1 files changed, 69 insertions, 0 deletions
diff --git a/clang/lib/StaticAnalyzer/Checkers/PointerArithChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/PointerArithChecker.cpp
new file mode 100644
index 0000000..fe4845b
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Checkers/PointerArithChecker.cpp
@@ -0,0 +1,69 @@
+//=== 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 "ClangSACheckers.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/CheckerManager.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+class PointerArithChecker 
+  : public Checker< check::PreStmt<BinaryOperator> > {
+  mutable OwningPtr<BuiltinBug> BT;
+
+public:
+  void checkPreStmt(const BinaryOperator *B, CheckerContext &C) const;
+};
+}
+
+void PointerArithChecker::checkPreStmt(const BinaryOperator *B,
+                                       CheckerContext &C) const {
+  if (B->getOpcode() != BO_Sub && B->getOpcode() != BO_Add)
+    return;
+
+  ProgramStateRef state = C.getState();
+  const LocationContext *LCtx = C.getLocationContext();
+  SVal LV = state->getSVal(B->getLHS(), LCtx);
+  SVal RV = state->getSVal(B->getRHS(), LCtx);
+
+  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.addTransition()) {
+      if (!BT)
+        BT.reset(new BuiltinBug("Dangerous pointer arithmetic",
+                            "Pointer arithmetic done on non-array variables "
+                            "means reliance on memory layout, which is "
+                            "dangerous."));
+      BugReport *R = new BugReport(*BT, BT->getDescription(), N);
+      R->addRange(B->getSourceRange());
+      C.EmitReport(R);
+    }
+  }
+}
+
+void ento::registerPointerArithChecker(CheckerManager &mgr) {
+  mgr.registerChecker<PointerArithChecker>();
+}