da6ac9564b
Added the support for annotating a constructor's argument with [[clang::noescape]]. We explicitly ignore CXXConstructExpr which is visited as a part of CallExpr so that construction of closures like Function, CompletionHandler, etc... don't result in a warning.
343 lines
12 KiB
C++
343 lines
12 KiB
C++
//=======- UncountedLambdaCapturesChecker.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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#include "ASTUtils.h"
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#include "DiagOutputUtils.h"
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#include "PtrTypesSemantics.h"
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#include "clang/AST/CXXInheritance.h"
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#include "clang/AST/DynamicRecursiveASTVisitor.h"
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#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
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#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.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 <optional>
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using namespace clang;
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using namespace ento;
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namespace {
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class UncountedLambdaCapturesChecker
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: public Checker<check::ASTDecl<TranslationUnitDecl>> {
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private:
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BugType Bug{this, "Lambda capture of uncounted variable",
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"WebKit coding guidelines"};
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mutable BugReporter *BR = nullptr;
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TrivialFunctionAnalysis TFA;
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public:
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void checkASTDecl(const TranslationUnitDecl *TUD, AnalysisManager &MGR,
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BugReporter &BRArg) const {
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BR = &BRArg;
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// The calls to checkAST* from AnalysisConsumer don't
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// visit template instantiations or lambda classes. We
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// want to visit those, so we make our own RecursiveASTVisitor.
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struct LocalVisitor : DynamicRecursiveASTVisitor {
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const UncountedLambdaCapturesChecker *Checker;
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llvm::DenseSet<const DeclRefExpr *> DeclRefExprsToIgnore;
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llvm::DenseSet<const LambdaExpr *> LambdasToIgnore;
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llvm::DenseSet<const CXXConstructExpr *> ConstructToIgnore;
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QualType ClsType;
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explicit LocalVisitor(const UncountedLambdaCapturesChecker *Checker)
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: Checker(Checker) {
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assert(Checker);
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ShouldVisitTemplateInstantiations = true;
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ShouldVisitImplicitCode = false;
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}
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bool TraverseCXXMethodDecl(CXXMethodDecl *CXXMD) override {
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llvm::SaveAndRestore SavedDecl(ClsType);
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if (CXXMD->isInstance())
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ClsType = CXXMD->getThisType();
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return DynamicRecursiveASTVisitor::TraverseCXXMethodDecl(CXXMD);
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}
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bool shouldCheckThis() {
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auto result = !ClsType.isNull() ? isUnsafePtr(ClsType) : std::nullopt;
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return result && *result;
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}
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bool VisitLambdaExpr(LambdaExpr *L) override {
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if (LambdasToIgnore.contains(L))
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return true;
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Checker->visitLambdaExpr(L, shouldCheckThis());
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return true;
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}
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bool VisitVarDecl(VarDecl *VD) override {
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auto *Init = VD->getInit();
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if (!Init)
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return true;
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auto *L = dyn_cast_or_null<LambdaExpr>(Init->IgnoreParenCasts());
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if (!L)
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return true;
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LambdasToIgnore.insert(L); // Evaluate lambdas in VisitDeclRefExpr.
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return true;
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}
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bool VisitDeclRefExpr(DeclRefExpr *DRE) override {
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if (DeclRefExprsToIgnore.contains(DRE))
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return true;
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auto *VD = dyn_cast_or_null<VarDecl>(DRE->getDecl());
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if (!VD)
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return true;
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auto *Init = VD->getInit();
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if (!Init)
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return true;
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auto *L = dyn_cast_or_null<LambdaExpr>(Init->IgnoreParenCasts());
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if (!L)
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return true;
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LambdasToIgnore.insert(L);
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Checker->visitLambdaExpr(L, shouldCheckThis());
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return true;
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}
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// WTF::switchOn(T, F... f) is a variadic template function and couldn't
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// be annotated with NOESCAPE. We hard code it here to workaround that.
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bool shouldTreatAllArgAsNoEscape(FunctionDecl *Decl) {
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auto *NsDecl = Decl->getParent();
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if (!NsDecl || !isa<NamespaceDecl>(NsDecl))
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return false;
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return safeGetName(NsDecl) == "WTF" && safeGetName(Decl) == "switchOn";
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}
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bool VisitCXXConstructExpr(CXXConstructExpr *CE) override {
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if (ConstructToIgnore.contains(CE))
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return true;
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if (auto *Callee = CE->getConstructor()) {
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unsigned ArgIndex = 0;
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for (auto *Param : Callee->parameters()) {
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if (ArgIndex >= CE->getNumArgs())
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return true;
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auto *Arg = CE->getArg(ArgIndex)->IgnoreParenCasts();
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if (auto *L = findLambdaInArg(Arg)) {
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LambdasToIgnore.insert(L);
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if (!Param->hasAttr<NoEscapeAttr>())
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Checker->visitLambdaExpr(L, shouldCheckThis());
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}
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++ArgIndex;
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}
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}
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return true;
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}
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bool VisitCallExpr(CallExpr *CE) override {
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checkCalleeLambda(CE);
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if (auto *Callee = CE->getDirectCallee()) {
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unsigned ArgIndex = isa<CXXOperatorCallExpr>(CE);
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bool TreatAllArgsAsNoEscape = shouldTreatAllArgAsNoEscape(Callee);
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for (auto *Param : Callee->parameters()) {
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if (ArgIndex >= CE->getNumArgs())
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return true;
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auto *Arg = CE->getArg(ArgIndex)->IgnoreParenCasts();
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if (auto *L = findLambdaInArg(Arg)) {
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LambdasToIgnore.insert(L);
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if (!Param->hasAttr<NoEscapeAttr>() && !TreatAllArgsAsNoEscape)
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Checker->visitLambdaExpr(L, shouldCheckThis());
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}
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++ArgIndex;
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}
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}
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return true;
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}
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LambdaExpr *findLambdaInArg(Expr *E) {
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if (auto *Lambda = dyn_cast_or_null<LambdaExpr>(E))
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return Lambda;
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auto *TempExpr = dyn_cast_or_null<CXXBindTemporaryExpr>(E);
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if (!TempExpr)
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return nullptr;
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E = TempExpr->getSubExpr()->IgnoreParenCasts();
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if (!E)
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return nullptr;
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if (auto *Lambda = dyn_cast<LambdaExpr>(E))
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return Lambda;
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auto *CE = dyn_cast_or_null<CXXConstructExpr>(E);
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if (!CE || !CE->getNumArgs())
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return nullptr;
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auto *CtorArg = CE->getArg(0)->IgnoreParenCasts();
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if (!CtorArg)
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return nullptr;
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if (auto *Lambda = dyn_cast<LambdaExpr>(CtorArg)) {
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ConstructToIgnore.insert(CE);
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return Lambda;
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}
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auto *DRE = dyn_cast<DeclRefExpr>(CtorArg);
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if (!DRE)
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return nullptr;
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auto *VD = dyn_cast_or_null<VarDecl>(DRE->getDecl());
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if (!VD)
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return nullptr;
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auto *Init = VD->getInit();
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if (!Init)
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return nullptr;
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TempExpr = dyn_cast<CXXBindTemporaryExpr>(Init->IgnoreParenCasts());
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if (!TempExpr)
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return nullptr;
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ConstructToIgnore.insert(CE);
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return dyn_cast_or_null<LambdaExpr>(TempExpr->getSubExpr());
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}
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void checkCalleeLambda(CallExpr *CE) {
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auto *Callee = CE->getCallee();
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if (!Callee)
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return;
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auto *DRE = dyn_cast<DeclRefExpr>(Callee->IgnoreParenCasts());
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if (!DRE)
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return;
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auto *MD = dyn_cast_or_null<CXXMethodDecl>(DRE->getDecl());
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if (!MD || CE->getNumArgs() < 1)
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return;
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auto *Arg = CE->getArg(0)->IgnoreParenCasts();
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if (auto *L = dyn_cast_or_null<LambdaExpr>(Arg)) {
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LambdasToIgnore.insert(L); // Calling a lambda upon creation is safe.
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return;
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}
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auto *ArgRef = dyn_cast<DeclRefExpr>(Arg);
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if (!ArgRef)
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return;
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auto *VD = dyn_cast_or_null<VarDecl>(ArgRef->getDecl());
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if (!VD)
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return;
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auto *Init = VD->getInit();
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if (!Init)
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return;
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auto *L = dyn_cast_or_null<LambdaExpr>(Init->IgnoreParenCasts());
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if (!L)
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return;
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DeclRefExprsToIgnore.insert(ArgRef);
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LambdasToIgnore.insert(L);
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Checker->visitLambdaExpr(L, shouldCheckThis(),
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/* ignoreParamVarDecl */ true);
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}
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};
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LocalVisitor visitor(this);
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visitor.TraverseDecl(const_cast<TranslationUnitDecl *>(TUD));
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}
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void visitLambdaExpr(LambdaExpr *L, bool shouldCheckThis,
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bool ignoreParamVarDecl = false) const {
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if (TFA.isTrivial(L->getBody()))
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return;
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for (const LambdaCapture &C : L->captures()) {
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if (C.capturesVariable()) {
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ValueDecl *CapturedVar = C.getCapturedVar();
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if (ignoreParamVarDecl && isa<ParmVarDecl>(CapturedVar))
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continue;
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QualType CapturedVarQualType = CapturedVar->getType();
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auto IsUncountedPtr = isUnsafePtr(CapturedVar->getType());
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if (IsUncountedPtr && *IsUncountedPtr)
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reportBug(C, CapturedVar, CapturedVarQualType);
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} else if (C.capturesThis() && shouldCheckThis) {
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if (ignoreParamVarDecl) // this is always a parameter to this function.
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continue;
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bool hasProtectThis = false;
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for (const LambdaCapture &OtherCapture : L->captures()) {
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if (!OtherCapture.capturesVariable())
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continue;
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if (auto *ValueDecl = OtherCapture.getCapturedVar()) {
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if (protectThis(ValueDecl)) {
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hasProtectThis = true;
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break;
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}
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}
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}
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if (!hasProtectThis)
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reportBugOnThisPtr(C);
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}
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}
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}
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bool protectThis(const ValueDecl *ValueDecl) const {
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auto *VD = dyn_cast<VarDecl>(ValueDecl);
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if (!VD)
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return false;
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auto *Init = VD->getInit()->IgnoreParenCasts();
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if (!Init)
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return false;
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auto *BTE = dyn_cast<CXXBindTemporaryExpr>(Init);
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if (!BTE)
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return false;
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auto *CE = dyn_cast_or_null<CXXConstructExpr>(BTE->getSubExpr());
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if (!CE)
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return false;
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auto *Ctor = CE->getConstructor();
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if (!Ctor)
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return false;
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auto clsName = safeGetName(Ctor->getParent());
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if (!isRefType(clsName) || !CE->getNumArgs())
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return false;
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auto *Arg = CE->getArg(0)->IgnoreParenCasts();
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while (auto *UO = dyn_cast<UnaryOperator>(Arg)) {
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auto OpCode = UO->getOpcode();
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if (OpCode == UO_Deref || OpCode == UO_AddrOf)
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Arg = UO->getSubExpr();
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else
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break;
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}
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return isa<CXXThisExpr>(Arg);
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}
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void reportBug(const LambdaCapture &Capture, ValueDecl *CapturedVar,
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const QualType T) const {
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assert(CapturedVar);
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SmallString<100> Buf;
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llvm::raw_svector_ostream Os(Buf);
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if (Capture.isExplicit()) {
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Os << "Captured ";
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} else {
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Os << "Implicitly captured ";
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}
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if (T->isPointerType()) {
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Os << "raw-pointer ";
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} else {
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assert(T->isReferenceType());
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Os << "reference ";
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}
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printQuotedQualifiedName(Os, Capture.getCapturedVar());
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Os << " to ref-counted type or CheckedPtr-capable type is unsafe.";
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PathDiagnosticLocation BSLoc(Capture.getLocation(), BR->getSourceManager());
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auto Report = std::make_unique<BasicBugReport>(Bug, Os.str(), BSLoc);
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BR->emitReport(std::move(Report));
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}
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void reportBugOnThisPtr(const LambdaCapture &Capture) const {
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SmallString<100> Buf;
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llvm::raw_svector_ostream Os(Buf);
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if (Capture.isExplicit()) {
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Os << "Captured ";
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} else {
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Os << "Implicitly captured ";
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}
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Os << "raw-pointer 'this' to ref-counted type or CheckedPtr-capable type "
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"is unsafe.";
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PathDiagnosticLocation BSLoc(Capture.getLocation(), BR->getSourceManager());
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auto Report = std::make_unique<BasicBugReport>(Bug, Os.str(), BSLoc);
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BR->emitReport(std::move(Report));
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}
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};
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} // namespace
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void ento::registerUncountedLambdaCapturesChecker(CheckerManager &Mgr) {
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Mgr.registerChecker<UncountedLambdaCapturesChecker>();
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}
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bool ento::shouldRegisterUncountedLambdaCapturesChecker(
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const CheckerManager &mgr) {
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return true;
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}
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