76 lines
2.5 KiB
C++
76 lines
2.5 KiB
C++
//=== PointerSubChecker.cpp - Pointer subtraction checker ------*- C++ -*--===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This files defines PointerSubChecker, a builtin checker that checks for
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// pointer subtractions on two pointers pointing to different memory chunks.
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// This check corresponds to CWE-469.
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//
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//===----------------------------------------------------------------------===//
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#include "ClangSACheckers.h"
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#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
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#include "clang/StaticAnalyzer/Core/Checker.h"
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#include "clang/StaticAnalyzer/Core/CheckerManager.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
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using namespace clang;
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using namespace ento;
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namespace {
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class PointerSubChecker
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: public Checker< check::PreStmt<BinaryOperator> > {
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mutable OwningPtr<BuiltinBug> BT;
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public:
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void checkPreStmt(const BinaryOperator *B, CheckerContext &C) const;
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};
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}
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void PointerSubChecker::checkPreStmt(const BinaryOperator *B,
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CheckerContext &C) const {
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// When doing pointer subtraction, if the two pointers do not point to the
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// same memory chunk, emit a warning.
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if (B->getOpcode() != BO_Sub)
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return;
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ProgramStateRef state = C.getState();
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const LocationContext *LCtx = C.getLocationContext();
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SVal LV = state->getSVal(B->getLHS(), LCtx);
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SVal RV = state->getSVal(B->getRHS(), LCtx);
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const MemRegion *LR = LV.getAsRegion();
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const MemRegion *RR = RV.getAsRegion();
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if (!(LR && RR))
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return;
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const MemRegion *BaseLR = LR->getBaseRegion();
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const MemRegion *BaseRR = RR->getBaseRegion();
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if (BaseLR == BaseRR)
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return;
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// Allow arithmetic on different symbolic regions.
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if (isa<SymbolicRegion>(BaseLR) || isa<SymbolicRegion>(BaseRR))
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return;
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if (ExplodedNode *N = C.addTransition()) {
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if (!BT)
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BT.reset(new BuiltinBug("Pointer subtraction",
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"Subtraction of two pointers that do not point to "
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"the same memory chunk may cause incorrect result."));
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BugReport *R = new BugReport(*BT, BT->getDescription(), N);
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R->addRange(B->getSourceRange());
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C.emitReport(R);
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}
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}
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void ento::registerPointerSubChecker(CheckerManager &mgr) {
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mgr.registerChecker<PointerSubChecker>();
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}
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