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351 lines
11 KiB
351 lines
11 KiB
//=- NSErrorChecker.cpp - Coding conventions for uses of NSError -*- 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 file defines a CheckNSError, a flow-insenstive check
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// that determines if an Objective-C class interface correctly returns
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// a non-void return type.
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//
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// File under feature request PR 2600.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
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#include "clang/AST/Decl.h"
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#include "clang/AST/DeclObjC.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/ProgramStateTrait.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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static bool IsNSError(QualType T, IdentifierInfo *II);
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static bool IsCFError(QualType T, IdentifierInfo *II);
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//===----------------------------------------------------------------------===//
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// NSErrorMethodChecker
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//===----------------------------------------------------------------------===//
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namespace {
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class NSErrorMethodChecker
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: public Checker< check::ASTDecl<ObjCMethodDecl> > {
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mutable IdentifierInfo *II;
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public:
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NSErrorMethodChecker() : II(nullptr) {}
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void checkASTDecl(const ObjCMethodDecl *D,
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AnalysisManager &mgr, BugReporter &BR) const;
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};
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}
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void NSErrorMethodChecker::checkASTDecl(const ObjCMethodDecl *D,
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AnalysisManager &mgr,
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BugReporter &BR) const {
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if (!D->isThisDeclarationADefinition())
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return;
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if (!D->getReturnType()->isVoidType())
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return;
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if (!II)
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II = &D->getASTContext().Idents.get("NSError");
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bool hasNSError = false;
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for (const auto *I : D->parameters()) {
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if (IsNSError(I->getType(), II)) {
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hasNSError = true;
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break;
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}
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}
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if (hasNSError) {
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const char *err = "Method accepting NSError** "
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"should have a non-void return value to indicate whether or not an "
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"error occurred";
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PathDiagnosticLocation L =
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PathDiagnosticLocation::create(D, BR.getSourceManager());
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BR.EmitBasicReport(D, this, "Bad return type when passing NSError**",
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"Coding conventions (Apple)", err, L);
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}
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}
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//===----------------------------------------------------------------------===//
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// CFErrorFunctionChecker
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//===----------------------------------------------------------------------===//
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namespace {
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class CFErrorFunctionChecker
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: public Checker< check::ASTDecl<FunctionDecl> > {
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mutable IdentifierInfo *II;
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public:
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CFErrorFunctionChecker() : II(nullptr) {}
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void checkASTDecl(const FunctionDecl *D,
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AnalysisManager &mgr, BugReporter &BR) const;
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};
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}
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static bool hasReservedReturnType(const FunctionDecl *D) {
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if (isa<CXXConstructorDecl>(D))
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return true;
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// operators delete and delete[] are required to have 'void' return type
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auto OperatorKind = D->getOverloadedOperator();
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return OperatorKind == OO_Delete || OperatorKind == OO_Array_Delete;
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}
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void CFErrorFunctionChecker::checkASTDecl(const FunctionDecl *D,
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AnalysisManager &mgr,
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BugReporter &BR) const {
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if (!D->doesThisDeclarationHaveABody())
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return;
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if (!D->getReturnType()->isVoidType())
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return;
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if (hasReservedReturnType(D))
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return;
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if (!II)
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II = &D->getASTContext().Idents.get("CFErrorRef");
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bool hasCFError = false;
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for (auto I : D->parameters()) {
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if (IsCFError(I->getType(), II)) {
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hasCFError = true;
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break;
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}
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}
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if (hasCFError) {
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const char *err = "Function accepting CFErrorRef* "
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"should have a non-void return value to indicate whether or not an "
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"error occurred";
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PathDiagnosticLocation L =
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PathDiagnosticLocation::create(D, BR.getSourceManager());
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BR.EmitBasicReport(D, this, "Bad return type when passing CFErrorRef*",
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"Coding conventions (Apple)", err, L);
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}
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}
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//===----------------------------------------------------------------------===//
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// NSOrCFErrorDerefChecker
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//===----------------------------------------------------------------------===//
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namespace {
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class NSErrorDerefBug : public BugType {
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public:
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NSErrorDerefBug(const CheckerNameRef Checker)
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: BugType(Checker, "NSError** null dereference",
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"Coding conventions (Apple)") {}
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};
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class CFErrorDerefBug : public BugType {
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public:
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CFErrorDerefBug(const CheckerNameRef Checker)
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: BugType(Checker, "CFErrorRef* null dereference",
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"Coding conventions (Apple)") {}
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};
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}
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namespace {
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class NSOrCFErrorDerefChecker
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: public Checker< check::Location,
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check::Event<ImplicitNullDerefEvent> > {
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mutable IdentifierInfo *NSErrorII, *CFErrorII;
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mutable std::unique_ptr<NSErrorDerefBug> NSBT;
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mutable std::unique_ptr<CFErrorDerefBug> CFBT;
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public:
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DefaultBool ShouldCheckNSError, ShouldCheckCFError;
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CheckerNameRef NSErrorName, CFErrorName;
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NSOrCFErrorDerefChecker() : NSErrorII(nullptr), CFErrorII(nullptr) {}
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void checkLocation(SVal loc, bool isLoad, const Stmt *S,
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CheckerContext &C) const;
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void checkEvent(ImplicitNullDerefEvent event) const;
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};
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}
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typedef llvm::ImmutableMap<SymbolRef, unsigned> ErrorOutFlag;
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REGISTER_TRAIT_WITH_PROGRAMSTATE(NSErrorOut, ErrorOutFlag)
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REGISTER_TRAIT_WITH_PROGRAMSTATE(CFErrorOut, ErrorOutFlag)
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template <typename T>
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static bool hasFlag(SVal val, ProgramStateRef state) {
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if (SymbolRef sym = val.getAsSymbol())
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if (const unsigned *attachedFlags = state->get<T>(sym))
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return *attachedFlags;
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return false;
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}
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template <typename T>
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static void setFlag(ProgramStateRef state, SVal val, CheckerContext &C) {
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// We tag the symbol that the SVal wraps.
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if (SymbolRef sym = val.getAsSymbol())
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C.addTransition(state->set<T>(sym, true));
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}
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static QualType parameterTypeFromSVal(SVal val, CheckerContext &C) {
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const StackFrameContext * SFC = C.getStackFrame();
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if (Optional<loc::MemRegionVal> X = val.getAs<loc::MemRegionVal>()) {
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const MemRegion* R = X->getRegion();
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if (const VarRegion *VR = R->getAs<VarRegion>())
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if (const StackArgumentsSpaceRegion *
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stackReg = dyn_cast<StackArgumentsSpaceRegion>(VR->getMemorySpace()))
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if (stackReg->getStackFrame() == SFC)
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return VR->getValueType();
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}
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return QualType();
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}
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void NSOrCFErrorDerefChecker::checkLocation(SVal loc, bool isLoad,
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const Stmt *S,
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CheckerContext &C) const {
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if (!isLoad)
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return;
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if (loc.isUndef() || !loc.getAs<Loc>())
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return;
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ASTContext &Ctx = C.getASTContext();
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ProgramStateRef state = C.getState();
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// If we are loading from NSError**/CFErrorRef* parameter, mark the resulting
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// SVal so that we can later check it when handling the
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// ImplicitNullDerefEvent event.
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// FIXME: Cumbersome! Maybe add hook at construction of SVals at start of
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// function ?
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QualType parmT = parameterTypeFromSVal(loc, C);
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if (parmT.isNull())
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return;
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if (!NSErrorII)
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NSErrorII = &Ctx.Idents.get("NSError");
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if (!CFErrorII)
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CFErrorII = &Ctx.Idents.get("CFErrorRef");
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if (ShouldCheckNSError && IsNSError(parmT, NSErrorII)) {
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setFlag<NSErrorOut>(state, state->getSVal(loc.castAs<Loc>()), C);
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return;
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}
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if (ShouldCheckCFError && IsCFError(parmT, CFErrorII)) {
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setFlag<CFErrorOut>(state, state->getSVal(loc.castAs<Loc>()), C);
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return;
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}
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}
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void NSOrCFErrorDerefChecker::checkEvent(ImplicitNullDerefEvent event) const {
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if (event.IsLoad)
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return;
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SVal loc = event.Location;
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ProgramStateRef state = event.SinkNode->getState();
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BugReporter &BR = *event.BR;
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bool isNSError = hasFlag<NSErrorOut>(loc, state);
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bool isCFError = false;
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if (!isNSError)
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isCFError = hasFlag<CFErrorOut>(loc, state);
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if (!(isNSError || isCFError))
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return;
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// Storing to possible null NSError/CFErrorRef out parameter.
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SmallString<128> Buf;
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llvm::raw_svector_ostream os(Buf);
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os << "Potential null dereference. According to coding standards ";
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os << (isNSError
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? "in 'Creating and Returning NSError Objects' the parameter"
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: "documented in CoreFoundation/CFError.h the parameter");
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os << " may be null";
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BugType *bug = nullptr;
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if (isNSError) {
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if (!NSBT)
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NSBT.reset(new NSErrorDerefBug(NSErrorName));
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bug = NSBT.get();
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}
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else {
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if (!CFBT)
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CFBT.reset(new CFErrorDerefBug(CFErrorName));
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bug = CFBT.get();
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}
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BR.emitReport(
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std::make_unique<PathSensitiveBugReport>(*bug, os.str(), event.SinkNode));
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}
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static bool IsNSError(QualType T, IdentifierInfo *II) {
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const PointerType* PPT = T->getAs<PointerType>();
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if (!PPT)
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return false;
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const ObjCObjectPointerType* PT =
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PPT->getPointeeType()->getAs<ObjCObjectPointerType>();
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if (!PT)
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return false;
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const ObjCInterfaceDecl *ID = PT->getInterfaceDecl();
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// FIXME: Can ID ever be NULL?
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if (ID)
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return II == ID->getIdentifier();
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return false;
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}
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static bool IsCFError(QualType T, IdentifierInfo *II) {
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const PointerType* PPT = T->getAs<PointerType>();
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if (!PPT) return false;
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const TypedefType* TT = PPT->getPointeeType()->getAs<TypedefType>();
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if (!TT) return false;
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return TT->getDecl()->getIdentifier() == II;
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}
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void ento::registerNSOrCFErrorDerefChecker(CheckerManager &mgr) {
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mgr.registerChecker<NSOrCFErrorDerefChecker>();
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}
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bool ento::shouldRegisterNSOrCFErrorDerefChecker(const CheckerManager &mgr) {
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return true;
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}
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void ento::registerNSErrorChecker(CheckerManager &mgr) {
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mgr.registerChecker<NSErrorMethodChecker>();
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NSOrCFErrorDerefChecker *checker = mgr.getChecker<NSOrCFErrorDerefChecker>();
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checker->ShouldCheckNSError = true;
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checker->NSErrorName = mgr.getCurrentCheckerName();
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}
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bool ento::shouldRegisterNSErrorChecker(const CheckerManager &mgr) {
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return true;
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}
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void ento::registerCFErrorChecker(CheckerManager &mgr) {
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mgr.registerChecker<CFErrorFunctionChecker>();
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NSOrCFErrorDerefChecker *checker = mgr.getChecker<NSOrCFErrorDerefChecker>();
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checker->ShouldCheckCFError = true;
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checker->CFErrorName = mgr.getCurrentCheckerName();
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}
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bool ento::shouldRegisterCFErrorChecker(const CheckerManager &mgr) {
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return true;
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}
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