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;
32 DefaultBool Check_CallAndMessageUnInitRefArg;
33 DefaultBool Check_CallAndMessageChecker;
35 CheckName CheckName_CallAndMessageUnInitRefArg;
36 CheckName CheckName_CallAndMessageChecker;
39 class CallAndMessageChecker
40 : public Checker< check::PreStmt<CallExpr>,
41 check::PreStmt<CXXDeleteExpr>,
42 check::PreObjCMessage,
43 check::ObjCMessageNil,
45 mutable std::unique_ptr<BugType> BT_call_null;
46 mutable std::unique_ptr<BugType> BT_call_undef;
47 mutable std::unique_ptr<BugType> BT_cxx_call_null;
48 mutable std::unique_ptr<BugType> BT_cxx_call_undef;
49 mutable std::unique_ptr<BugType> BT_call_arg;
50 mutable std::unique_ptr<BugType> BT_cxx_delete_undef;
51 mutable std::unique_ptr<BugType> BT_msg_undef;
52 mutable std::unique_ptr<BugType> BT_objc_prop_undef;
53 mutable std::unique_ptr<BugType> BT_objc_subscript_undef;
54 mutable std::unique_ptr<BugType> BT_msg_arg;
55 mutable std::unique_ptr<BugType> BT_msg_ret;
56 mutable std::unique_ptr<BugType> BT_call_few_args;
61 void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
62 void checkPreStmt(const CXXDeleteExpr *DE, CheckerContext &C) const;
63 void checkPreObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;
65 /// Fill in the return value that results from messaging nil based on the
66 /// return type and architecture and diagnose if the return value will be
68 void checkObjCMessageNil(const ObjCMethodCall &msg, CheckerContext &C) const;
70 void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
73 bool PreVisitProcessArg(CheckerContext &C, SVal V, SourceRange ArgRange,
74 const Expr *ArgEx, bool IsFirstArgument,
75 bool CheckUninitFields, const CallEvent &Call,
76 std::unique_ptr<BugType> &BT,
77 const ParmVarDecl *ParamDecl) const;
79 static void emitBadCall(BugType *BT, CheckerContext &C, const Expr *BadE);
80 void emitNilReceiverBug(CheckerContext &C, const ObjCMethodCall &msg,
81 ExplodedNode *N) const;
83 void HandleNilReceiver(CheckerContext &C,
84 ProgramStateRef state,
85 const ObjCMethodCall &msg) const;
87 void LazyInit_BT(const char *desc, std::unique_ptr<BugType> &BT) const {
89 BT.reset(new BuiltinBug(this, desc));
91 bool uninitRefOrPointer(CheckerContext &C, const SVal &V,
93 const Expr *ArgEx, std::unique_ptr<BugType> &BT,
94 const ParmVarDecl *ParamDecl, const char *BD) const;
96 } // end anonymous namespace
98 void CallAndMessageChecker::emitBadCall(BugType *BT, CheckerContext &C,
100 ExplodedNode *N = C.generateErrorNode();
104 auto R = llvm::make_unique<BugReport>(*BT, BT->getName(), N);
106 R->addRange(BadE->getSourceRange());
107 if (BadE->isGLValue())
108 BadE = bugreporter::getDerefExpr(BadE);
109 bugreporter::trackNullOrUndefValue(N, BadE, *R);
111 C.emitReport(std::move(R));
114 static StringRef describeUninitializedArgumentInCall(const CallEvent &Call,
115 bool IsFirstArgument) {
116 switch (Call.getKind()) {
117 case CE_ObjCMessage: {
118 const ObjCMethodCall &Msg = cast<ObjCMethodCall>(Call);
119 switch (Msg.getMessageKind()) {
121 return "Argument in message expression is an uninitialized value";
122 case OCM_PropertyAccess:
123 assert(Msg.isSetter() && "Getters have no args");
124 return "Argument for property setter is an uninitialized value";
126 if (Msg.isSetter() && IsFirstArgument)
127 return "Argument for subscript setter is an uninitialized value";
128 return "Subscript index is an uninitialized value";
130 llvm_unreachable("Unknown message kind.");
133 return "Block call argument is an uninitialized value";
135 return "Function call argument is an uninitialized value";
139 bool CallAndMessageChecker::uninitRefOrPointer(CheckerContext &C,
141 SourceRange ArgRange,
143 std::unique_ptr<BugType> &BT,
144 const ParmVarDecl *ParamDecl,
145 const char *BD) const {
146 if (!Filter.Check_CallAndMessageUnInitRefArg)
149 // No parameter declaration available, i.e. variadic function argument.
153 // If parameter is declared as pointer to const in function declaration,
154 // then check if corresponding argument in function call is
155 // pointing to undefined symbol value (uninitialized memory).
158 if (ParamDecl->getType()->isPointerType()) {
159 Message = "Function call argument is a pointer to uninitialized value";
160 } else if (ParamDecl->getType()->isReferenceType()) {
161 Message = "Function call argument is an uninitialized value";
165 if(!ParamDecl->getType()->getPointeeType().isConstQualified())
168 if (const MemRegion *SValMemRegion = V.getAsRegion()) {
169 const ProgramStateRef State = C.getState();
170 const SVal PSV = State->getSVal(SValMemRegion);
172 if (ExplodedNode *N = C.generateErrorNode()) {
174 auto R = llvm::make_unique<BugReport>(*BT, Message, N);
175 R->addRange(ArgRange);
177 bugreporter::trackNullOrUndefValue(N, ArgEx, *R);
179 C.emitReport(std::move(R));
187 bool CallAndMessageChecker::PreVisitProcessArg(CheckerContext &C,
189 SourceRange ArgRange,
191 bool IsFirstArgument,
192 bool CheckUninitFields,
193 const CallEvent &Call,
194 std::unique_ptr<BugType> &BT,
195 const ParmVarDecl *ParamDecl
197 const char *BD = "Uninitialized argument value";
199 if (uninitRefOrPointer(C, V, ArgRange, ArgEx, BT, ParamDecl, BD))
203 if (ExplodedNode *N = C.generateErrorNode()) {
206 // Generate a report for this bug.
208 describeUninitializedArgumentInCall(Call, IsFirstArgument);
209 auto R = llvm::make_unique<BugReport>(*BT, Desc, N);
210 R->addRange(ArgRange);
212 bugreporter::trackNullOrUndefValue(N, ArgEx, *R);
213 C.emitReport(std::move(R));
218 if (!CheckUninitFields)
221 if (Optional<nonloc::LazyCompoundVal> LV =
222 V.getAs<nonloc::LazyCompoundVal>()) {
224 class FindUninitializedField {
226 SmallVector<const FieldDecl *, 10> FieldChain;
228 StoreManager &StoreMgr;
229 MemRegionManager &MrMgr;
232 FindUninitializedField(StoreManager &storeMgr,
233 MemRegionManager &mrMgr, Store s)
234 : StoreMgr(storeMgr), MrMgr(mrMgr), store(s) {}
236 bool Find(const TypedValueRegion *R) {
237 QualType T = R->getValueType();
238 if (const RecordType *RT = T->getAsStructureType()) {
239 const RecordDecl *RD = RT->getDecl()->getDefinition();
240 assert(RD && "Referred record has no definition");
241 for (const auto *I : RD->fields()) {
242 const FieldRegion *FR = MrMgr.getFieldRegion(I, R);
243 FieldChain.push_back(I);
245 if (T->getAsStructureType()) {
250 const SVal &V = StoreMgr.getBinding(store, loc::MemRegionVal(FR));
254 FieldChain.pop_back();
262 const LazyCompoundValData *D = LV->getCVData();
263 FindUninitializedField F(C.getState()->getStateManager().getStoreManager(),
264 C.getSValBuilder().getRegionManager(),
267 if (F.Find(D->getRegion())) {
268 if (ExplodedNode *N = C.generateErrorNode()) {
270 SmallString<512> Str;
271 llvm::raw_svector_ostream os(Str);
272 os << "Passed-by-value struct argument contains uninitialized data";
274 if (F.FieldChain.size() == 1)
275 os << " (e.g., field: '" << *F.FieldChain[0] << "')";
277 os << " (e.g., via the field chain: '";
279 for (SmallVectorImpl<const FieldDecl *>::iterator
280 DI = F.FieldChain.begin(), DE = F.FieldChain.end(); DI!=DE;++DI){
290 // Generate a report for this bug.
291 auto R = llvm::make_unique<BugReport>(*BT, os.str(), N);
292 R->addRange(ArgRange);
294 // FIXME: enhance track back for uninitialized value for arbitrary
296 C.emitReport(std::move(R));
305 void CallAndMessageChecker::checkPreStmt(const CallExpr *CE,
306 CheckerContext &C) const{
308 const Expr *Callee = CE->getCallee()->IgnoreParens();
309 ProgramStateRef State = C.getState();
310 const LocationContext *LCtx = C.getLocationContext();
311 SVal L = State->getSVal(Callee, LCtx);
315 BT_call_undef.reset(new BuiltinBug(
316 this, "Called function pointer is an uninitalized pointer value"));
317 emitBadCall(BT_call_undef.get(), C, Callee);
321 ProgramStateRef StNonNull, StNull;
322 std::tie(StNonNull, StNull) = State->assume(L.castAs<DefinedOrUnknownSVal>());
324 if (StNull && !StNonNull) {
326 BT_call_null.reset(new BuiltinBug(
327 this, "Called function pointer is null (null dereference)"));
328 emitBadCall(BT_call_null.get(), C, Callee);
332 C.addTransition(StNonNull);
335 void CallAndMessageChecker::checkPreStmt(const CXXDeleteExpr *DE,
336 CheckerContext &C) const {
338 SVal Arg = C.getSVal(DE->getArgument());
341 ExplodedNode *N = C.generateErrorNode();
344 if (!BT_cxx_delete_undef)
345 BT_cxx_delete_undef.reset(
346 new BuiltinBug(this, "Uninitialized argument value"));
347 if (DE->isArrayFormAsWritten())
348 Desc = "Argument to 'delete[]' is uninitialized";
350 Desc = "Argument to 'delete' is uninitialized";
351 BugType *BT = BT_cxx_delete_undef.get();
352 auto R = llvm::make_unique<BugReport>(*BT, Desc, N);
353 bugreporter::trackNullOrUndefValue(N, DE, *R);
354 C.emitReport(std::move(R));
360 void CallAndMessageChecker::checkPreCall(const CallEvent &Call,
361 CheckerContext &C) const {
362 ProgramStateRef State = C.getState();
364 // If this is a call to a C++ method, check if the callee is null or
366 if (const CXXInstanceCall *CC = dyn_cast<CXXInstanceCall>(&Call)) {
367 SVal V = CC->getCXXThisVal();
369 if (!BT_cxx_call_undef)
370 BT_cxx_call_undef.reset(
371 new BuiltinBug(this, "Called C++ object pointer is uninitialized"));
372 emitBadCall(BT_cxx_call_undef.get(), C, CC->getCXXThisExpr());
376 ProgramStateRef StNonNull, StNull;
377 std::tie(StNonNull, StNull) =
378 State->assume(V.castAs<DefinedOrUnknownSVal>());
380 if (StNull && !StNonNull) {
381 if (!BT_cxx_call_null)
382 BT_cxx_call_null.reset(
383 new BuiltinBug(this, "Called C++ object pointer is null"));
384 emitBadCall(BT_cxx_call_null.get(), C, CC->getCXXThisExpr());
391 const Decl *D = Call.getDecl();
392 const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D);
394 // If we have a declaration, we can make sure we pass enough parameters to
396 unsigned Params = FD->getNumParams();
397 if (Call.getNumArgs() < Params) {
398 ExplodedNode *N = C.generateErrorNode();
402 LazyInit_BT("Function call with too few arguments", BT_call_few_args);
404 SmallString<512> Str;
405 llvm::raw_svector_ostream os(Str);
406 os << "Function taking " << Params << " argument"
407 << (Params == 1 ? "" : "s") << " is called with less ("
408 << Call.getNumArgs() << ")";
411 llvm::make_unique<BugReport>(*BT_call_few_args, os.str(), N));
415 // Don't check for uninitialized field values in arguments if the
416 // caller has a body that is available and we have the chance to inline it.
417 // This is a hack, but is a reasonable compromise betweens sometimes warning
418 // and sometimes not depending on if we decide to inline a function.
419 const bool checkUninitFields =
420 !(C.getAnalysisManager().shouldInlineCall() && (D && D->getBody()));
422 std::unique_ptr<BugType> *BT;
423 if (isa<ObjCMethodCall>(Call))
428 for (unsigned i = 0, e = Call.getNumArgs(); i != e; ++i) {
429 const ParmVarDecl *ParamDecl = nullptr;
430 if(FD && i < FD->getNumParams())
431 ParamDecl = FD->getParamDecl(i);
432 if (PreVisitProcessArg(C, Call.getArgSVal(i), Call.getArgSourceRange(i),
433 Call.getArgExpr(i), /*IsFirstArgument=*/i == 0,
434 checkUninitFields, Call, *BT, ParamDecl))
438 // If we make it here, record our assumptions about the callee.
439 C.addTransition(State);
442 void CallAndMessageChecker::checkPreObjCMessage(const ObjCMethodCall &msg,
443 CheckerContext &C) const {
444 SVal recVal = msg.getReceiverSVal();
445 if (recVal.isUndef()) {
446 if (ExplodedNode *N = C.generateErrorNode()) {
447 BugType *BT = nullptr;
448 switch (msg.getMessageKind()) {
451 BT_msg_undef.reset(new BuiltinBug(this,
452 "Receiver in message expression "
453 "is an uninitialized value"));
454 BT = BT_msg_undef.get();
456 case OCM_PropertyAccess:
457 if (!BT_objc_prop_undef)
458 BT_objc_prop_undef.reset(new BuiltinBug(
459 this, "Property access on an uninitialized object pointer"));
460 BT = BT_objc_prop_undef.get();
463 if (!BT_objc_subscript_undef)
464 BT_objc_subscript_undef.reset(new BuiltinBug(
465 this, "Subscript access on an uninitialized object pointer"));
466 BT = BT_objc_subscript_undef.get();
469 assert(BT && "Unknown message kind.");
471 auto R = llvm::make_unique<BugReport>(*BT, BT->getName(), N);
472 const ObjCMessageExpr *ME = msg.getOriginExpr();
473 R->addRange(ME->getReceiverRange());
475 // FIXME: getTrackNullOrUndefValueVisitor can't handle "super" yet.
476 if (const Expr *ReceiverE = ME->getInstanceReceiver())
477 bugreporter::trackNullOrUndefValue(N, ReceiverE, *R);
478 C.emitReport(std::move(R));
484 void CallAndMessageChecker::checkObjCMessageNil(const ObjCMethodCall &msg,
485 CheckerContext &C) const {
486 HandleNilReceiver(C, C.getState(), msg);
489 void CallAndMessageChecker::emitNilReceiverBug(CheckerContext &C,
490 const ObjCMethodCall &msg,
491 ExplodedNode *N) const {
495 new BuiltinBug(this, "Receiver in message expression is 'nil'"));
497 const ObjCMessageExpr *ME = msg.getOriginExpr();
499 QualType ResTy = msg.getResultType();
501 SmallString<200> buf;
502 llvm::raw_svector_ostream os(buf);
503 os << "The receiver of message '";
504 ME->getSelector().print(os);
506 if (ResTy->isReferenceType()) {
507 os << ", which results in forming a null reference";
509 os << " and returns a value of type '";
510 msg.getResultType().print(os, C.getLangOpts());
511 os << "' that will be garbage";
514 auto report = llvm::make_unique<BugReport>(*BT_msg_ret, os.str(), N);
515 report->addRange(ME->getReceiverRange());
516 // FIXME: This won't track "self" in messages to super.
517 if (const Expr *receiver = ME->getInstanceReceiver()) {
518 bugreporter::trackNullOrUndefValue(N, receiver, *report);
520 C.emitReport(std::move(report));
523 static bool supportsNilWithFloatRet(const llvm::Triple &triple) {
524 return (triple.getVendor() == llvm::Triple::Apple &&
525 (triple.isiOS() || triple.isWatchOS() ||
526 !triple.isMacOSXVersionLT(10,5)));
529 void CallAndMessageChecker::HandleNilReceiver(CheckerContext &C,
530 ProgramStateRef state,
531 const ObjCMethodCall &Msg) const {
532 ASTContext &Ctx = C.getASTContext();
533 static CheckerProgramPointTag Tag(this, "NilReceiver");
535 // Check the return type of the message expression. A message to nil will
536 // return different values depending on the return type and the architecture.
537 QualType RetTy = Msg.getResultType();
538 CanQualType CanRetTy = Ctx.getCanonicalType(RetTy);
539 const LocationContext *LCtx = C.getLocationContext();
541 if (CanRetTy->isStructureOrClassType()) {
542 // Structure returns are safe since the compiler zeroes them out.
543 SVal V = C.getSValBuilder().makeZeroVal(RetTy);
544 C.addTransition(state->BindExpr(Msg.getOriginExpr(), LCtx, V), &Tag);
548 // Other cases: check if sizeof(return type) > sizeof(void*)
549 if (CanRetTy != Ctx.VoidTy && C.getLocationContext()->getParentMap()
550 .isConsumedExpr(Msg.getOriginExpr())) {
551 // Compute: sizeof(void *) and sizeof(return type)
552 const uint64_t voidPtrSize = Ctx.getTypeSize(Ctx.VoidPtrTy);
553 const uint64_t returnTypeSize = Ctx.getTypeSize(CanRetTy);
555 if (CanRetTy.getTypePtr()->isReferenceType()||
556 (voidPtrSize < returnTypeSize &&
557 !(supportsNilWithFloatRet(Ctx.getTargetInfo().getTriple()) &&
558 (Ctx.FloatTy == CanRetTy ||
559 Ctx.DoubleTy == CanRetTy ||
560 Ctx.LongDoubleTy == CanRetTy ||
561 Ctx.LongLongTy == CanRetTy ||
562 Ctx.UnsignedLongLongTy == CanRetTy)))) {
563 if (ExplodedNode *N = C.generateErrorNode(state, &Tag))
564 emitNilReceiverBug(C, Msg, N);
568 // Handle the safe cases where the return value is 0 if the
571 // FIXME: For now take the conservative approach that we only
572 // return null values if we *know* that the receiver is nil.
573 // This is because we can have surprises like:
575 // ... = [[NSScreens screens] objectAtIndex:0];
577 // What can happen is that [... screens] could return nil, but
578 // it most likely isn't nil. We should assume the semantics
579 // of this case unless we have *a lot* more knowledge.
581 SVal V = C.getSValBuilder().makeZeroVal(RetTy);
582 C.addTransition(state->BindExpr(Msg.getOriginExpr(), LCtx, V), &Tag);
586 C.addTransition(state);
589 #define REGISTER_CHECKER(name) \
590 void ento::register##name(CheckerManager &mgr) { \
591 CallAndMessageChecker *Checker = \
592 mgr.registerChecker<CallAndMessageChecker>(); \
593 Checker->Filter.Check_##name = true; \
594 Checker->Filter.CheckName_##name = mgr.getCurrentCheckName(); \
597 REGISTER_CHECKER(CallAndMessageUnInitRefArg)
598 REGISTER_CHECKER(CallAndMessageChecker)