Add check for pointer arithmetic on non-array variables.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@86538 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/PointerArithChecker.cpp b/lib/Analysis/PointerArithChecker.cpp
new file mode 100644
index 0000000..5f5badb
--- /dev/null
+++ b/lib/Analysis/PointerArithChecker.cpp
@@ -0,0 +1,72 @@
+//=== PointerArithChecker.cpp - Pointer arithmetic checker -----*- C++ -*--===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This files defines PointerArithChecker, a builtin checker that checks for
+// pointer arithmetic on locations other than array elements.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Analysis/PathSensitive/CheckerVisitor.h"
+#include "GRExprEngineInternalChecks.h"
+
+using namespace clang;
+
+namespace {
+class VISIBILITY_HIDDEN PointerArithChecker
+ : public CheckerVisitor<PointerArithChecker> {
+ BuiltinBug *BT;
+public:
+ PointerArithChecker() : BT(0) {}
+ static void *getTag();
+ void PreVisitBinaryOperator(CheckerContext &C, const BinaryOperator *B);
+};
+}
+
+void *PointerArithChecker::getTag() {
+ static int x;
+ return &x;
+}
+
+void PointerArithChecker::PreVisitBinaryOperator(CheckerContext &C,
+ const BinaryOperator *B) {
+ if (B->getOpcode() != BinaryOperator::Sub &&
+ B->getOpcode() != BinaryOperator::Add)
+ return;
+
+ const GRState *state = C.getState();
+ SVal LV = state->getSVal(B->getLHS());
+ SVal RV = state->getSVal(B->getRHS());
+
+ const MemRegion *LR = LV.getAsRegion();
+
+ if (!LR || !RV.isConstant())
+ return;
+
+ // If pointer arithmetic is done on variables of non-array type, this often
+ // means behavior rely on memory organization, which is dangerous.
+ if (isa<VarRegion>(LR) || isa<CodeTextRegion>(LR) ||
+ isa<CompoundLiteralRegion>(LR)) {
+
+ if (ExplodedNode *N = C.GenerateNode(B)) {
+ if (!BT)
+ BT = new BuiltinBug("Dangerous pointer arithmetic",
+ "Pointer arithmetic done on non-array variables "
+ "means reliance on memory layout, which is "
+ "dangerous.");
+ RangedBugReport *R = new RangedBugReport(*BT,BT->getDescription().c_str(),
+ N);
+ R->addRange(B->getSourceRange());
+ C.EmitReport(R);
+ }
+ }
+}
+
+void clang::RegisterPointerArithChecker(GRExprEngine &Eng) {
+ Eng.registerCheck(new PointerArithChecker());
+}