Split libAnalysis into two libraries: libAnalysis and libChecker.

(1) libAnalysis is a generic analysis library that can be used by
    Sema.  It defines the CFG, basic dataflow analysis primitives, and
    inexpensive flow-sensitive analyses (e.g. LiveVariables).

(2) libChecker contains the guts of the static analyzer, incuding the
    path-sensitive analysis engine and domain-specific checks.

Now any clients that want to use the frontend to build their own tools
don't need to link in the entire static analyzer.

This change exposes various obvious cleanups that can be made to the
layout of files and headers in libChecker.  More changes pending.  :)

This change also exposed a layering violation between AnalysisContext
and MemRegion.  BlockInvocationContext shouldn't explicitly know about
BlockDataRegions.  For now I've removed the BlockDataRegion* from
BlockInvocationContext (removing context-sensitivity; although this
wasn't used yet).  We need to have a better way to extend
BlockInvocationContext (and any LocationContext) to add
context-sensitivty.

llvm-svn: 94406

1 files changed, 77 insertions, 0 deletions

diff --git a/clang/lib/Checker/PointerSubChecker.cpp b/clang/lib/Checker/PointerSubChecker.cpp
new file mode 100644
index 00000000000..acc848ac8ed
--- /dev/null
+++ b/clang/lib/Checker/PointerSubChecker.cpp
@@ -0,0 +1,77 @@
+//=== PointerSubChecker.cpp - Pointer subtraction 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 PointerSubChecker, a builtin checker that checks for
+// pointer subtractions on two pointers pointing to different memory chunks. 
+// This check corresponds to CWE-469.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Checker/PathSensitive/CheckerVisitor.h"
+#include "GRExprEngineInternalChecks.h"
+
+using namespace clang;
+
+namespace {
+class PointerSubChecker 
+  : public CheckerVisitor<PointerSubChecker> {
+  BuiltinBug *BT;
+public:
+  PointerSubChecker() : BT(0) {}
+  static void *getTag();
+  void PreVisitBinaryOperator(CheckerContext &C, const BinaryOperator *B);
+};
+}
+
+void *PointerSubChecker::getTag() {
+  static int x;
+  return &x;
+}
+
+void PointerSubChecker::PreVisitBinaryOperator(CheckerContext &C,
+                                               const BinaryOperator *B) {
+  // When doing pointer subtraction, if the two pointers do not point to the
+  // same memory chunk, emit a warning.
+  if (B->getOpcode() != BinaryOperator::Sub)
+    return;
+
+  const GRState *state = C.getState();
+  SVal LV = state->getSVal(B->getLHS());
+  SVal RV = state->getSVal(B->getRHS());
+
+  const MemRegion *LR = LV.getAsRegion();
+  const MemRegion *RR = RV.getAsRegion();
+
+  if (!(LR && RR))
+    return;
+
+  const MemRegion *BaseLR = LR->getBaseRegion();
+  const MemRegion *BaseRR = RR->getBaseRegion();
+
+  if (BaseLR == BaseRR)
+    return;
+
+  // Allow arithmetic on different symbolic regions.
+  if (isa<SymbolicRegion>(BaseLR) || isa<SymbolicRegion>(BaseRR))
+    return;
+
+  if (ExplodedNode *N = C.GenerateNode()) {
+    if (!BT)
+      BT = new BuiltinBug("Pointer subtraction", 
+                          "Subtraction of two pointers that do not point to "
+                          "the same memory chunk may cause incorrect result.");
+    RangedBugReport *R = new RangedBugReport(*BT, BT->getDescription(), N);
+    R->addRange(B->getSourceRange());
+    C.EmitReport(R);
+  }
+}
+
+void clang::RegisterPointerSubChecker(GRExprEngine &Eng) {
+  Eng.registerCheck(new PointerSubChecker());
+}