80 lines
2.6 KiB
C++
80 lines
2.6 KiB
C++
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//=== PointerSubChecker.cpp - Pointer subtraction checker ------*- C++ -*--===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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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 "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.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 std::unique_ptr<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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SVal LV = C.getSVal(B->getLHS());
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SVal RV = C.getSVal(B->getRHS());
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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.generateNonFatalErrorNode()) {
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if (!BT)
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BT.reset(
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new BuiltinBug(this, "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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auto R =
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std::make_unique<PathSensitiveBugReport>(*BT, BT->getDescription(), N);
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R->addRange(B->getSourceRange());
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C.emitReport(std::move(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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bool ento::shouldRegisterPointerSubChecker(const CheckerManager &mgr) {
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return true;
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}
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