1,2 @@
+description: Introduce re-use expressions
+compatibility: backwards

cpp/ql/lib/upgrades/aa7ff0ab32cd4674f6ab731d32fea64116997b05/expr_reuse.ql

@@ -0,0 +1,7 @@
+class Expr extends @expr {
+  string toString() { none() }
+}
+
+from Expr reuse, Expr original, int value_category
+where expr_reuse(reuse, original) and expr_types(original, _, value_category)
+select reuse, original, value_category

cpp/ql/lib/upgrades/aa7ff0ab32cd4674f6ab731d32fea64116997b05/upgrade.properties

@@ -0,0 +1,3 @@
+description: Add value category to expr_reuse table
+compatibility: full
+expr_reuse.rel: run expr_reuse.qlo

cpp/ql/src/CHANGELOG.md

@@ -1,3 +1,34 @@
+## 0.9.9
+
+### New Queries
+
+* Added a new query, `cpp/type-confusion`, to detect casts to invalid types.
+
+### Query Metadata Changes
+
+* `@precision medium` metadata was added to the `cpp/boost/tls-settings-misconfiguration` and `cpp/boost/use-of-deprecated-hardcoded-security-protocol` queries, and these queries are now included in the security-extended suite. The `@name` metadata of these queries were also updated.
+
+### Minor Analysis Improvements
+
+* The "Missing return-value check for a 'scanf'-like function" query (`cpp/missing-check-scanf`) has been converted to a `path-problem` query.
+* The "Potentially uninitialized local variable" query (`cpp/uninitialized-local`) has been converted to a `path-problem` query.
+* Added models for `GLib` allocation and deallocation functions.
+
+## 0.9.8
+
+No user-facing changes.
+
+## 0.9.7
+
+No user-facing changes.
+
+## 0.9.6
+
+### Minor Analysis Improvements
+
+* The "non-constant format string" query (`cpp/non-constant-format`) has been converted to a `path-problem` query.
+* The new C/C++ dataflow and taint-tracking libraries (`semmle.code.cpp.dataflow.new.DataFlow` and `semmle.code.cpp.dataflow.new.TaintTracking`) now implicitly assume that dataflow and taint modelled via `DataFlowFunction` and `TaintFunction` always fully overwrite their buffers and thus act as flow barriers. As a result, many dataflow and taint-tracking queries now produce fewer false positives. To remove this assumption and go back to the previous behavior for a given model, one can override the new `isPartialWrite` predicate.
+
 ## 0.9.5
 
 ### Minor Analysis Improvements

cpp/ql/src/Critical/MissingCheckScanf.ql

@@ -2,7 +2,7 @@
  * @name Missing return-value check for a 'scanf'-like function
  * @description Failing to check that a call to 'scanf' actually writes to an
  *              output variable can lead to unexpected behavior at reading time.
- * @kind problem
+ * @kind path-problem
  * @problem.severity warning
  * @security-severity 7.5
  * @precision medium
@@ -18,16 +18,9 @@ import semmle.code.cpp.commons.Scanf
 import semmle.code.cpp.controlflow.Guards
 import semmle.code.cpp.dataflow.new.DataFlow::DataFlow
 import semmle.code.cpp.ir.IR
-import semmle.code.cpp.ir.ValueNumbering
+import semmle.code.cpp.valuenumbering.GlobalValueNumbering
 import ScanfChecks
-
-/** Holds if `n` reaches an argument  to a call to a `scanf`-like function. */
-pragma[nomagic]
-predicate revFlow0(Node n) {
-  isSink(_, _, n, _)
-  or
-  exists(Node succ | revFlow0(succ) | localFlowStep(n, succ))
-}
+import ScanfToUseFlow::PathGraph
 
 /**
  * Holds if `n` represents an uninitialized stack-allocated variable, or a
@@ -38,30 +31,45 @@ predicate isUninitialized(Node n) {
   n.asIndirectExpr(1) instanceof AllocationExpr
 }
 
-pragma[nomagic]
-predicate fwdFlow0(Node n) {
-  revFlow0(n) and
-  (
-    isUninitialized(n)
-    or
-    exists(Node prev |
-      fwdFlow0(prev) and
-      localFlowStep(prev, n)
-    )
-  )
-}
-
 predicate isSink(ScanfFunctionCall call, int index, Node n, Expr input) {
   input = call.getOutputArgument(index) and
   n.asIndirectExpr() = input
 }
 
+/**
+ * A configuration to track a uninitialized data flowing to a `scanf`-like
+ * output parameter position.
+ *
+ * This is meant to be a simple flow to rule out cases like:
+ * ```
+ * int x = 0;
+ * scanf(..., &x);
+ * use(x);
+ * ```
+ * since `x` is already initialized it's not a security concern that `x` is
+ * used without checking the return value of `scanf`.
+ *
+ * Since this flow is meant to be simple, we disable field flow and require the
+ * source and the sink to be in the same callable.
+ */
+module UninitializedToScanfConfig implements ConfigSig {
+  predicate isSource(Node source) { isUninitialized(source) }
+
+  predicate isSink(Node sink) { isSink(_, _, sink, _) }
+
+  FlowFeature getAFeature() { result instanceof FeatureEqualSourceSinkCallContext }
+
+  int accessPathLimit() { result = 0 }
+}
+
+module UninitializedToScanfFlow = Global<UninitializedToScanfConfig>;
+
 /**
  * Holds if `call` is a `scanf`-like call and `output` is the `index`'th
  * argument that has not been previously initialized.
  */
 predicate isRelevantScanfCall(ScanfFunctionCall call, int index, Expr output) {
-  exists(Node n | fwdFlow0(n) and isSink(call, index, n, output)) and
+  exists(Node n | UninitializedToScanfFlow::flowTo(n) and isSink(call, index, n, output)) and
   // Exclude results from incorrectky checked scanf query
   not incorrectlyCheckedScanf(call)
 }
@@ -77,31 +85,6 @@ predicate isSource(ScanfFunctionCall call, int index, Node n, Expr output) {
   n.asDefiningArgument() = output
 }
 
-/**
- * Holds if `n` is reachable from an output argument of a relevant call to
- * a `scanf`-like function.
- */
-pragma[nomagic]
-predicate fwdFlow(Node n) {
-  isSource(_, _, n, _)
-  or
-  exists(Node prev |
-    fwdFlow(prev) and
-    localFlowStep(prev, n) and
-    not isSanitizerOut(prev)
-  )
-}
-
-/** Holds if `n` should not have outgoing flow. */
-predicate isSanitizerOut(Node n) {
-  // We disable flow out of sinks to reduce result duplication
-  isSink(n, _)
-  or
-  // If the node is being passed to a function it may be
-  // modified, and thus it's safe to later read the value.
-  exists(n.asIndirectArgument())
-}
-
 /**
  * Holds if `n` is a node such that `n.asExpr() = e` and `e` is not an
  * argument of a deallocation expression.
@@ -112,40 +95,37 @@ predicate isSink(Node n, Expr e) {
 }
 
 /**
- * Holds if `n` is part of a path from a call to a `scanf`-like function
- * to a use of the written variable.
+ * A configuration to track flow from the output argument of a call to a
+ * `scanf`-like function, and to a use of the defined variable.
  */
-pragma[nomagic]
-predicate revFlow(Node n) {
-  fwdFlow(n) and
-  (
+module ScanfToUseConfig implements ConfigSig {
+  predicate isSource(Node source) { isSource(_, _, source, _) }
+
+  predicate isSink(Node sink) { isSink(sink, _) }
+
+  predicate isBarrierOut(Node n) {
+    // We disable flow out of sinks to reduce result duplication
     isSink(n, _)
     or
-    exists(Node succ |
-      revFlow(succ) and
-      localFlowStep(n, succ) and
-      not isSanitizerOut(n)
-    )
-  )
+    // If the node is being passed to a function it may be
+    // modified, and thus it's safe to later read the value.
+    exists(n.asIndirectArgument())
+  }
 }
 
-/** A local flow step, restricted to relevant dataflow nodes. */
-private predicate step(Node n1, Node n2) {
-  revFlow(n1) and
-  revFlow(n2) and
-  localFlowStep(n1, n2)
-}
-
-predicate hasFlow(Node n1, Node n2) = fastTC(step/2)(n1, n2)
+module ScanfToUseFlow = Global<ScanfToUseConfig>;
 
 /**
  * Holds if `source` is the `index`'th argument to the `scanf`-like call `call`, and `sink` is
  * a dataflow node that represents the expression `e`.
  */
-predicate hasFlow(Node source, ScanfFunctionCall call, int index, Node sink, Expr e) {
-  isSource(call, index, source, _) and
-  hasFlow(source, sink) and
-  isSink(sink, e)
+predicate flowPath(
+  ScanfToUseFlow::PathNode source, ScanfFunctionCall call, int index, ScanfToUseFlow::PathNode sink,
+  Expr e
+) {
+  isSource(call, index, source.getNode(), _) and
+  ScanfToUseFlow::flowPath(source, sink) and
+  isSink(sink.getNode(), e)
 }
 
 /**
@@ -167,39 +147,33 @@ int getMinimumGuardConstant(ScanfFunctionCall call, int index) {
  * Holds the access to `e` isn't guarded by a check that ensures that `call` returned
  * at least `minGuard`.
  */
-predicate hasNonGuardedAccess(ScanfFunctionCall call, Expr e, int minGuard) {
+predicate hasNonGuardedAccess(
+  ScanfToUseFlow::PathNode source, ScanfFunctionCall call, ScanfToUseFlow::PathNode sink, Expr e,
+  int minGuard
+) {
   exists(int index |
-    hasFlow(_, call, index, _, e) and
+    flowPath(source, call, index, sink, e) and
     minGuard = getMinimumGuardConstant(call, index)
   |
-    not exists(int value |
-      e.getBasicBlock() = blockGuardedBy(value, "==", call) and minGuard <= value
+    not exists(GuardCondition guard |
+      // call == k and k >= minGuard so call >= minGuard
+      guard
+          .ensuresEq(globalValueNumber(call).getAnExpr(), any(int k | minGuard <= k),
+            e.getBasicBlock(), true)
       or
-      e.getBasicBlock() = blockGuardedBy(value, "<", call) and minGuard - 1 <= value
-      or
-      e.getBasicBlock() = blockGuardedBy(value, "<=", call) and minGuard <= value
+      // call >= k and k >= minGuard so call >= minGuard
+      guard
+          .ensuresLt(globalValueNumber(call).getAnExpr(), any(int k | minGuard <= k),
+            e.getBasicBlock(), false)
     )
   )
 }
 
-/** Returns a block guarded by the assertion of `value op call` */
-BasicBlock blockGuardedBy(int value, string op, ScanfFunctionCall call) {
-  exists(GuardCondition g, Expr left, Expr right |
-    right = g.getAChild() and
-    value = left.getValue().toInt() and
-    localExprFlow(call, right)
-  |
-    g.ensuresEq(left, right, 0, result, true) and op = "=="
-    or
-    g.ensuresLt(left, right, 0, result, true) and op = "<"
-    or
-    g.ensuresLt(left, right, 1, result, true) and op = "<="
-  )
-}
-
-from ScanfFunctionCall call, Expr e, int minGuard
-where hasNonGuardedAccess(call, e, minGuard)
-select e,
+from
+  ScanfToUseFlow::PathNode source, ScanfToUseFlow::PathNode sink, ScanfFunctionCall call, Expr e,
+  int minGuard
+where hasNonGuardedAccess(source, call, sink, e, minGuard)
+select e, source, sink,
   "This variable is read, but may not have been written. " +
     "It should be guarded by a check that the $@ returns at least " + minGuard + ".", call,
   call.toString()

cpp/ql/src/Critical/ScanfChecks.qll

@@ -3,15 +3,11 @@ private import semmle.code.cpp.commons.Scanf
 private import semmle.code.cpp.controlflow.IRGuards
 private import semmle.code.cpp.ir.ValueNumbering
 
-private ConstantInstruction getZeroInstruction() { result.getValue() = "0" }
-
-private Operand zero() { result.getDef() = getZeroInstruction() }
-
 private predicate exprInBooleanContext(Expr e) {
   exists(IRGuardCondition gc |
     exists(Instruction i |
       i.getUnconvertedResultExpression() = e and
-      gc.comparesEq(valueNumber(i).getAUse(), zero(), 0, _, _)
+      gc.comparesEq(valueNumber(i).getAUse(), 0, _, _)
     )
     or
     gc.getUnconvertedResultExpression() = e
@@ -36,10 +32,6 @@ private string getEofValue() {
   )
 }
 
-private ConstantInstruction getEofInstruction() { result.getValue() = getEofValue() }
-
-private Operand eof() { result.getDef() = getEofInstruction() }
-
 /**
  * Holds if the value of `call` has been checked to not equal `EOF`.
  */
@@ -47,10 +39,10 @@ private predicate checkedForEof(ScanfFunctionCall call) {
   exists(IRGuardCondition gc |
     exists(Instruction i | i.getUnconvertedResultExpression() = call |
       // call == EOF
-      gc.comparesEq(valueNumber(i).getAUse(), eof(), 0, _, _)
+      gc.comparesEq(valueNumber(i).getAUse(), getEofValue().toInt(), _, _)
       or
       // call < 0 (EOF is guaranteed to be negative)
-      gc.comparesLt(valueNumber(i).getAUse(), zero(), 0, true, _)
+      gc.comparesLt(valueNumber(i).getAUse(), 0, true, _)
     )
   )
 }

cpp/ql/src/Likely Bugs/Format/NonConstantFormat.ql

@@ -37,6 +37,37 @@ class UncalledFunction extends Function {
   }
 }
 
+/** The `unsigned short` type. */
+class UnsignedShort extends ShortType {
+  UnsignedShort() { this.isUnsigned() }
+}
+
+/**
+ * Holds if `t` cannot refer to a string. That is, it's a built-in
+ * or arithmetic type that is not a "`char` like" type.
+ */
+predicate cannotContainString(Type t) {
+  exists(Type unspecified |
+    unspecified = t.getUnspecifiedType() and
+    not unspecified instanceof UnknownType and
+    not unspecified instanceof CharType and
+    not unspecified instanceof WideCharType and
+    not unspecified instanceof Char8Type and
+    not unspecified instanceof Char16Type and
+    not unspecified instanceof Char32Type and
+    // C often defines `wchar_t` as `unsigned short`
+    not unspecified instanceof UnsignedShort
+  |
+    unspecified instanceof ArithmeticType or
+    unspecified instanceof BuiltInType
+  )
+}
+
+predicate dataFlowOrTaintFlowFunction(Function func, FunctionOutput output) {
+  func.(DataFlowFunction).hasDataFlow(_, output) or
+  func.(TaintFunction).hasTaintFlow(_, output)
+}
+
 /**
  * Holds if `node` is a non-constant source of data flow for non-const format string detection.
  * This is defined as either:
@@ -69,7 +100,9 @@ predicate isNonConst(DataFlow::Node node) {
   // Parameters of uncalled functions that aren't const
   exists(UncalledFunction f, Parameter p |
     f.getAParameter() = p and
-    p = node.asParameter() and
+    // We pick the indirection of the parameter since this query is focused
+    // on strings.
+    p = node.asParameter(1) and
     // Ignore main's argv parameter as it is already considered a `FlowSource`
     // not ignoring it will result in path redundancies
     (f.getName() = "main" implies p != f.getParameter(1))
@@ -82,30 +115,27 @@ predicate isNonConst(DataFlow::Node node) {
   //       are considered as possible non-const sources
   // The function's output must also not be const to be considered a non-const source
   exists(Function func, CallInstruction call |
-    // NOTE: could use `Call` getAnArgument() instead of `CallInstruction` but requires two
-    // variables representing the same call in ordoer to use `callOutput` below.
-    exists(Expr arg |
-      call.getPositionalArgumentOperand(_).getDef().getUnconvertedResultExpression() = arg and
-      arg = node.asDefiningArgument()
-    )
-    or
-    call.getUnconvertedResultExpression() = node.asIndirectExpr()
+    not func.hasDefinition() and
+    func = call.getStaticCallTarget()
   |
-    func = call.getStaticCallTarget() and
+    // Case 1: It's a known dataflow or taintflow function with flow to the return value
+    call.getUnconvertedResultExpression() = node.asIndirectExpr() and
     not exists(FunctionOutput output |
-      // NOTE: we must include dataflow and taintflow. e.g., including only dataflow we will find sprintf
-      // variant function's output are now possible non-const sources
-      pragma[only_bind_out](func).(DataFlowFunction).hasDataFlow(_, output) or
-      pragma[only_bind_out](func).(TaintFunction).hasTaintFlow(_, output)
-    |
+      dataFlowOrTaintFlowFunction(func, output) and
+      output.isReturnValueDeref(_) and
       node = callOutput(call, output)
     )
-  ) and
-  not exists(Call c |
-    c.getTarget().hasDefinition() and
-    if node instanceof DataFlow::DefinitionByReferenceNode
-    then c.getAnArgument() = node.asDefiningArgument()
-    else c = [node.asExpr(), node.asIndirectExpr()]
+    or
+    // Case 2: It's a known dataflow or taintflow function with flow to an output parameter
+    exists(int i |
+      call.getPositionalArgumentOperand(i).getDef().getUnconvertedResultExpression() =
+        node.asDefiningArgument() and
+      not exists(FunctionOutput output |
+        dataFlowOrTaintFlowFunction(func, output) and
+        output.isParameterDeref(i, _) and
+        node = callOutput(call, output)
+      )
+    )
   )
 }
 
@@ -114,18 +144,29 @@ predicate isNonConst(DataFlow::Node node) {
  * `FormattingFunctionCall`.
  */
 predicate isSinkImpl(DataFlow::Node sink, Expr formatString) {
-  [sink.asExpr(), sink.asIndirectExpr()] = formatString and
+  sink.asIndirectExpr() = formatString and
   exists(FormattingFunctionCall fc | formatString = fc.getArgument(fc.getFormatParameterIndex()))
 }
 
 module NonConstFlowConfig implements DataFlow::ConfigSig {
-  predicate isSource(DataFlow::Node source) { isNonConst(source) }
+  predicate isSource(DataFlow::Node source) {
+    exists(Type t |
+      isNonConst(source) and
+      t = source.getType() and
+      not cannotContainString(t)
+    )
+  }
 
   predicate isSink(DataFlow::Node sink) { isSinkImpl(sink, _) }
 
   predicate isBarrier(DataFlow::Node node) {
     // Ignore tracing non-const through array indices
-    exists(ArrayExpr a | a.getArrayOffset() = node.asExpr())
+    exists(ArrayExpr a | a.getArrayOffset() = node.asIndirectExpr())
+    or
+    exists(Type t |
+      t = node.getType() and
+      cannotContainString(t)
+    )
   }
 }
 

cpp/ql/src/Likely Bugs/Memory Management/UninitializedLocal.ql

@@ -2,7 +2,7 @@
  * @name Potentially uninitialized local variable
  * @description Reading from a local variable that has not been assigned to
  *              will typically yield garbage.
- * @kind problem
+ * @kind path-problem
  * @id cpp/uninitialized-local
  * @problem.severity warning
  * @security-severity 7.8
@@ -15,6 +15,7 @@
 import cpp
 import semmle.code.cpp.ir.IR
 import semmle.code.cpp.ir.dataflow.MustFlow
+import PathGraph
 
 /**
  * Auxiliary predicate: Types that don't require initialization
@@ -89,4 +90,4 @@ where
   conf.hasFlowPath(source, sink) and
   isSinkImpl(sink.getInstruction(), va) and
   v = va.getTarget()
-select va, "The variable $@ may not be initialized at this access.", v, v.getName()
+select va, source, sink, "The variable $@ may not be initialized at this access.", v, v.getName()

cpp/ql/src/Likely Bugs/Protocols/TlsSettingsMisconfiguration.ql

@@ -1,8 +1,9 @@
 /**
- * @name Boost_asio TLS Settings Misconfiguration
+ * @name boost::asio TLS settings misconfiguration
  * @description Using the TLS or SSLv23 protocol from the boost::asio library, but not disabling deprecated protocols, or disabling minimum-recommended protocols.
  * @kind problem
  * @problem.severity error
+ * @precision medium
  * @security-severity 7.5
  * @id cpp/boost/tls-settings-misconfiguration
  * @tags security
@@ -12,34 +13,41 @@
 import cpp
 import semmle.code.cpp.security.boostorg.asio.protocols
 
-module ExistsAnyFlowConfig implements DataFlow::ConfigSig {
-  predicate isSource(DataFlow::Node source) {
-    exists(BoostorgAsio::SslContextClass c | c.getAContructorCall() = source.asExpr())
-  }
+predicate isSourceImpl(DataFlow::Node source, ConstructorCall cc) {
+  exists(BoostorgAsio::SslContextClass c | c.getAContructorCall() = cc and cc = source.asExpr())
+}
 
-  predicate isSink(DataFlow::Node sink) {
-    exists(BoostorgAsio::SslSetOptionsFunction f, FunctionCall fcSetOptions |
-      f.getACallToThisFunction() = fcSetOptions and
-      fcSetOptions.getQualifier() = sink.asExpr()
-    )
-  }
+predicate isSinkImpl(DataFlow::Node sink, FunctionCall fcSetOptions) {
+  exists(BoostorgAsio::SslSetOptionsFunction f |
+    f.getACallToThisFunction() = fcSetOptions and
+    fcSetOptions.getQualifier() = sink.asIndirectExpr()
+  )
+}
+
+module ExistsAnyFlowConfig implements DataFlow::ConfigSig {
+  predicate isSource(DataFlow::Node source) { isSourceImpl(source, _) }
+
+  predicate isSink(DataFlow::Node sink) { isSinkImpl(sink, _) }
 }
 
 module ExistsAnyFlow = DataFlow::Global<ExistsAnyFlowConfig>;
 
 bindingset[flag]
 predicate isOptionSet(ConstructorCall cc, int flag, FunctionCall fcSetOptions) {
-  exists(VariableAccess contextSetOptions |
-    ExistsAnyFlow::flow(DataFlow::exprNode(cc), DataFlow::exprNode(contextSetOptions)) and
-    exists(BoostorgAsio::SslSetOptionsFunction f | f.getACallToThisFunction() = fcSetOptions |
-      contextSetOptions = fcSetOptions.getQualifier() and
-      forall(Expr optionArgument, Expr optionArgumentSource |
-        optionArgument = fcSetOptions.getArgument(0) and
-        BoostorgAsio::SslOptionFlow::flow(DataFlow::exprNode(optionArgumentSource),
-          DataFlow::exprNode(optionArgument))
-      |
-        optionArgument.getValue().toInt().bitShiftRight(16).bitAnd(flag) = flag
-      )
+  exists(
+    VariableAccess contextSetOptions, BoostorgAsio::SslSetOptionsFunction f, DataFlow::Node source,
+    DataFlow::Node sink
+  |
+    isSourceImpl(source, cc) and
+    isSinkImpl(sink, fcSetOptions) and
+    ExistsAnyFlow::flow(source, sink) and
+    f.getACallToThisFunction() = fcSetOptions and
+    contextSetOptions = fcSetOptions.getQualifier() and
+    forex(Expr optionArgument |
+      optionArgument = fcSetOptions.getArgument(0) and
+      BoostorgAsio::SslOptionFlow::flowTo(DataFlow::exprNode(optionArgument))
+    |
+      optionArgument.getValue().toInt().bitShiftRight(16).bitAnd(flag) = flag
     )
   )
 }

cpp/ql/src/Likely Bugs/Protocols/UseOfDeprecatedHardcodedProtocol.ql

@@ -1,8 +1,9 @@
 /**
- * @name boost::asio Use of deprecated hardcoded Protocol
+ * @name boost::asio use of deprecated hardcoded protocol
  * @description Using a deprecated hard-coded protocol using the boost::asio library.
  * @kind problem
  * @problem.severity error
+ * @precision medium
  * @security-severity 7.5
  * @id cpp/boost/use-of-deprecated-hardcoded-security-protocol
  * @tags security

cpp/ql/src/Security/CWE/CWE-843/TypeConfusion.qhelp

@@ -0,0 +1,50 @@
+<!DOCTYPE qhelp PUBLIC "-//Semmle//qhelp//EN" "qhelp.dtd">
+<qhelp>
+
+<overview>
+<p>
+Certain casts in C and C++ place no restrictions on the target type. For
+example, C style casts such as <code>(MyClass*)p</code> allows the programmer
+to cast any pointer <code>p</code> to an expression of type <code>MyClass*</code>.
+If the runtime type of <code>p</code> turns out to be a type that's incompatible
+with <code>MyClass</code>, this results in undefined behavior.
+</p>
+</overview>
+
+<recommendation>
+<p>
+If possible, use <code>dynamic_cast</code> to safely cast between polymorphic types.
+If <code>dynamic_cast</code> is not an option, use <code>static_cast</code> to restrict
+the kinds of conversions that the compiler is allowed to perform. If C++ style casts is
+not an option, carefully check that all casts are safe.
+</p>
+</recommendation>
+
+<example>
+<p>
+Consider the following class hierachy where we define a base class <code>Shape</code> and two
+derived classes <code>Circle</code> and <code>Square</code> that are mutually incompatible:
+</p>
+<sample src="TypeConfusionCommon.cpp"/>
+
+<p>
+The following code demonstrates a type confusion vulnerability where the programmer
+assumes that the runtime type of <code>p</code> is always a <code>Square</code>.
+However, if <code>p</code> is a <code>Circle</code>, the cast will result in undefined behavior.
+</p>
+<sample src="TypeConfusionBad.cpp"/>
+
+<p>
+The following code fixes the vulnerability by using <code>dynamic_cast</code> to
+safely cast between polymorphic types. If the cast fails, <code>dynamic_cast</code>
+returns a null pointer, which can be checked for and handled appropriately.
+</p>
+<sample src="TypeConfusionGood.cpp"/>
+</example>
+
+<references>
+<li>
+Microsoft Learn: <a href="https://learn.microsoft.com/en-us/cpp/cpp/type-conversions-and-type-safety-modern-cpp">Type conversions and type safety</a>.
+</li>
+</references>
+</qhelp>

cpp/ql/src/Security/CWE/CWE-843/TypeConfusion.ql

@@ -0,0 +1,263 @@
+/**
+ * @name Type confusion
+ * @description Casting a value to an incompatible type can lead to undefined behavior.
+ * @kind path-problem
+ * @problem.severity warning
+ * @security-severity 9.3
+ * @precision medium
+ * @id cpp/type-confusion
+ * @tags security
+ *       external/cwe/cwe-843
+ */
+
+import cpp
+import semmle.code.cpp.dataflow.new.DataFlow
+import Flow::PathGraph
+
+/**
+ * Holds if `f` is a field located at byte offset `offset` in `c`.
+ *
+ * Note that predicate is recursive, so that given the following:
+ * ```cpp
+ * struct S1 {
+ *   int a;
+ *   void* b;
+ * };
+ *
+ * struct S2 {
+ *   S1 s1;
+ *   char c;
+ * };
+ * ```
+ * both `hasAFieldWithOffset(S2, s1, 0)` and `hasAFieldWithOffset(S2, a, 0)`
+ * holds.
+ */
+predicate hasAFieldWithOffset(Class c, Field f, int offset) {
+  // Base case: `f` is a field in `c`.
+  f = c.getAField() and
+  offset = f.getByteOffset() and
+  not f.getUnspecifiedType().(Class).hasDefinition()
+  or
+  // Otherwise, we find the struct that is a field of `c` which then has
+  // the field `f` as a member.
+  exists(Field g |
+    g = c.getAField() and
+    // Find the field with the largest offset that's less than or equal to
+    // offset. That's the struct we need to search recursively.
+    g =
+      max(Field cand, int candOffset |
+        cand = c.getAField() and
+        candOffset = cand.getByteOffset() and
+        offset >= candOffset
+      |
+        cand order by candOffset
+      ) and
+    hasAFieldWithOffset(g.getUnspecifiedType(), f, offset - g.getByteOffset())
+  )
+}
+
+/** Holds if `f` is the last field of its declaring class. */
+predicate lastField(Field f) {
+  exists(Class c | c = f.getDeclaringType() |
+    f =
+      max(Field cand, int byteOffset |
+        cand.getDeclaringType() = c and byteOffset = f.getByteOffset()
+      |
+        cand order by byteOffset
+      )
+  )
+}
+
+/**
+ * Holds if there exists a field in `c2` at offset `offset` that's compatible
+ * with `f1`.
+ */
+bindingset[f1, offset, c2]
+pragma[inline_late]
+predicate hasCompatibleFieldAtOffset(Field f1, int offset, Class c2) {
+  exists(Field f2 | hasAFieldWithOffset(c2, f2, offset) |
+    // Let's not deal with bit-fields for now.
+    f2 instanceof BitField
+    or
+    f1.getUnspecifiedType().getSize() = f2.getUnspecifiedType().getSize()
+    or
+    lastField(f1) and
+    f1.getUnspecifiedType().getSize() <= f2.getUnspecifiedType().getSize()
+  )
+}
+
+/**
+ * Holds if `c1` is a prefix of `c2`.
+ */
+bindingset[c1, c2]
+pragma[inline_late]
+predicate prefix(Class c1, Class c2) {
+  not c1.isPolymorphic() and
+  not c2.isPolymorphic() and
+  if c1 instanceof Union
+  then
+    // If it's a union we just verify that one of it's variants is compatible with the other class
+    exists(Field f1, int offset |
+      // Let's not deal with bit-fields for now.
+      not f1 instanceof BitField and
+      hasAFieldWithOffset(c1, f1, offset)
+    |
+      hasCompatibleFieldAtOffset(f1, offset, c2)
+    )
+  else
+    forall(Field f1, int offset |
+      // Let's not deal with bit-fields for now.
+      not f1 instanceof BitField and
+      hasAFieldWithOffset(c1, f1, offset)
+    |
+      hasCompatibleFieldAtOffset(f1, offset, c2)
+    )
+}
+
+/**
+ * An unsafe cast is any explicit cast that is not
+ * a `dynamic_cast`.
+ */
+class UnsafeCast extends Cast {
+  private Class toType;
+
+  UnsafeCast() {
+    (
+      this instanceof CStyleCast
+      or
+      this instanceof StaticCast
+      or
+      this instanceof ReinterpretCast
+    ) and
+    toType = this.getExplicitlyConverted().getUnspecifiedType().stripType() and
+    not this.isImplicit() and
+    exists(TypeDeclarationEntry tde |
+      tde = toType.getDefinition() and
+      not tde.isFromUninstantiatedTemplate(_)
+    )
+  }
+
+  Class getConvertedType() { result = toType }
+
+  /**
+   * Holds if the result of this cast can safely be interpreted as a value of
+   * type `t`.
+   *
+   * The compatibility rules are as follows:
+   *
+   * 1. the result of `(T)x` is compatible with the type `T` for any `T`
+   * 2. the result of `(T)x` is compatible with the type `U` for any `U` such
+   *    that `U` is a subtype of `T`, or `T` is a subtype of `U`.
+   * 3. the result of `(T)x` is compatible with the type `U` if the list
+   *    of fields of `T` is a prefix of the list of fields of `U`.
+   *    For example, if `U` is `struct { unsigned char x; int y; };`
+   *    and `T` is `struct { unsigned char uc; };`.
+   * 4. the result of `(T)x` is compatible with the type `U` if the list
+   *    of fields of `U` is a prefix of the list of fields of `T`.
+   *
+   *    Condition 4 is a bit controversial, since it assumes that the additional
+   *    fields in `T` won't be accessed. This may result in some FNs.
+   */
+  bindingset[this, t]
+  pragma[inline_late]
+  predicate compatibleWith(Type t) {
+    // Conition 1
+    t.stripType() = this.getConvertedType()
+    or
+    // Condition 3
+    prefix(this.getConvertedType(), t.stripType())
+    or
+    // Condition 4
+    prefix(t.stripType(), this.getConvertedType())
+    or
+    // Condition 2 (a)
+    t.stripType().(Class).getABaseClass+() = this.getConvertedType()
+    or
+    // Condition 2 (b)
+    t.stripType() = this.getConvertedType().getABaseClass+()
+  }
+}
+
+/**
+ * Holds if `source` is an allocation that allocates a value of type `type`.
+ */
+predicate isSourceImpl(DataFlow::Node source, Class type) {
+  exists(AllocationExpr alloc |
+    alloc = source.asExpr() and
+    type = alloc.getAllocatedElementType().stripType() and
+    not exists(
+      alloc
+          .(NewOrNewArrayExpr)
+          .getAllocator()
+          .(OperatorNewAllocationFunction)
+          .getPlacementArgument()
+    )
+  ) and
+  exists(TypeDeclarationEntry tde |
+    tde = type.getDefinition() and
+    not tde.isFromUninstantiatedTemplate(_)
+  )
+}
+
+/** A configuration describing flow from an allocation to a potentially unsafe cast. */
+module Config implements DataFlow::ConfigSig {
+  predicate isSource(DataFlow::Node source) { isSourceImpl(source, _) }
+
+  predicate isBarrier(DataFlow::Node node) {
+    // We disable flow through global variables to reduce FPs from infeasible paths
+    node instanceof DataFlow::VariableNode
+    or
+    exists(Class c | c = node.getType().stripType() |
+      not c.hasDefinition()
+      or
+      exists(TypeDeclarationEntry tde |
+        tde = c.getDefinition() and
+        tde.isFromUninstantiatedTemplate(_)
+      )
+    )
+  }
+
+  predicate isSink(DataFlow::Node sink) { sink.asExpr() = any(UnsafeCast cast).getUnconverted() }
+
+  int fieldFlowBranchLimit() { result = 0 }
+}
+
+module Flow = DataFlow::Global<Config>;
+
+predicate relevantType(DataFlow::Node sink, Class allocatedType) {
+  exists(DataFlow::Node source |
+    Flow::flow(source, sink) and
+    isSourceImpl(source, allocatedType)
+  )
+}
+
+predicate isSinkImpl(
+  DataFlow::Node sink, Class allocatedType, Type convertedType, boolean compatible
+) {
+  exists(UnsafeCast cast |
+    relevantType(sink, allocatedType) and
+    sink.asExpr() = cast.getUnconverted() and
+    convertedType = cast.getConvertedType()
+  |
+    if cast.compatibleWith(allocatedType) then compatible = true else compatible = false
+  )
+}
+
+from
+  Flow::PathNode source, Flow::PathNode sink, Type badSourceType, Type sinkType,
+  DataFlow::Node sinkNode
+where
+  Flow::flowPath(source, sink) and
+  sinkNode = sink.getNode() and
+  isSourceImpl(source.getNode(), badSourceType) and
+  isSinkImpl(sinkNode, badSourceType, sinkType, false) and
+  // If there is any flow that would result in a valid cast then we don't
+  // report an alert here. This reduces the number of FPs from infeasible paths
+  // significantly.
+  not exists(DataFlow::Node goodSource, Type goodSourceType |
+    isSourceImpl(goodSource, goodSourceType) and
+    isSinkImpl(sinkNode, goodSourceType, sinkType, true) and
+    Flow::flow(goodSource, sinkNode)
+  )
+select sinkNode, source, sink, "Conversion from $@ to $@ is invalid.", badSourceType,
+  badSourceType.toString(), sinkType, sinkType.toString()

cpp/ql/src/Security/CWE/CWE-843/TypeConfusionBad.cpp

@@ -0,0 +1,7 @@
+void allocate_and_draw_bad() {
+  Shape* shape = new Circle;
+  // ...
+  // BAD: Assumes that shape is always a Square
+  Square* square = static_cast<Square*>(shape);
+  int length = square->getLength();
+}

cpp/ql/src/Security/CWE/CWE-843/TypeConfusionCommon.cpp

@@ -0,0 +1,25 @@
+struct Shape {
+  virtual ~Shape();
+
+  virtual void draw() = 0;
+};
+
+struct Circle : public Shape {
+  Circle();
+
+  void draw() override {
+    /* ... */
+  }
+
+  int getRadius();
+};
+
+struct Square : public Shape {
+  Square();
+
+  void draw() override {
+    /* ... */
+  }
+
+  int getLength();
+};

cpp/ql/src/Security/CWE/CWE-843/TypeConfusionGood.cpp

@@ -0,0 +1,11 @@
+void allocate_and_draw_good() {
+  Shape* shape = new Circle;
+  // ...
+  // GOOD: Dynamically checks if shape is a Square
+  Square* square = dynamic_cast<Square*>(shape);
+  if(square) {
+    int length = square->getLength();
+  } else {
+    // handle error
+  }
+}

cpp/ql/src/Summary/LinesOfUserCode.ql

@@ -4,6 +4,7 @@
  * @kind metric
  * @tags summary
  *       lines-of-code
+ *       debug
  * @id cpp/summary/lines-of-user-code
  */
 

cpp/ql/src/change-notes/2024-02-29-non-constant-format-path-query.md

@@ -1,4 +0,0 @@
----
-category: minorAnalysis
----
-* The "non-constant format string" query (`cpp/non-constant-format`) has been converted to a `path-problem` query.

cpp/ql/src/change-notes/released/0.9.6.md

@@ -1,4 +1,6 @@
----
-category: minorAnalysis
----
+## 0.9.6
+
+### Minor Analysis Improvements
+
+* The "non-constant format string" query (`cpp/non-constant-format`) has been converted to a `path-problem` query.
 * The new C/C++ dataflow and taint-tracking libraries (`semmle.code.cpp.dataflow.new.DataFlow` and `semmle.code.cpp.dataflow.new.TaintTracking`) now implicitly assume that dataflow and taint modelled via `DataFlowFunction` and `TaintFunction` always fully overwrite their buffers and thus act as flow barriers. As a result, many dataflow and taint-tracking queries now produce fewer false positives. To remove this assumption and go back to the previous behavior for a given model, one can override the new `isPartialWrite` predicate.

cpp/ql/src/change-notes/released/0.9.7.md

@@ -0,0 +1,3 @@
+## 0.9.7
+
+No user-facing changes.

cpp/ql/src/change-notes/released/0.9.8.md

@@ -0,0 +1,3 @@
+## 0.9.8
+
+No user-facing changes.

cpp/ql/src/change-notes/released/0.9.9.md

@@ -0,0 +1,15 @@
+## 0.9.9
+
+### New Queries
+
+* Added a new query, `cpp/type-confusion`, to detect casts to invalid types.
+
+### Query Metadata Changes
+
+* `@precision medium` metadata was added to the `cpp/boost/tls-settings-misconfiguration` and `cpp/boost/use-of-deprecated-hardcoded-security-protocol` queries, and these queries are now included in the security-extended suite. The `@name` metadata of these queries were also updated.
+
+### Minor Analysis Improvements
+
+* The "Missing return-value check for a 'scanf'-like function" query (`cpp/missing-check-scanf`) has been converted to a `path-problem` query.
+* The "Potentially uninitialized local variable" query (`cpp/uninitialized-local`) has been converted to a `path-problem` query.
+* Added models for `GLib` allocation and deallocation functions.

cpp/ql/src/codeql-pack.release.yml

@@ -1,2 +1,2 @@
 ---
-lastReleaseVersion: 0.9.5
+lastReleaseVersion: 0.9.9

cpp/ql/src/experimental/Security/CWE/CWE-416/IteratorToExpiredContainer.qhelp

@@ -0,0 +1,53 @@
+<!DOCTYPE qhelp PUBLIC
+  "-//Semmle//qhelp//EN"
+  "qhelp.dtd">
+<qhelp>
+<overview>
+<p>
+Using an iterator owned by a container after the lifetime of the container has expired can lead to undefined behavior.
+This is because the iterator may be invalidated when the container is destroyed, and dereferencing an invalidated iterator is undefined behavior.
+These problems can be hard to spot due to C++'s complex rules for temporary object lifetimes and their extensions.
+</p>
+
+</overview>
+<recommendation>
+
+<p>
+Never create an iterator to a temporary container when the iterator is expected to be used after the container's lifetime has expired.
+</p>
+
+</recommendation>
+<example>
+<p>
+
+</p>
+
+<p>
+The rules for lifetime extension ensures that the code in <code>lifetime_of_temp_extended</code> is well-defined. This is because the
+lifetime of the temporary container returned by <code>get_vector</code> is extended to the end of the loop. However, prior to C++23,
+the lifetime extension rules do not ensure that the container returned by <code>get_vector</code> is extended in <code>lifetime_of_temp_not_extended</code>.
+This is because the temporary container is not bound to a rvalue reference.
+</p>
+<sample src="IteratorToExpiredContainerExtendedLifetime.cpp" />
+
+</example>
+<references>
+
+<li>CERT C Coding Standard:
+<a href="https://wiki.sei.cmu.edu/confluence/display/c/MEM30-C.+Do+not+access+freed+memory">MEM30-C. Do not access freed memory</a>.</li>
+<li>
+OWASP:
+<a href="https://owasp.org/www-community/vulnerabilities/Using_freed_memory">Using freed memory</a>.
+</li>
+<li>
+<a href="https://github.com/isocpp/CppCoreGuidelines/blob/master/docs/Lifetime.pdf">Lifetime safety: Preventing common dangling</a>
+</li>
+<li>
+<a href="https://en.cppreference.com/w/cpp/container">Containers library</a>
+</li>
+<li>
+<a href="https://en.cppreference.com/w/cpp/language/range-for">Range-based for loop (since C++11)</a>
+</li>
+
+</references>
+</qhelp>

cpp/ql/src/experimental/Security/CWE/CWE-416/IteratorToExpiredContainer.ql

@@ -0,0 +1,103 @@
+/**
+ * @name Iterator to expired container
+ * @description Using an iterator owned by a container whose lifetime has expired may lead to unexpected behavior.
+ * @kind problem
+ * @precision high
+ * @id cpp/iterator-to-expired-container
+ * @problem.severity warning
+ * @tags reliability
+ *       security
+ *       external/cwe/cwe-416
+ *       external/cwe/cwe-664
+ */
+
+// IMPORTANT: This query does not currently find anything since it relies on extractor and analysis improvements that hasn't yet been released
+import cpp
+import semmle.code.cpp.ir.IR
+import semmle.code.cpp.dataflow.new.DataFlow
+import semmle.code.cpp.models.implementations.StdContainer
+import semmle.code.cpp.models.implementations.StdMap
+import semmle.code.cpp.models.implementations.Iterator
+
+/**
+ * A configuration to track flow from a temporary variable to the qualifier of
+ * a destructor call
+ */
+module TempToDestructorConfig implements DataFlow::ConfigSig {
+  predicate isSource(DataFlow::Node source) {
+    source.asInstruction().(VariableAddressInstruction).getIRVariable() instanceof IRTempVariable
+  }
+
+  predicate isSink(DataFlow::Node sink) {
+    sink.asOperand().(ThisArgumentOperand).getCall().getStaticCallTarget() instanceof Destructor
+  }
+}
+
+module TempToDestructorFlow = DataFlow::Global<TempToDestructorConfig>;
+
+/**
+ * Gets a `DataFlow::Node` that represents a temporary that will be destroyed
+ * by a call to a destructor, or a `DataFlow::Node` that will transitively be
+ * destroyed by a call to a destructor.
+ *
+ * For the latter case, consider something like:
+ * ```
+ * std::vector<std::vector<int>> get_2d_vector();
+ * auto& v = get_2d_vector()[0];
+ * ```
+ * Given the above, this predicate returns the node corresponding
+ * to `get_2d_vector()[0]` since the temporary `get_2d_vector()` gets
+ * destroyed by a call to `std::vector<std::vector<int>>::~vector`,
+ * and thus the result of `get_2d_vector()[0]` is also an invalid reference.
+ */
+DataFlow::Node getADestroyedNode() {
+  exists(TempToDestructorFlow::PathNode destroyedTemp | destroyedTemp.isSource() |
+    result = destroyedTemp.getNode()
+    or
+    exists(CallInstruction call |
+      result.asInstruction() = call and
+      DataFlow::localFlow(destroyedTemp.getNode(),
+        DataFlow::operandNode(call.getThisArgumentOperand()))
+    |
+      call.getStaticCallTarget() instanceof StdSequenceContainerAt or
+      call.getStaticCallTarget() instanceof StdMapAt
+    )
+  )
+}
+
+predicate isSinkImpl(DataFlow::Node sink, FunctionCall fc) {
+  exists(CallInstruction call |
+    call = sink.asOperand().(ThisArgumentOperand).getCall() and
+    fc = call.getUnconvertedResultExpression() and
+    call.getStaticCallTarget() instanceof BeginOrEndFunction
+  )
+}
+
+/**
+ * Flow from any destroyed object to the qualifier of a `begin` or `end` call
+ */
+module DestroyedToBeginConfig implements DataFlow::ConfigSig {
+  predicate isSource(DataFlow::Node source) { source = getADestroyedNode() }
+
+  predicate isSink(DataFlow::Node sink) { isSinkImpl(sink, _) }
+
+  DataFlow::FlowFeature getAFeature() {
+    // By blocking argument-to-parameter flow we ensure that we don't enter a
+    // function body where the temporary outlives anything inside the function.
+    // This prevents false positives in cases like:
+    // ```cpp
+    // void foo(const std::vector<int>& v) {
+    //   for(auto x : v) { ... } // this is fine since v outlives the loop
+    // }
+    // ...
+    // foo(create_temporary())
+    // ```
+    result instanceof DataFlow::FeatureHasSinkCallContext
+  }
+}
+
+module DestroyedToBeginFlow = DataFlow::Global<DestroyedToBeginConfig>;
+
+from DataFlow::Node source, DataFlow::Node sink, FunctionCall beginOrEnd
+where DestroyedToBeginFlow::flow(source, sink) and isSinkImpl(sink, beginOrEnd)
+select source, "This object is destroyed before $@ is called.", beginOrEnd, beginOrEnd.toString()

cpp/ql/src/experimental/Security/CWE/CWE-416/IteratorToExpiredContainerExtendedLifetime.cpp

@@ -0,0 +1,20 @@
+#include <vector>
+
+std::vector<int> get_vector();
+
+void use(int);
+
+void lifetime_of_temp_extended() {
+  for(auto x : get_vector()) {
+    use(x); // GOOD: The lifetime of the vector returned by `get_vector()` is extended until the end of the loop.
+  }
+}
+
+// Writes the the values of `v` to an external log and returns it unchanged.
+const std::vector<int>& log_and_return_argument(const std::vector<int>& v);
+
+void lifetime_of_temp_not_extended() {
+  for(auto x : log_and_return_argument(get_vector())) {
+    use(x); // BAD: The lifetime of the vector returned by `get_vector()` is not extended, and the behavior is undefined.
+  }
+}

cpp/ql/src/qlpack.yml

@@ -1,5 +1,5 @@
 name: codeql/cpp-queries
-version: 0.9.6-dev
+version: 0.9.9
 groups:
   - cpp
   - queries

cpp/ql/test/examples/expressions/PrintAST.expected

@@ -105,10 +105,24 @@ ConditionDecl.cpp:
 #    3|         getVariableAccess(): [VariableAccess] k
 #    3|             Type = [IntType] int
 #    3|             ValueCategory = prvalue(load)
+#    3|         getInitializingExpr(): [LTExpr] ... < ...
+#    3|             Type = [BoolType] bool
+#    3|             ValueCategory = prvalue
+#    3|           getLesserOperand(): [VariableAccess] j
+#    3|               Type = [IntType] int
+#    3|               ValueCategory = prvalue(load)
+#    3|           getGreaterOperand(): [Literal] 5
+#    3|               Type = [IntType] int
+#    3|               Value = [Literal] 5
+#    3|               ValueCategory = prvalue
 #    3|         getVariableAccess().getFullyConverted(): [CStyleCast] (bool)...
 #    3|             Conversion = [BoolConversion] conversion to bool
 #    3|             Type = [BoolType] bool
 #    3|             ValueCategory = prvalue
+#    3|         getInitializingExpr().getFullyConverted(): [CStyleCast] (int)...
+#    3|             Conversion = [IntegralConversion] integral conversion
+#    3|             Type = [IntType] int
+#    3|             ValueCategory = prvalue
 #    3|       getStmt(): [BlockStmt] { ... }
 #    5|     getStmt(2): [ReturnStmt] return ...
 ConstructorCall.cpp: