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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 "ClangSACheckers.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
using namespace clang;
using namespace ento;
namespace {
class PointerArithChecker
: public Checker< check::PreStmt<BinaryOperator> > {
mutable std::unique_ptr<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(this, "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>();
}
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