1 //===--- CallAndMessageChecker.cpp ------------------------------*- C++ -*--==//
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 CallAndMessageChecker, a builtin checker that checks for various
11 // errors of call and objc message expressions.
13 //===----------------------------------------------------------------------===//
15 #include "ClangSACheckers.h"
16 #include "clang/AST/ParentMap.h"
17 #include "clang/Basic/TargetInfo.h"
18 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
19 #include "clang/StaticAnalyzer/Core/Checker.h"
20 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
21 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
22 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
23 #include "llvm/ADT/SmallString.h"
24 #include "llvm/Support/raw_ostream.h"
26 using namespace clang;
30 class CallAndMessageChecker
31 : public Checker< check::PreStmt<CallExpr>,
32 check::PreStmt<CXXDeleteExpr>,
33 check::PreObjCMessage,
35 mutable OwningPtr<BugType> BT_call_null;
36 mutable OwningPtr<BugType> BT_call_undef;
37 mutable OwningPtr<BugType> BT_cxx_call_null;
38 mutable OwningPtr<BugType> BT_cxx_call_undef;
39 mutable OwningPtr<BugType> BT_call_arg;
40 mutable OwningPtr<BugType> BT_cxx_delete_undef;
41 mutable OwningPtr<BugType> BT_msg_undef;
42 mutable OwningPtr<BugType> BT_objc_prop_undef;
43 mutable OwningPtr<BugType> BT_objc_subscript_undef;
44 mutable OwningPtr<BugType> BT_msg_arg;
45 mutable OwningPtr<BugType> BT_msg_ret;
46 mutable OwningPtr<BugType> BT_call_few_args;
49 void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
50 void checkPreStmt(const CXXDeleteExpr *DE, CheckerContext &C) const;
51 void checkPreObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;
52 void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
55 static bool PreVisitProcessArg(CheckerContext &C, SVal V,
56 SourceRange argRange, const Expr *argEx,
57 bool IsFirstArgument, bool checkUninitFields,
58 const CallEvent &Call, OwningPtr<BugType> &BT);
60 static void emitBadCall(BugType *BT, CheckerContext &C, const Expr *BadE);
61 void emitNilReceiverBug(CheckerContext &C, const ObjCMethodCall &msg,
62 ExplodedNode *N) const;
64 void HandleNilReceiver(CheckerContext &C,
65 ProgramStateRef state,
66 const ObjCMethodCall &msg) const;
68 static void LazyInit_BT(const char *desc, OwningPtr<BugType> &BT) {
70 BT.reset(new BuiltinBug(desc));
73 } // end anonymous namespace
75 void CallAndMessageChecker::emitBadCall(BugType *BT, CheckerContext &C,
77 ExplodedNode *N = C.generateSink();
81 BugReport *R = new BugReport(*BT, BT->getName(), N);
83 R->addRange(BadE->getSourceRange());
84 if (BadE->isGLValue())
85 BadE = bugreporter::getDerefExpr(BadE);
86 bugreporter::trackNullOrUndefValue(N, BadE, *R);
91 static StringRef describeUninitializedArgumentInCall(const CallEvent &Call,
92 bool IsFirstArgument) {
93 switch (Call.getKind()) {
94 case CE_ObjCMessage: {
95 const ObjCMethodCall &Msg = cast<ObjCMethodCall>(Call);
96 switch (Msg.getMessageKind()) {
98 return "Argument in message expression is an uninitialized value";
99 case OCM_PropertyAccess:
100 assert(Msg.isSetter() && "Getters have no args");
101 return "Argument for property setter is an uninitialized value";
103 if (Msg.isSetter() && IsFirstArgument)
104 return "Argument for subscript setter is an uninitialized value";
105 return "Subscript index is an uninitialized value";
107 llvm_unreachable("Unknown message kind.");
110 return "Block call argument is an uninitialized value";
112 return "Function call argument is an uninitialized value";
116 bool CallAndMessageChecker::PreVisitProcessArg(CheckerContext &C,
117 SVal V, SourceRange argRange,
119 bool IsFirstArgument,
120 bool checkUninitFields,
121 const CallEvent &Call,
122 OwningPtr<BugType> &BT) {
124 if (ExplodedNode *N = C.generateSink()) {
125 LazyInit_BT("Uninitialized argument value", BT);
127 // Generate a report for this bug.
128 StringRef Desc = describeUninitializedArgumentInCall(Call,
130 BugReport *R = new BugReport(*BT, Desc, N);
131 R->addRange(argRange);
133 bugreporter::trackNullOrUndefValue(N, argEx, *R);
139 if (!checkUninitFields)
142 if (Optional<nonloc::LazyCompoundVal> LV =
143 V.getAs<nonloc::LazyCompoundVal>()) {
145 class FindUninitializedField {
147 SmallVector<const FieldDecl *, 10> FieldChain;
149 StoreManager &StoreMgr;
150 MemRegionManager &MrMgr;
153 FindUninitializedField(StoreManager &storeMgr,
154 MemRegionManager &mrMgr, Store s)
155 : StoreMgr(storeMgr), MrMgr(mrMgr), store(s) {}
157 bool Find(const TypedValueRegion *R) {
158 QualType T = R->getValueType();
159 if (const RecordType *RT = T->getAsStructureType()) {
160 const RecordDecl *RD = RT->getDecl()->getDefinition();
161 assert(RD && "Referred record has no definition");
162 for (RecordDecl::field_iterator I =
163 RD->field_begin(), E = RD->field_end(); I!=E; ++I) {
164 const FieldRegion *FR = MrMgr.getFieldRegion(*I, R);
165 FieldChain.push_back(*I);
167 if (T->getAsStructureType()) {
172 const SVal &V = StoreMgr.getBinding(store, loc::MemRegionVal(FR));
176 FieldChain.pop_back();
184 const LazyCompoundValData *D = LV->getCVData();
185 FindUninitializedField F(C.getState()->getStateManager().getStoreManager(),
186 C.getSValBuilder().getRegionManager(),
189 if (F.Find(D->getRegion())) {
190 if (ExplodedNode *N = C.generateSink()) {
191 LazyInit_BT("Uninitialized argument value", BT);
192 SmallString<512> Str;
193 llvm::raw_svector_ostream os(Str);
194 os << "Passed-by-value struct argument contains uninitialized data";
196 if (F.FieldChain.size() == 1)
197 os << " (e.g., field: '" << *F.FieldChain[0] << "')";
199 os << " (e.g., via the field chain: '";
201 for (SmallVectorImpl<const FieldDecl *>::iterator
202 DI = F.FieldChain.begin(), DE = F.FieldChain.end(); DI!=DE;++DI){
212 // Generate a report for this bug.
213 BugReport *R = new BugReport(*BT, os.str(), N);
214 R->addRange(argRange);
216 // FIXME: enhance track back for uninitialized value for arbitrary
227 void CallAndMessageChecker::checkPreStmt(const CallExpr *CE,
228 CheckerContext &C) const{
230 const Expr *Callee = CE->getCallee()->IgnoreParens();
231 ProgramStateRef State = C.getState();
232 const LocationContext *LCtx = C.getLocationContext();
233 SVal L = State->getSVal(Callee, LCtx);
237 BT_call_undef.reset(new BuiltinBug("Called function pointer is an "
238 "uninitalized pointer value"));
239 emitBadCall(BT_call_undef.get(), C, Callee);
243 ProgramStateRef StNonNull, StNull;
244 llvm::tie(StNonNull, StNull) =
245 State->assume(L.castAs<DefinedOrUnknownSVal>());
247 if (StNull && !StNonNull) {
250 new BuiltinBug("Called function pointer is null (null dereference)"));
251 emitBadCall(BT_call_null.get(), C, Callee);
255 C.addTransition(StNonNull);
258 void CallAndMessageChecker::checkPreStmt(const CXXDeleteExpr *DE,
259 CheckerContext &C) const {
261 SVal Arg = C.getSVal(DE->getArgument());
264 ExplodedNode *N = C.generateSink();
267 if (!BT_cxx_delete_undef)
268 BT_cxx_delete_undef.reset(new BuiltinBug("Uninitialized argument value"));
269 if (DE->isArrayFormAsWritten())
270 Desc = "Argument to 'delete[]' is uninitialized";
272 Desc = "Argument to 'delete' is uninitialized";
273 BugType *BT = BT_cxx_delete_undef.get();
274 BugReport *R = new BugReport(*BT, Desc, N);
275 bugreporter::trackNullOrUndefValue(N, DE, *R);
282 void CallAndMessageChecker::checkPreCall(const CallEvent &Call,
283 CheckerContext &C) const {
284 ProgramStateRef State = C.getState();
286 // If this is a call to a C++ method, check if the callee is null or
288 if (const CXXInstanceCall *CC = dyn_cast<CXXInstanceCall>(&Call)) {
289 SVal V = CC->getCXXThisVal();
291 if (!BT_cxx_call_undef)
292 BT_cxx_call_undef.reset(new BuiltinBug("Called C++ object pointer is "
294 emitBadCall(BT_cxx_call_undef.get(), C, CC->getCXXThisExpr());
298 ProgramStateRef StNonNull, StNull;
299 llvm::tie(StNonNull, StNull) =
300 State->assume(V.castAs<DefinedOrUnknownSVal>());
302 if (StNull && !StNonNull) {
303 if (!BT_cxx_call_null)
304 BT_cxx_call_null.reset(new BuiltinBug("Called C++ object pointer "
306 emitBadCall(BT_cxx_call_null.get(), C, CC->getCXXThisExpr());
313 const Decl *D = Call.getDecl();
314 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {
315 // If we have a declaration, we can make sure we pass enough parameters to
317 unsigned Params = FD->getNumParams();
318 if (Call.getNumArgs() < Params) {
319 ExplodedNode *N = C.generateSink();
323 LazyInit_BT("Function call with too few arguments", BT_call_few_args);
325 SmallString<512> Str;
326 llvm::raw_svector_ostream os(Str);
327 os << "Function taking " << Params << " argument"
328 << (Params == 1 ? "" : "s") << " is called with less ("
329 << Call.getNumArgs() << ")";
331 BugReport *R = new BugReport(*BT_call_few_args, os.str(), N);
336 // Don't check for uninitialized field values in arguments if the
337 // caller has a body that is available and we have the chance to inline it.
338 // This is a hack, but is a reasonable compromise betweens sometimes warning
339 // and sometimes not depending on if we decide to inline a function.
340 const bool checkUninitFields =
341 !(C.getAnalysisManager().shouldInlineCall() && (D && D->getBody()));
343 OwningPtr<BugType> *BT;
344 if (isa<ObjCMethodCall>(Call))
349 for (unsigned i = 0, e = Call.getNumArgs(); i != e; ++i)
350 if (PreVisitProcessArg(C, Call.getArgSVal(i), Call.getArgSourceRange(i),
351 Call.getArgExpr(i), /*IsFirstArgument=*/i == 0,
352 checkUninitFields, Call, *BT))
355 // If we make it here, record our assumptions about the callee.
356 C.addTransition(State);
359 void CallAndMessageChecker::checkPreObjCMessage(const ObjCMethodCall &msg,
360 CheckerContext &C) const {
361 SVal recVal = msg.getReceiverSVal();
362 if (recVal.isUndef()) {
363 if (ExplodedNode *N = C.generateSink()) {
365 switch (msg.getMessageKind()) {
368 BT_msg_undef.reset(new BuiltinBug("Receiver in message expression "
369 "is an uninitialized value"));
370 BT = BT_msg_undef.get();
372 case OCM_PropertyAccess:
373 if (!BT_objc_prop_undef)
374 BT_objc_prop_undef.reset(new BuiltinBug("Property access on an "
375 "uninitialized object "
377 BT = BT_objc_prop_undef.get();
380 if (!BT_objc_subscript_undef)
381 BT_objc_subscript_undef.reset(new BuiltinBug("Subscript access on an "
382 "uninitialized object "
384 BT = BT_objc_subscript_undef.get();
387 assert(BT && "Unknown message kind.");
389 BugReport *R = new BugReport(*BT, BT->getName(), N);
390 const ObjCMessageExpr *ME = msg.getOriginExpr();
391 R->addRange(ME->getReceiverRange());
393 // FIXME: getTrackNullOrUndefValueVisitor can't handle "super" yet.
394 if (const Expr *ReceiverE = ME->getInstanceReceiver())
395 bugreporter::trackNullOrUndefValue(N, ReceiverE, *R);
400 // Bifurcate the state into nil and non-nil ones.
401 DefinedOrUnknownSVal receiverVal = recVal.castAs<DefinedOrUnknownSVal>();
403 ProgramStateRef state = C.getState();
404 ProgramStateRef notNilState, nilState;
405 llvm::tie(notNilState, nilState) = state->assume(receiverVal);
407 // Handle receiver must be nil.
408 if (nilState && !notNilState) {
409 HandleNilReceiver(C, state, msg);
415 void CallAndMessageChecker::emitNilReceiverBug(CheckerContext &C,
416 const ObjCMethodCall &msg,
417 ExplodedNode *N) const {
421 new BuiltinBug("Receiver in message expression is 'nil'"));
423 const ObjCMessageExpr *ME = msg.getOriginExpr();
425 QualType ResTy = msg.getResultType();
427 SmallString<200> buf;
428 llvm::raw_svector_ostream os(buf);
429 os << "The receiver of message '" << ME->getSelector().getAsString()
431 if (ResTy->isReferenceType()) {
432 os << ", which results in forming a null reference";
434 os << " and returns a value of type '";
435 msg.getResultType().print(os, C.getLangOpts());
436 os << "' that will be garbage";
439 BugReport *report = new BugReport(*BT_msg_ret, os.str(), N);
440 report->addRange(ME->getReceiverRange());
441 // FIXME: This won't track "self" in messages to super.
442 if (const Expr *receiver = ME->getInstanceReceiver()) {
443 bugreporter::trackNullOrUndefValue(N, receiver, *report);
445 C.emitReport(report);
448 static bool supportsNilWithFloatRet(const llvm::Triple &triple) {
449 return (triple.getVendor() == llvm::Triple::Apple &&
450 (triple.isiOS() || !triple.isMacOSXVersionLT(10,5)));
453 void CallAndMessageChecker::HandleNilReceiver(CheckerContext &C,
454 ProgramStateRef state,
455 const ObjCMethodCall &Msg) const {
456 ASTContext &Ctx = C.getASTContext();
457 static SimpleProgramPointTag Tag("CallAndMessageChecker : NilReceiver");
459 // Check the return type of the message expression. A message to nil will
460 // return different values depending on the return type and the architecture.
461 QualType RetTy = Msg.getResultType();
462 CanQualType CanRetTy = Ctx.getCanonicalType(RetTy);
463 const LocationContext *LCtx = C.getLocationContext();
465 if (CanRetTy->isStructureOrClassType()) {
466 // Structure returns are safe since the compiler zeroes them out.
467 SVal V = C.getSValBuilder().makeZeroVal(RetTy);
468 C.addTransition(state->BindExpr(Msg.getOriginExpr(), LCtx, V), &Tag);
472 // Other cases: check if sizeof(return type) > sizeof(void*)
473 if (CanRetTy != Ctx.VoidTy && C.getLocationContext()->getParentMap()
474 .isConsumedExpr(Msg.getOriginExpr())) {
475 // Compute: sizeof(void *) and sizeof(return type)
476 const uint64_t voidPtrSize = Ctx.getTypeSize(Ctx.VoidPtrTy);
477 const uint64_t returnTypeSize = Ctx.getTypeSize(CanRetTy);
479 if (CanRetTy.getTypePtr()->isReferenceType()||
480 (voidPtrSize < returnTypeSize &&
481 !(supportsNilWithFloatRet(Ctx.getTargetInfo().getTriple()) &&
482 (Ctx.FloatTy == CanRetTy ||
483 Ctx.DoubleTy == CanRetTy ||
484 Ctx.LongDoubleTy == CanRetTy ||
485 Ctx.LongLongTy == CanRetTy ||
486 Ctx.UnsignedLongLongTy == CanRetTy)))) {
487 if (ExplodedNode *N = C.generateSink(state, 0 , &Tag))
488 emitNilReceiverBug(C, Msg, N);
492 // Handle the safe cases where the return value is 0 if the
495 // FIXME: For now take the conservative approach that we only
496 // return null values if we *know* that the receiver is nil.
497 // This is because we can have surprises like:
499 // ... = [[NSScreens screens] objectAtIndex:0];
501 // What can happen is that [... screens] could return nil, but
502 // it most likely isn't nil. We should assume the semantics
503 // of this case unless we have *a lot* more knowledge.
505 SVal V = C.getSValBuilder().makeZeroVal(RetTy);
506 C.addTransition(state->BindExpr(Msg.getOriginExpr(), LCtx, V), &Tag);
510 C.addTransition(state);
513 void ento::registerCallAndMessageChecker(CheckerManager &mgr) {
514 mgr.registerChecker<CallAndMessageChecker>();