//=== 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>(); }