1 //===- ObjCSuperDeallocChecker.cpp - Check correct use of [super dealloc] -===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This defines ObjCSuperDeallocChecker, a builtin check that warns when
11 // self is used after a call to [super dealloc] in MRR mode.
13 //===----------------------------------------------------------------------===//
15 #include "ClangSACheckers.h"
16 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
17 #include "clang/StaticAnalyzer/Core/Checker.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
19 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
21 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
23 using namespace clang;
27 class ObjCSuperDeallocChecker
28 : public Checker<check::PostObjCMessage, check::PreObjCMessage,
29 check::PreCall, check::Location> {
31 mutable IdentifierInfo *IIdealloc, *IINSObject;
32 mutable Selector SELdealloc;
34 std::unique_ptr<BugType> DoubleSuperDeallocBugType;
36 void initIdentifierInfoAndSelectors(ASTContext &Ctx) const;
38 bool isSuperDeallocMessage(const ObjCMethodCall &M) const;
41 ObjCSuperDeallocChecker();
42 void checkPostObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const;
43 void checkPreObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const;
45 void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
47 void checkLocation(SVal l, bool isLoad, const Stmt *S,
48 CheckerContext &C) const;
52 void diagnoseCallArguments(const CallEvent &CE, CheckerContext &C) const;
54 void reportUseAfterDealloc(SymbolRef Sym, StringRef Desc, const Stmt *S,
55 CheckerContext &C) const;
58 } // End anonymous namespace.
60 // Remember whether [super dealloc] has previously been called on the
61 // SymbolRef for the receiver.
62 REGISTER_SET_WITH_PROGRAMSTATE(CalledSuperDealloc, SymbolRef)
65 class SuperDeallocBRVisitor final : public BugReporterVisitor {
66 SymbolRef ReceiverSymbol;
70 SuperDeallocBRVisitor(SymbolRef ReceiverSymbol)
71 : ReceiverSymbol(ReceiverSymbol),
74 std::shared_ptr<PathDiagnosticPiece> VisitNode(const ExplodedNode *Succ,
75 const ExplodedNode *Pred,
76 BugReporterContext &BRC,
77 BugReport &BR) override;
79 void Profile(llvm::FoldingSetNodeID &ID) const override {
80 ID.Add(ReceiverSymbol);
83 } // End anonymous namespace.
85 void ObjCSuperDeallocChecker::checkPreObjCMessage(const ObjCMethodCall &M,
86 CheckerContext &C) const {
88 ProgramStateRef State = C.getState();
89 SymbolRef ReceiverSymbol = M.getReceiverSVal().getAsSymbol();
90 if (!ReceiverSymbol) {
91 diagnoseCallArguments(M, C);
95 bool AlreadyCalled = State->contains<CalledSuperDealloc>(ReceiverSymbol);
101 if (isSuperDeallocMessage(M)) {
102 Desc = "[super dealloc] should not be called multiple times";
107 reportUseAfterDealloc(ReceiverSymbol, Desc, M.getOriginExpr(), C);
110 void ObjCSuperDeallocChecker::checkPreCall(const CallEvent &Call,
111 CheckerContext &C) const {
112 diagnoseCallArguments(Call, C);
115 void ObjCSuperDeallocChecker::checkPostObjCMessage(const ObjCMethodCall &M,
116 CheckerContext &C) const {
117 // Check for [super dealloc] method call.
118 if (!isSuperDeallocMessage(M))
121 ProgramStateRef State = C.getState();
122 SymbolRef ReceiverSymbol = M.getSelfSVal().getAsSymbol();
123 assert(ReceiverSymbol && "No receiver symbol at call to [super dealloc]?");
125 // We add this transition in checkPostObjCMessage to avoid warning when
126 // we inline a call to [super dealloc] where the inlined call itself
127 // calls [super dealloc].
128 State = State->add<CalledSuperDealloc>(ReceiverSymbol);
129 C.addTransition(State);
132 void ObjCSuperDeallocChecker::checkLocation(SVal L, bool IsLoad, const Stmt *S,
133 CheckerContext &C) const {
134 SymbolRef BaseSym = L.getLocSymbolInBase();
138 ProgramStateRef State = C.getState();
140 if (!State->contains<CalledSuperDealloc>(BaseSym))
143 const MemRegion *R = L.getAsRegion();
147 // Climb the super regions to find the base symbol while recording
148 // the second-to-last region for error reporting.
149 const MemRegion *PriorSubRegion = nullptr;
150 while (const SubRegion *SR = dyn_cast<SubRegion>(R)) {
151 if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(SR)) {
152 BaseSym = SymR->getSymbol();
155 R = SR->getSuperRegion();
160 StringRef Desc = StringRef();
161 auto *IvarRegion = dyn_cast_or_null<ObjCIvarRegion>(PriorSubRegion);
164 llvm::raw_string_ostream OS(Buf);
166 OS << "Use of instance variable '" << *IvarRegion->getDecl() <<
167 "' after 'self' has been deallocated";
171 reportUseAfterDealloc(BaseSym, Desc, S, C);
174 /// Report a use-after-dealloc on Sym. If not empty,
175 /// Desc will be used to describe the error; otherwise,
176 /// a default warning will be used.
177 void ObjCSuperDeallocChecker::reportUseAfterDealloc(SymbolRef Sym,
180 CheckerContext &C) const {
181 // We have a use of self after free.
182 // This likely causes a crash, so stop exploring the
183 // path by generating a sink.
184 ExplodedNode *ErrNode = C.generateErrorNode();
185 // If we've already reached this node on another path, return.
190 Desc = "Use of 'self' after it has been deallocated";
192 // Generate the report.
193 std::unique_ptr<BugReport> BR(
194 new BugReport(*DoubleSuperDeallocBugType, Desc, ErrNode));
195 BR->addRange(S->getSourceRange());
196 BR->addVisitor(llvm::make_unique<SuperDeallocBRVisitor>(Sym));
197 C.emitReport(std::move(BR));
200 /// Diagnose if any of the arguments to CE have already been
202 void ObjCSuperDeallocChecker::diagnoseCallArguments(const CallEvent &CE,
203 CheckerContext &C) const {
204 ProgramStateRef State = C.getState();
205 unsigned ArgCount = CE.getNumArgs();
206 for (unsigned I = 0; I < ArgCount; I++) {
207 SymbolRef Sym = CE.getArgSVal(I).getAsSymbol();
211 if (State->contains<CalledSuperDealloc>(Sym)) {
212 reportUseAfterDealloc(Sym, StringRef(), CE.getArgExpr(I), C);
218 ObjCSuperDeallocChecker::ObjCSuperDeallocChecker()
219 : IIdealloc(nullptr), IINSObject(nullptr) {
221 DoubleSuperDeallocBugType.reset(
222 new BugType(this, "[super dealloc] should not be called more than once",
223 categories::CoreFoundationObjectiveC));
227 ObjCSuperDeallocChecker::initIdentifierInfoAndSelectors(ASTContext &Ctx) const {
231 IIdealloc = &Ctx.Idents.get("dealloc");
232 IINSObject = &Ctx.Idents.get("NSObject");
234 SELdealloc = Ctx.Selectors.getSelector(0, &IIdealloc);
238 ObjCSuperDeallocChecker::isSuperDeallocMessage(const ObjCMethodCall &M) const {
239 if (M.getOriginExpr()->getReceiverKind() != ObjCMessageExpr::SuperInstance)
242 ASTContext &Ctx = M.getState()->getStateManager().getContext();
243 initIdentifierInfoAndSelectors(Ctx);
245 return M.getSelector() == SELdealloc;
248 std::shared_ptr<PathDiagnosticPiece>
249 SuperDeallocBRVisitor::VisitNode(const ExplodedNode *Succ,
250 const ExplodedNode *Pred,
251 BugReporterContext &BRC, BugReport &BR) {
255 ProgramStateRef State = Succ->getState();
258 Succ->getState()->contains<CalledSuperDealloc>(ReceiverSymbol);
260 Pred->getState()->contains<CalledSuperDealloc>(ReceiverSymbol);
262 // Is Succ the node on which the analyzer noted that [super dealloc] was
263 // called on ReceiverSymbol?
264 if (CalledNow && !CalledBefore) {
267 ProgramPoint P = Succ->getLocation();
268 PathDiagnosticLocation L =
269 PathDiagnosticLocation::create(P, BRC.getSourceManager());
271 if (!L.isValid() || !L.asLocation().isValid())
274 return std::make_shared<PathDiagnosticEventPiece>(
275 L, "[super dealloc] called here");
281 //===----------------------------------------------------------------------===//
282 // Checker Registration.
283 //===----------------------------------------------------------------------===//
285 void ento::registerObjCSuperDeallocChecker(CheckerManager &Mgr) {
286 const LangOptions &LangOpts = Mgr.getLangOpts();
287 if (LangOpts.getGC() == LangOptions::GCOnly || LangOpts.ObjCAutoRefCount)
289 Mgr.registerChecker<ObjCSuperDeallocChecker>();