Merge pull request #11311 from MathiasVP/repair-mustflow

C++: Repair `MustFlow` library for use-use flow

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

@@ -26,11 +26,11 @@ predicate intentionallyReturnsStackPointer(Function f) {
 class ReturnStackAllocatedMemoryConfig extends MustFlowConfiguration {
   ReturnStackAllocatedMemoryConfig() { this = "ReturnStackAllocatedMemoryConfig" }
 
-  override predicate isSource(DataFlow::Node source) {
+  override predicate isSource(Instruction source) {
     // Holds if `source` is a node that represents the use of a stack variable
     exists(VariableAddressInstruction var, Function func |
-      var = source.asInstruction() and
-      func = var.getEnclosingFunction() and
+      var = source and
+      func = source.getEnclosingFunction() and
       var.getAstVariable() instanceof StackVariable and
       // Pointer-to-member types aren't properly handled in the dbscheme.
       not var.getResultType() instanceof PointerToMemberType and
@@ -40,7 +40,7 @@ class ReturnStackAllocatedMemoryConfig extends MustFlowConfiguration {
     )
   }
 
-  override predicate isSink(DataFlow::Node sink) {
+  override predicate isSink(Operand sink) {
     // Holds if `sink` is a node that represents the `StoreInstruction` that is subsequently used in
     // a `ReturnValueInstruction`.
     // We use the `StoreInstruction` instead of the instruction that defines the
@@ -48,7 +48,7 @@ class ReturnStackAllocatedMemoryConfig extends MustFlowConfiguration {
     exists(StoreInstruction store |
       store.getDestinationAddress().(VariableAddressInstruction).getIRVariable() instanceof
         IRReturnVariable and
-      sink.asOperand() = store.getSourceValueOperand()
+      sink = store.getSourceValueOperand()
     )
   }
 
@@ -77,10 +77,10 @@ class ReturnStackAllocatedMemoryConfig extends MustFlowConfiguration {
    * }
    * ```
    */
-  override predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {
-    node2.asInstruction().(FieldAddressInstruction).getObjectAddressOperand() = node1.asOperand()
+  override predicate isAdditionalFlowStep(Operand node1, Instruction node2) {
+    node2.(FieldAddressInstruction).getObjectAddressOperand() = node1
     or
-    node2.asInstruction().(PointerOffsetInstruction).getLeftOperand() = node1.asOperand()
+    node2.(PointerOffsetInstruction).getLeftOperand() = node1
   }
 }
 
@@ -89,6 +89,6 @@ from
   ReturnStackAllocatedMemoryConfig conf
 where
   conf.hasFlowPath(pragma[only_bind_into](source), pragma[only_bind_into](sink)) and
-  source.getNode().asInstruction() = var
-select sink.getNode(), source, sink, "May return stack-allocated memory from $@.", var.getAst(),
-  var.getAst().toString()
+  source.getInstruction() = var
+select sink.getInstruction(), source, sink, "May return stack-allocated memory from $@.",
+  var.getAst(), var.getAst().toString()

cpp/ql/src/Likely Bugs/OO/UnsafeUseOfThis.ql

@@ -22,37 +22,40 @@ import PathGraph
 class UnsafeUseOfThisConfig extends MustFlowConfiguration {
   UnsafeUseOfThisConfig() { this = "UnsafeUseOfThisConfig" }
 
-  override predicate isSource(DataFlow::Node source) { isSource(source, _, _) }
+  override predicate isSource(Instruction source) { isSource(source, _, _) }
 
-  override predicate isSink(DataFlow::Node sink) { isSink(sink, _) }
+  override predicate isSink(Operand sink) { isSink(sink, _) }
 }
 
-/** Holds if `instr` is a `this` pointer used by the call instruction `call`. */
-predicate isSink(DataFlow::Node sink, CallInstruction call) {
+/** Holds if `sink` is a `this` pointer used by the call instruction `call`. */
+predicate isSink(Operand sink, CallInstruction call) {
   exists(PureVirtualFunction func |
     call.getStaticCallTarget() = func and
-    call.getThisArgument() = sink.asInstruction() and
+    call.getThisArgumentOperand() = sink and
     // Weed out implicit calls to destructors of a base class
     not func instanceof Destructor
   )
 }
 
-/** Holds if `init` initializes the `this` pointer in class `c`. */
-predicate isSource(DataFlow::Node source, string msg, Class c) {
-  exists(InitializeParameterInstruction init | init = source.asInstruction() |
-    (
-      exists(Constructor func |
-        not func instanceof CopyConstructor and
-        not func instanceof MoveConstructor and
-        func = init.getEnclosingFunction() and
-        msg = "construction"
-      )
-      or
-      init.getEnclosingFunction() instanceof Destructor and msg = "destruction"
-    ) and
-    init.getIRVariable() instanceof IRThisVariable and
-    init.getEnclosingFunction().getDeclaringType() = c
-  )
+/**
+ * Holds if `source` initializes the `this` pointer in class `c`.
+ *
+ * The string `msg` describes whether the enclosing function is a
+ * constructor or destructor.
+ */
+predicate isSource(InitializeParameterInstruction source, string msg, Class c) {
+  (
+    exists(Constructor func |
+      not func instanceof CopyConstructor and
+      not func instanceof MoveConstructor and
+      func = source.getEnclosingFunction() and
+      msg = "construction"
+    )
+    or
+    source.getEnclosingFunction() instanceof Destructor and msg = "destruction"
+  ) and
+  source.getIRVariable() instanceof IRThisVariable and
+  source.getEnclosingFunction().getDeclaringType() = c
 }
 
 /**
@@ -68,8 +71,8 @@ predicate flows(
 ) {
   exists(UnsafeUseOfThisConfig conf |
     conf.hasFlowPath(source, sink) and
-    isSource(source.getNode(), msg, sourceClass) and
-    isSink(sink.getNode(), call)
+    isSource(source.getInstruction(), msg, sourceClass) and
+    isSink(sink.getInstruction().getAUse(), call)
   )
 }