27 cppnon constant format bug local

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

@@ -621,6 +621,26 @@ class GlobalLikeVariable extends Variable {
   }
 }
 
+/**
+ * Returns the smallest indirection for `use`.
+ *
+ * For most types this is `1`, but for `ArrayType`s (which are allocated on
+ * the stack) this is `0`
+ */
+private int getLowerForGlobalUse(Ssa::GlobalUse use) {
+  if use.getUnspecifiedType() instanceof Cpp::ArrayType then result = 0 else result = 1
+}
+
+/**
+ * Returns the smallest indirection for `def`.
+ *
+ * For most types this is `1`, but for `ArrayType`s (which are allocated on
+ * the stack) this is `0`
+ */
+private int getLowerForGlobalDef(Ssa::GlobalDef def) {
+  if def.getUnspecifiedType() instanceof Cpp::ArrayType then result = 0 else result = 1
+}
+
 /**
  * Holds if data can flow from `node1` to `node2` in a way that loses the
  * calling context. For example, this would happen with flow through a
@@ -632,20 +652,20 @@ predicate jumpStep(Node n1, Node n2) {
       v = globalUse.getVariable() and
       n1.(FinalGlobalValue).getGlobalUse() = globalUse
     |
-      globalUse.getIndirectionIndex() = 1 and
+      globalUse.getIndirection() = getLowerForGlobalUse(globalUse) and
       v = n2.asVariable()
       or
-      v = n2.asIndirectVariable(globalUse.getIndirectionIndex())
+      v = n2.asIndirectVariable(globalUse.getIndirection())
     )
     or
     exists(Ssa::GlobalDef globalDef |
       v = globalDef.getVariable() and
       n2.(InitialGlobalValue).getGlobalDef() = globalDef
     |
-      globalDef.getIndirectionIndex() = 1 and
+      globalDef.getIndirection() = getLowerForGlobalDef(globalDef) and
       v = n1.asVariable()
       or
-      v = n1.asIndirectVariable(globalDef.getIndirectionIndex())
+      v = n1.asIndirectVariable(globalDef.getIndirection())
     )
   )
 }

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

@@ -34,7 +34,11 @@ cached
 private newtype TIRDataFlowNode =
   TNode0(Node0Impl node) { DataFlowImplCommon::forceCachingInSameStage() } or
   TVariableNode(Variable var, int indirectionIndex) {
-    indirectionIndex = [1 .. Ssa::getMaxIndirectionsForType(var.getUnspecifiedType())]
+    exists(int lower |
+      if var.getUnspecifiedType() instanceof ArrayType then lower = 0 else lower = 1
+    |
+      indirectionIndex = [lower .. Ssa::getMaxIndirectionsForType(var.getUnspecifiedType())]
+    )
   } or
   TPostFieldUpdateNode(FieldAddress operand, int indirectionIndex) {
     indirectionIndex =
@@ -345,15 +349,23 @@ class Node extends TIRDataFlowNode {
    * Gets the variable corresponding to this node, if any. This can be used for
    * modeling flow in and out of global variables.
    */
-  Variable asVariable() { this = TVariableNode(result, 1) }
+  Variable asVariable() {
+    if result.getUnspecifiedType() instanceof ArrayType
+    then this = TVariableNode(result, 0)
+    else this = TVariableNode(result, 1)
+  }
 
   /**
    * Gets the `indirectionIndex`'th indirection of this node's underlying variable, if any.
    *
    * This can be used for modeling flow in and out of global variables.
    */
   Variable asIndirectVariable(int indirectionIndex) {
-    indirectionIndex > 1 and
+    (
+      if result.getUnspecifiedType() instanceof ArrayType
+      then indirectionIndex > 0
+      else indirectionIndex > 1
+    ) and
     this = TVariableNode(result, indirectionIndex)
   }
 

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

@@ -113,22 +113,12 @@ private newtype TDefOrUseImpl =
   TGlobalUse(GlobalLikeVariable v, IRFunction f, int indirectionIndex) {
     // Represents a final "use" of a global variable to ensure that
     // the assignment to a global variable isn't ruled out as dead.
-    exists(VariableAddressInstruction vai, int defIndex |
-      vai.getEnclosingIRFunction() = f and
-      vai.getAstVariable() = v and
-      isDef(_, _, _, vai, _, defIndex) and
-      indirectionIndex = [0 .. defIndex] + 1
-    )
+    isGlobalUse(v, f, _, indirectionIndex)
   } or
   TGlobalDefImpl(GlobalLikeVariable v, IRFunction f, int indirectionIndex) {
     // Represents the initial "definition" of a global variable when entering
     // a function body.
-    exists(VariableAddressInstruction vai |
-      vai.getEnclosingIRFunction() = f and
-      vai.getAstVariable() = v and
-      isUse(_, _, vai, _, indirectionIndex) and
-      not isDef(_, _, vai.getAUse(), _, _, _)
-    )
+    isGlobalDefImpl(v, f, _, indirectionIndex)
   } or
   TIteratorDef(
     Operand iteratorDerefAddress, BaseSourceVariableInstruction container, int indirectionIndex
@@ -150,6 +140,27 @@ private newtype TDefOrUseImpl =
     )
   }
 
+private predicate isGlobalUse(
+  GlobalLikeVariable v, IRFunction f, int indirection, int indirectionIndex
+) {
+  exists(VariableAddressInstruction vai |
+    vai.getEnclosingIRFunction() = f and
+    vai.getAstVariable() = v and
+    isDef(_, _, _, vai, indirection, indirectionIndex)
+  )
+}
+
+private predicate isGlobalDefImpl(
+  GlobalLikeVariable v, IRFunction f, int indirection, int indirectionIndex
+) {
+  exists(VariableAddressInstruction vai |
+    vai.getEnclosingIRFunction() = f and
+    vai.getAstVariable() = v and
+    isUse(_, _, vai, indirection, indirectionIndex) and
+    not isDef(_, _, _, vai, _, indirectionIndex)
+  )
+}
+
 private predicate unspecifiedTypeIsModifiableAt(Type unspecified, int indirectionIndex) {
   indirectionIndex = [1 .. getIndirectionForUnspecifiedType(unspecified).getNumberOfIndirections()] and
   exists(CppType cppType |
@@ -438,7 +449,7 @@ class GlobalUse extends UseImpl, TGlobalUse {
 
   override FinalGlobalValue getNode() { result.getGlobalUse() = this }
 
-  override int getIndirection() { result = ind + 1 }
+  override int getIndirection() { isGlobalUse(global, f, result, ind) }
 
   /** Gets the global variable associated with this use. */
   GlobalLikeVariable getVariable() { result = global }
@@ -460,7 +471,9 @@ class GlobalUse extends UseImpl, TGlobalUse {
     )
   }
 
-  override SourceVariable getSourceVariable() { sourceVariableIsGlobal(result, global, f, ind) }
+  override SourceVariable getSourceVariable() {
+    sourceVariableIsGlobal(result, global, f, this.getIndirection())
+  }
 
   final override Cpp::Location getLocation() { result = f.getLocation() }
 
@@ -501,16 +514,18 @@ class GlobalDefImpl extends DefOrUseImpl, TGlobalDefImpl {
 
   /** Gets the global variable associated with this definition. */
   override SourceVariable getSourceVariable() {
-    sourceVariableIsGlobal(result, global, f, indirectionIndex)
+    sourceVariableIsGlobal(result, global, f, this.getIndirection())
   }
 
+  int getIndirection() { result = indirectionIndex }
+
   /**
    * Gets the type of this use after specifiers have been deeply stripped
    * and typedefs have been resolved.
    */
   Type getUnspecifiedType() { result = global.getUnspecifiedType() }
 
-  override string toString() { result = "GlobalDef" }
+  override string toString() { result = "Def of " + this.getSourceVariable() }
 
   override Location getLocation() { result = f.getLocation() }
 
@@ -980,7 +995,7 @@ class GlobalDef extends TGlobalDef, SsaDefOrUse {
   final override Location getLocation() { result = global.getLocation() }
 
   /** Gets a textual representation of this definition. */
-  override string toString() { result = "GlobalDef" }
+  override string toString() { result = global.toString() }
 
   /**
    * Holds if this definition has index `index` in block `block`, and
@@ -990,6 +1005,9 @@ class GlobalDef extends TGlobalDef, SsaDefOrUse {
     global.hasIndexInBlock(block, index, sv)
   }
 
+  /** Gets the indirection index of this definition. */
+  int getIndirection() { result = global.getIndirection() }
+
   /** Gets the indirection index of this definition. */
   int getIndirectionIndex() { result = global.getIndirectionIndex() }