afb13afcf2
A monolithic checker class is hard to maintain. This patch splits it up into a modeling part, the three checkers and a debug checker. The common functions are moved into a library. Differential Revision: https://reviews.llvm.org/D70320
274 lines
9.0 KiB
C++
274 lines
9.0 KiB
C++
//===-- IteratorRangeChecker.cpp ----------------------------------*- 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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// Defines a checker for dereference of the past-the-end iterator and
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// out-of-range increments and decrements.
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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/PathSensitive/CallEvent.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
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#include "Iterator.h"
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using namespace clang;
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using namespace ento;
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using namespace iterator;
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namespace {
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class IteratorRangeChecker
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: public Checker<check::PreCall> {
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std::unique_ptr<BugType> OutOfRangeBugType;
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void verifyDereference(CheckerContext &C, const SVal &Val) const;
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void verifyIncrement(CheckerContext &C, const SVal &Iter) const;
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void verifyDecrement(CheckerContext &C, const SVal &Iter) const;
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void verifyRandomIncrOrDecr(CheckerContext &C, OverloadedOperatorKind Op,
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const SVal &LHS, const SVal &RHS) const;
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void reportBug(const StringRef &Message, const SVal &Val,
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CheckerContext &C, ExplodedNode *ErrNode) const;
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public:
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IteratorRangeChecker();
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void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
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};
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bool isPastTheEnd(ProgramStateRef State, const IteratorPosition &Pos);
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bool isAheadOfRange(ProgramStateRef State, const IteratorPosition &Pos);
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bool isBehindPastTheEnd(ProgramStateRef State, const IteratorPosition &Pos);
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bool isZero(ProgramStateRef State, const NonLoc &Val);
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} //namespace
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IteratorRangeChecker::IteratorRangeChecker() {
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OutOfRangeBugType.reset(
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new BugType(this, "Iterator out of range", "Misuse of STL APIs"));
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}
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void IteratorRangeChecker::checkPreCall(const CallEvent &Call,
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CheckerContext &C) const {
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// Check for out of range access
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const auto *Func = dyn_cast_or_null<FunctionDecl>(Call.getDecl());
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if (!Func)
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return;
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if (Func->isOverloadedOperator()) {
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if (isIncrementOperator(Func->getOverloadedOperator())) {
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// Check for out-of-range incrementions
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if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
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verifyIncrement(C, InstCall->getCXXThisVal());
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} else {
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if (Call.getNumArgs() >= 1) {
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verifyIncrement(C, Call.getArgSVal(0));
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}
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}
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} else if (isDecrementOperator(Func->getOverloadedOperator())) {
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// Check for out-of-range decrementions
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if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
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verifyDecrement(C, InstCall->getCXXThisVal());
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} else {
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if (Call.getNumArgs() >= 1) {
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verifyDecrement(C, Call.getArgSVal(0));
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}
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}
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} else if (isRandomIncrOrDecrOperator(Func->getOverloadedOperator())) {
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if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
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// Check for out-of-range incrementions and decrementions
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if (Call.getNumArgs() >= 1 &&
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Call.getArgExpr(0)->getType()->isIntegralOrEnumerationType()) {
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verifyRandomIncrOrDecr(C, Func->getOverloadedOperator(),
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InstCall->getCXXThisVal(),
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Call.getArgSVal(0));
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}
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} else {
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if (Call.getNumArgs() >= 2 &&
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Call.getArgExpr(1)->getType()->isIntegralOrEnumerationType()) {
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verifyRandomIncrOrDecr(C, Func->getOverloadedOperator(),
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Call.getArgSVal(0), Call.getArgSVal(1));
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}
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}
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} else if (isDereferenceOperator(Func->getOverloadedOperator())) {
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// Check for dereference of out-of-range iterators
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if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
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verifyDereference(C, InstCall->getCXXThisVal());
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} else {
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verifyDereference(C, Call.getArgSVal(0));
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}
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}
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}
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}
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void IteratorRangeChecker::verifyDereference(CheckerContext &C,
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const SVal &Val) const {
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auto State = C.getState();
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const auto *Pos = getIteratorPosition(State, Val);
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if (Pos && isPastTheEnd(State, *Pos)) {
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auto *N = C.generateErrorNode(State);
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if (!N)
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return;
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reportBug("Past-the-end iterator dereferenced.", Val, C, N);
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return;
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}
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}
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void IteratorRangeChecker::verifyIncrement(CheckerContext &C,
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const SVal &Iter) const {
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auto &BVF = C.getSValBuilder().getBasicValueFactory();
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verifyRandomIncrOrDecr(C, OO_Plus, Iter,
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nonloc::ConcreteInt(BVF.getValue(llvm::APSInt::get(1))));
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}
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void IteratorRangeChecker::verifyDecrement(CheckerContext &C,
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const SVal &Iter) const {
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auto &BVF = C.getSValBuilder().getBasicValueFactory();
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verifyRandomIncrOrDecr(C, OO_Minus, Iter,
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nonloc::ConcreteInt(BVF.getValue(llvm::APSInt::get(1))));
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}
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void IteratorRangeChecker::verifyRandomIncrOrDecr(CheckerContext &C,
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OverloadedOperatorKind Op,
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const SVal &LHS,
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const SVal &RHS) const {
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auto State = C.getState();
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auto Value = RHS;
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if (auto ValAsLoc = RHS.getAs<Loc>()) {
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Value = State->getRawSVal(*ValAsLoc);
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}
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if (Value.isUnknown())
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return;
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// Incremention or decremention by 0 is never a bug.
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if (isZero(State, Value.castAs<NonLoc>()))
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return;
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// The result may be the past-end iterator of the container, but any other
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// out of range position is undefined behaviour
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auto StateAfter = advancePosition(State, LHS, Op, Value);
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if (!StateAfter)
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return;
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const auto *PosAfter = getIteratorPosition(StateAfter, LHS);
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assert(PosAfter &&
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"Iterator should have position after successful advancement");
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if (isAheadOfRange(State, *PosAfter)) {
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auto *N = C.generateErrorNode(State);
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if (!N)
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return;
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reportBug("Iterator decremented ahead of its valid range.", LHS,
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C, N);
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}
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if (isBehindPastTheEnd(State, *PosAfter)) {
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auto *N = C.generateErrorNode(State);
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if (!N)
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return;
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reportBug("Iterator incremented behind the past-the-end "
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"iterator.", LHS, C, N);
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}
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}
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void IteratorRangeChecker::reportBug(const StringRef &Message,
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const SVal &Val, CheckerContext &C,
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ExplodedNode *ErrNode) const {
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auto R = std::make_unique<PathSensitiveBugReport>(*OutOfRangeBugType, Message,
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ErrNode);
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R->markInteresting(Val);
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C.emitReport(std::move(R));
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}
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namespace {
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bool isLess(ProgramStateRef State, SymbolRef Sym1, SymbolRef Sym2);
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bool isGreater(ProgramStateRef State, SymbolRef Sym1, SymbolRef Sym2);
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bool isEqual(ProgramStateRef State, SymbolRef Sym1, SymbolRef Sym2);
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bool isZero(ProgramStateRef State, const NonLoc &Val) {
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auto &BVF = State->getBasicVals();
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return compare(State, Val,
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nonloc::ConcreteInt(BVF.getValue(llvm::APSInt::get(0))),
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BO_EQ);
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}
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bool isPastTheEnd(ProgramStateRef State, const IteratorPosition &Pos) {
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const auto *Cont = Pos.getContainer();
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const auto *CData = getContainerData(State, Cont);
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if (!CData)
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return false;
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const auto End = CData->getEnd();
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if (End) {
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if (isEqual(State, Pos.getOffset(), End)) {
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return true;
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}
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}
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return false;
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}
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bool isAheadOfRange(ProgramStateRef State, const IteratorPosition &Pos) {
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const auto *Cont = Pos.getContainer();
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const auto *CData = getContainerData(State, Cont);
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if (!CData)
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return false;
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const auto Beg = CData->getBegin();
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if (Beg) {
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if (isLess(State, Pos.getOffset(), Beg)) {
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return true;
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}
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}
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return false;
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}
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bool isBehindPastTheEnd(ProgramStateRef State, const IteratorPosition &Pos) {
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const auto *Cont = Pos.getContainer();
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const auto *CData = getContainerData(State, Cont);
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if (!CData)
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return false;
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const auto End = CData->getEnd();
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if (End) {
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if (isGreater(State, Pos.getOffset(), End)) {
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return true;
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}
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}
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return false;
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}
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bool isLess(ProgramStateRef State, SymbolRef Sym1, SymbolRef Sym2) {
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return compare(State, Sym1, Sym2, BO_LT);
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}
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bool isGreater(ProgramStateRef State, SymbolRef Sym1, SymbolRef Sym2) {
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return compare(State, Sym1, Sym2, BO_GT);
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}
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bool isEqual(ProgramStateRef State, SymbolRef Sym1, SymbolRef Sym2) {
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return compare(State, Sym1, Sym2, BO_EQ);
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}
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} // namespace
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void ento::registerIteratorRangeChecker(CheckerManager &mgr) {
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mgr.registerChecker<IteratorRangeChecker>();
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}
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bool ento::shouldRegisterIteratorRangeChecker(const LangOptions &LO) {
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return true;
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}
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