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//=== 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(), N);
R->addRange(B->getSourceRange());
C.EmitReport(R);
}
}
}
void clang::RegisterPointerArithChecker(GRExprEngine &Eng) {
Eng.registerCheck(new PointerArithChecker());
}
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