121 lines
4.1 KiB
C++
121 lines
4.1 KiB
C++
//=== UndefResultChecker.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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// This defines UndefResultChecker, a builtin check in ExprEngine that
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// performs checks for undefined results of non-assignment binary operators.
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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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#include "clang/StaticAnalyzer/Core/PathSensitive/DynamicExtent.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/Support/raw_ostream.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 UndefResultChecker
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: public Checker< check::PostStmt<BinaryOperator> > {
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const BugType BT{this, "Result of operation is garbage or undefined"};
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public:
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void checkPostStmt(const BinaryOperator *B, CheckerContext &C) const;
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};
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} // end anonymous namespace
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static bool isArrayIndexOutOfBounds(CheckerContext &C, const Expr *Ex) {
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ProgramStateRef state = C.getState();
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if (!isa<ArraySubscriptExpr>(Ex))
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return false;
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SVal Loc = C.getSVal(Ex);
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if (!Loc.isValid())
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return false;
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const MemRegion *MR = Loc.castAs<loc::MemRegionVal>().getRegion();
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const ElementRegion *ER = dyn_cast<ElementRegion>(MR);
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if (!ER)
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return false;
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DefinedOrUnknownSVal Idx = ER->getIndex().castAs<DefinedOrUnknownSVal>();
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DefinedOrUnknownSVal ElementCount = getDynamicElementCount(
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state, ER->getSuperRegion(), C.getSValBuilder(), ER->getValueType());
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ProgramStateRef StInBound, StOutBound;
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std::tie(StInBound, StOutBound) = state->assumeInBoundDual(Idx, ElementCount);
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return StOutBound && !StInBound;
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}
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void UndefResultChecker::checkPostStmt(const BinaryOperator *B,
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CheckerContext &C) const {
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if (C.getSVal(B).isUndef()) {
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// Do not report assignments of uninitialized values inside swap functions.
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// This should allow to swap partially uninitialized structs
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if (const FunctionDecl *EnclosingFunctionDecl =
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dyn_cast<FunctionDecl>(C.getStackFrame()->getDecl()))
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if (C.getCalleeName(EnclosingFunctionDecl) == "swap")
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return;
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// Generate an error node.
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ExplodedNode *N = C.generateErrorNode();
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if (!N)
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return;
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SmallString<256> sbuf;
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llvm::raw_svector_ostream OS(sbuf);
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const Expr *Ex = nullptr;
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bool isLeft = true;
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if (C.getSVal(B->getLHS()).isUndef()) {
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Ex = B->getLHS()->IgnoreParenCasts();
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isLeft = true;
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}
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else if (C.getSVal(B->getRHS()).isUndef()) {
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Ex = B->getRHS()->IgnoreParenCasts();
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isLeft = false;
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}
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if (Ex) {
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OS << "The " << (isLeft ? "left" : "right") << " operand of '"
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<< BinaryOperator::getOpcodeStr(B->getOpcode())
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<< "' is a garbage value";
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if (isArrayIndexOutOfBounds(C, Ex))
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OS << " due to array index out of bounds";
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} else {
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// Neither operand was undefined, but the result is undefined.
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OS << "The result of the '"
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<< BinaryOperator::getOpcodeStr(B->getOpcode())
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<< "' expression is undefined";
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}
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auto report = std::make_unique<PathSensitiveBugReport>(BT, OS.str(), N);
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if (Ex) {
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report->addRange(Ex->getSourceRange());
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bugreporter::trackExpressionValue(N, Ex, *report);
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}
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else
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bugreporter::trackExpressionValue(N, B, *report);
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C.emitReport(std::move(report));
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}
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}
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void ento::registerUndefResultChecker(CheckerManager &mgr) {
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mgr.registerChecker<UndefResultChecker>();
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}
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bool ento::shouldRegisterUndefResultChecker(const CheckerManager &mgr) {
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return true;
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}
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