1 //===--- CallAndMessageChecker.cpp ------------------------------*- C++ -*--==//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This defines CallAndMessageChecker, a builtin checker that checks for various
10 // errors of call and objc message expressions.
12 //===----------------------------------------------------------------------===//
14 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
15 #include "clang/AST/ParentMap.h"
16 #include "clang/Basic/TargetInfo.h"
17 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
18 #include "clang/StaticAnalyzer/Core/Checker.h"
19 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
21 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/ADT/StringExtras.h"
24 #include "llvm/Support/raw_ostream.h"
26 using namespace clang;
31 class CallAndMessageChecker
32 : public Checker< check::PreStmt<CallExpr>,
33 check::PreStmt<CXXDeleteExpr>,
34 check::PreObjCMessage,
35 check::ObjCMessageNil,
37 mutable std::unique_ptr<BugType> BT_call_null;
38 mutable std::unique_ptr<BugType> BT_call_undef;
39 mutable std::unique_ptr<BugType> BT_cxx_call_null;
40 mutable std::unique_ptr<BugType> BT_cxx_call_undef;
41 mutable std::unique_ptr<BugType> BT_call_arg;
42 mutable std::unique_ptr<BugType> BT_cxx_delete_undef;
43 mutable std::unique_ptr<BugType> BT_msg_undef;
44 mutable std::unique_ptr<BugType> BT_objc_prop_undef;
45 mutable std::unique_ptr<BugType> BT_objc_subscript_undef;
46 mutable std::unique_ptr<BugType> BT_msg_arg;
47 mutable std::unique_ptr<BugType> BT_msg_ret;
48 mutable std::unique_ptr<BugType> BT_call_few_args;
51 DefaultBool Check_CallAndMessageUnInitRefArg;
52 CheckName CheckName_CallAndMessageUnInitRefArg;
54 void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
55 void checkPreStmt(const CXXDeleteExpr *DE, CheckerContext &C) const;
56 void checkPreObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;
58 /// Fill in the return value that results from messaging nil based on the
59 /// return type and architecture and diagnose if the return value will be
61 void checkObjCMessageNil(const ObjCMethodCall &msg, CheckerContext &C) const;
63 void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
66 bool PreVisitProcessArg(CheckerContext &C, SVal V, SourceRange ArgRange,
67 const Expr *ArgEx, int ArgumentNumber,
68 bool CheckUninitFields, const CallEvent &Call,
69 std::unique_ptr<BugType> &BT,
70 const ParmVarDecl *ParamDecl) const;
72 static void emitBadCall(BugType *BT, CheckerContext &C, const Expr *BadE);
73 void emitNilReceiverBug(CheckerContext &C, const ObjCMethodCall &msg,
74 ExplodedNode *N) const;
76 void HandleNilReceiver(CheckerContext &C,
77 ProgramStateRef state,
78 const ObjCMethodCall &msg) const;
80 void LazyInit_BT(const char *desc, std::unique_ptr<BugType> &BT) const {
82 BT.reset(new BuiltinBug(this, desc));
84 bool uninitRefOrPointer(CheckerContext &C, const SVal &V,
85 SourceRange ArgRange, const Expr *ArgEx,
86 std::unique_ptr<BugType> &BT,
87 const ParmVarDecl *ParamDecl, const char *BD,
88 int ArgumentNumber) const;
90 } // end anonymous namespace
92 void CallAndMessageChecker::emitBadCall(BugType *BT, CheckerContext &C,
94 ExplodedNode *N = C.generateErrorNode();
98 auto R = llvm::make_unique<BugReport>(*BT, BT->getName(), N);
100 R->addRange(BadE->getSourceRange());
101 if (BadE->isGLValue())
102 BadE = bugreporter::getDerefExpr(BadE);
103 bugreporter::trackExpressionValue(N, BadE, *R);
105 C.emitReport(std::move(R));
108 static void describeUninitializedArgumentInCall(const CallEvent &Call,
110 llvm::raw_svector_ostream &Os) {
111 switch (Call.getKind()) {
112 case CE_ObjCMessage: {
113 const ObjCMethodCall &Msg = cast<ObjCMethodCall>(Call);
114 switch (Msg.getMessageKind()) {
116 Os << (ArgumentNumber + 1) << llvm::getOrdinalSuffix(ArgumentNumber + 1)
117 << " argument in message expression is an uninitialized value";
119 case OCM_PropertyAccess:
120 assert(Msg.isSetter() && "Getters have no args");
121 Os << "Argument for property setter is an uninitialized value";
124 if (Msg.isSetter() && (ArgumentNumber == 0))
125 Os << "Argument for subscript setter is an uninitialized value";
127 Os << "Subscript index is an uninitialized value";
130 llvm_unreachable("Unknown message kind.");
133 Os << (ArgumentNumber + 1) << llvm::getOrdinalSuffix(ArgumentNumber + 1)
134 << " block call argument is an uninitialized value";
137 Os << (ArgumentNumber + 1) << llvm::getOrdinalSuffix(ArgumentNumber + 1)
138 << " function call argument is an uninitialized value";
143 bool CallAndMessageChecker::uninitRefOrPointer(
144 CheckerContext &C, const SVal &V, SourceRange ArgRange, const Expr *ArgEx,
145 std::unique_ptr<BugType> &BT, const ParmVarDecl *ParamDecl, const char *BD,
146 int ArgumentNumber) const {
147 if (!Check_CallAndMessageUnInitRefArg)
150 // No parameter declaration available, i.e. variadic function argument.
154 // If parameter is declared as pointer to const in function declaration,
155 // then check if corresponding argument in function call is
156 // pointing to undefined symbol value (uninitialized memory).
157 SmallString<200> Buf;
158 llvm::raw_svector_ostream Os(Buf);
160 if (ParamDecl->getType()->isPointerType()) {
161 Os << (ArgumentNumber + 1) << llvm::getOrdinalSuffix(ArgumentNumber + 1)
162 << " function call argument is a pointer to uninitialized value";
163 } else if (ParamDecl->getType()->isReferenceType()) {
164 Os << (ArgumentNumber + 1) << llvm::getOrdinalSuffix(ArgumentNumber + 1)
165 << " function call argument is an uninitialized value";
169 if(!ParamDecl->getType()->getPointeeType().isConstQualified())
172 if (const MemRegion *SValMemRegion = V.getAsRegion()) {
173 const ProgramStateRef State = C.getState();
174 const SVal PSV = State->getSVal(SValMemRegion, C.getASTContext().CharTy);
176 if (ExplodedNode *N = C.generateErrorNode()) {
178 auto R = llvm::make_unique<BugReport>(*BT, Os.str(), N);
179 R->addRange(ArgRange);
181 bugreporter::trackExpressionValue(N, ArgEx, *R);
183 C.emitReport(std::move(R));
192 class FindUninitializedField {
194 SmallVector<const FieldDecl *, 10> FieldChain;
197 StoreManager &StoreMgr;
198 MemRegionManager &MrMgr;
202 FindUninitializedField(StoreManager &storeMgr, MemRegionManager &mrMgr,
204 : StoreMgr(storeMgr), MrMgr(mrMgr), store(s) {}
206 bool Find(const TypedValueRegion *R) {
207 QualType T = R->getValueType();
208 if (const RecordType *RT = T->getAsStructureType()) {
209 const RecordDecl *RD = RT->getDecl()->getDefinition();
210 assert(RD && "Referred record has no definition");
211 for (const auto *I : RD->fields()) {
212 const FieldRegion *FR = MrMgr.getFieldRegion(I, R);
213 FieldChain.push_back(I);
215 if (T->getAsStructureType()) {
219 const SVal &V = StoreMgr.getBinding(store, loc::MemRegionVal(FR));
223 FieldChain.pop_back();
232 bool CallAndMessageChecker::PreVisitProcessArg(CheckerContext &C,
234 SourceRange ArgRange,
237 bool CheckUninitFields,
238 const CallEvent &Call,
239 std::unique_ptr<BugType> &BT,
240 const ParmVarDecl *ParamDecl
242 const char *BD = "Uninitialized argument value";
244 if (uninitRefOrPointer(C, V, ArgRange, ArgEx, BT, ParamDecl, BD,
249 if (ExplodedNode *N = C.generateErrorNode()) {
251 // Generate a report for this bug.
252 SmallString<200> Buf;
253 llvm::raw_svector_ostream Os(Buf);
254 describeUninitializedArgumentInCall(Call, ArgumentNumber, Os);
255 auto R = llvm::make_unique<BugReport>(*BT, Os.str(), N);
257 R->addRange(ArgRange);
259 bugreporter::trackExpressionValue(N, ArgEx, *R);
260 C.emitReport(std::move(R));
265 if (!CheckUninitFields)
268 if (auto LV = V.getAs<nonloc::LazyCompoundVal>()) {
269 const LazyCompoundValData *D = LV->getCVData();
270 FindUninitializedField F(C.getState()->getStateManager().getStoreManager(),
271 C.getSValBuilder().getRegionManager(),
274 if (F.Find(D->getRegion())) {
275 if (ExplodedNode *N = C.generateErrorNode()) {
277 SmallString<512> Str;
278 llvm::raw_svector_ostream os(Str);
279 os << "Passed-by-value struct argument contains uninitialized data";
281 if (F.FieldChain.size() == 1)
282 os << " (e.g., field: '" << *F.FieldChain[0] << "')";
284 os << " (e.g., via the field chain: '";
286 for (SmallVectorImpl<const FieldDecl *>::iterator
287 DI = F.FieldChain.begin(), DE = F.FieldChain.end(); DI!=DE;++DI){
297 // Generate a report for this bug.
298 auto R = llvm::make_unique<BugReport>(*BT, os.str(), N);
299 R->addRange(ArgRange);
302 bugreporter::trackExpressionValue(N, ArgEx, *R);
303 // FIXME: enhance track back for uninitialized value for arbitrary
305 C.emitReport(std::move(R));
314 void CallAndMessageChecker::checkPreStmt(const CallExpr *CE,
315 CheckerContext &C) const{
317 const Expr *Callee = CE->getCallee()->IgnoreParens();
318 ProgramStateRef State = C.getState();
319 const LocationContext *LCtx = C.getLocationContext();
320 SVal L = State->getSVal(Callee, LCtx);
324 BT_call_undef.reset(new BuiltinBug(
325 this, "Called function pointer is an uninitialized pointer value"));
326 emitBadCall(BT_call_undef.get(), C, Callee);
330 ProgramStateRef StNonNull, StNull;
331 std::tie(StNonNull, StNull) = State->assume(L.castAs<DefinedOrUnknownSVal>());
333 if (StNull && !StNonNull) {
335 BT_call_null.reset(new BuiltinBug(
336 this, "Called function pointer is null (null dereference)"));
337 emitBadCall(BT_call_null.get(), C, Callee);
341 C.addTransition(StNonNull);
344 void CallAndMessageChecker::checkPreStmt(const CXXDeleteExpr *DE,
345 CheckerContext &C) const {
347 SVal Arg = C.getSVal(DE->getArgument());
350 ExplodedNode *N = C.generateErrorNode();
353 if (!BT_cxx_delete_undef)
354 BT_cxx_delete_undef.reset(
355 new BuiltinBug(this, "Uninitialized argument value"));
356 if (DE->isArrayFormAsWritten())
357 Desc = "Argument to 'delete[]' is uninitialized";
359 Desc = "Argument to 'delete' is uninitialized";
360 BugType *BT = BT_cxx_delete_undef.get();
361 auto R = llvm::make_unique<BugReport>(*BT, Desc, N);
362 bugreporter::trackExpressionValue(N, DE, *R);
363 C.emitReport(std::move(R));
368 void CallAndMessageChecker::checkPreCall(const CallEvent &Call,
369 CheckerContext &C) const {
370 ProgramStateRef State = C.getState();
372 // If this is a call to a C++ method, check if the callee is null or
374 if (const CXXInstanceCall *CC = dyn_cast<CXXInstanceCall>(&Call)) {
375 SVal V = CC->getCXXThisVal();
377 if (!BT_cxx_call_undef)
378 BT_cxx_call_undef.reset(
379 new BuiltinBug(this, "Called C++ object pointer is uninitialized"));
380 emitBadCall(BT_cxx_call_undef.get(), C, CC->getCXXThisExpr());
384 ProgramStateRef StNonNull, StNull;
385 std::tie(StNonNull, StNull) =
386 State->assume(V.castAs<DefinedOrUnknownSVal>());
388 if (StNull && !StNonNull) {
389 if (!BT_cxx_call_null)
390 BT_cxx_call_null.reset(
391 new BuiltinBug(this, "Called C++ object pointer is null"));
392 emitBadCall(BT_cxx_call_null.get(), C, CC->getCXXThisExpr());
399 const Decl *D = Call.getDecl();
400 if (D && (isa<FunctionDecl>(D) || isa<BlockDecl>(D))) {
401 // If we have a function or block declaration, we can make sure we pass
402 // enough parameters.
403 unsigned Params = Call.parameters().size();
404 if (Call.getNumArgs() < Params) {
405 ExplodedNode *N = C.generateErrorNode();
409 LazyInit_BT("Function call with too few arguments", BT_call_few_args);
411 SmallString<512> Str;
412 llvm::raw_svector_ostream os(Str);
413 if (isa<FunctionDecl>(D)) {
416 assert(isa<BlockDecl>(D));
419 os << "taking " << Params << " argument"
420 << (Params == 1 ? "" : "s") << " is called with fewer ("
421 << Call.getNumArgs() << ")";
424 llvm::make_unique<BugReport>(*BT_call_few_args, os.str(), N));
428 // Don't check for uninitialized field values in arguments if the
429 // caller has a body that is available and we have the chance to inline it.
430 // This is a hack, but is a reasonable compromise betweens sometimes warning
431 // and sometimes not depending on if we decide to inline a function.
432 const bool checkUninitFields =
433 !(C.getAnalysisManager().shouldInlineCall() && (D && D->getBody()));
435 std::unique_ptr<BugType> *BT;
436 if (isa<ObjCMethodCall>(Call))
441 const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D);
442 for (unsigned i = 0, e = Call.getNumArgs(); i != e; ++i) {
443 const ParmVarDecl *ParamDecl = nullptr;
444 if(FD && i < FD->getNumParams())
445 ParamDecl = FD->getParamDecl(i);
446 if (PreVisitProcessArg(C, Call.getArgSVal(i), Call.getArgSourceRange(i),
447 Call.getArgExpr(i), i,
448 checkUninitFields, Call, *BT, ParamDecl))
452 // If we make it here, record our assumptions about the callee.
453 C.addTransition(State);
456 void CallAndMessageChecker::checkPreObjCMessage(const ObjCMethodCall &msg,
457 CheckerContext &C) const {
458 SVal recVal = msg.getReceiverSVal();
459 if (recVal.isUndef()) {
460 if (ExplodedNode *N = C.generateErrorNode()) {
461 BugType *BT = nullptr;
462 switch (msg.getMessageKind()) {
465 BT_msg_undef.reset(new BuiltinBug(this,
466 "Receiver in message expression "
467 "is an uninitialized value"));
468 BT = BT_msg_undef.get();
470 case OCM_PropertyAccess:
471 if (!BT_objc_prop_undef)
472 BT_objc_prop_undef.reset(new BuiltinBug(
473 this, "Property access on an uninitialized object pointer"));
474 BT = BT_objc_prop_undef.get();
477 if (!BT_objc_subscript_undef)
478 BT_objc_subscript_undef.reset(new BuiltinBug(
479 this, "Subscript access on an uninitialized object pointer"));
480 BT = BT_objc_subscript_undef.get();
483 assert(BT && "Unknown message kind.");
485 auto R = llvm::make_unique<BugReport>(*BT, BT->getName(), N);
486 const ObjCMessageExpr *ME = msg.getOriginExpr();
487 R->addRange(ME->getReceiverRange());
489 // FIXME: getTrackNullOrUndefValueVisitor can't handle "super" yet.
490 if (const Expr *ReceiverE = ME->getInstanceReceiver())
491 bugreporter::trackExpressionValue(N, ReceiverE, *R);
492 C.emitReport(std::move(R));
498 void CallAndMessageChecker::checkObjCMessageNil(const ObjCMethodCall &msg,
499 CheckerContext &C) const {
500 HandleNilReceiver(C, C.getState(), msg);
503 void CallAndMessageChecker::emitNilReceiverBug(CheckerContext &C,
504 const ObjCMethodCall &msg,
505 ExplodedNode *N) const {
509 new BuiltinBug(this, "Receiver in message expression is 'nil'"));
511 const ObjCMessageExpr *ME = msg.getOriginExpr();
513 QualType ResTy = msg.getResultType();
515 SmallString<200> buf;
516 llvm::raw_svector_ostream os(buf);
517 os << "The receiver of message '";
518 ME->getSelector().print(os);
520 if (ResTy->isReferenceType()) {
521 os << ", which results in forming a null reference";
523 os << " and returns a value of type '";
524 msg.getResultType().print(os, C.getLangOpts());
525 os << "' that will be garbage";
528 auto report = llvm::make_unique<BugReport>(*BT_msg_ret, os.str(), N);
529 report->addRange(ME->getReceiverRange());
530 // FIXME: This won't track "self" in messages to super.
531 if (const Expr *receiver = ME->getInstanceReceiver()) {
532 bugreporter::trackExpressionValue(N, receiver, *report);
534 C.emitReport(std::move(report));
537 static bool supportsNilWithFloatRet(const llvm::Triple &triple) {
538 return (triple.getVendor() == llvm::Triple::Apple &&
539 (triple.isiOS() || triple.isWatchOS() ||
540 !triple.isMacOSXVersionLT(10,5)));
543 void CallAndMessageChecker::HandleNilReceiver(CheckerContext &C,
544 ProgramStateRef state,
545 const ObjCMethodCall &Msg) const {
546 ASTContext &Ctx = C.getASTContext();
547 static CheckerProgramPointTag Tag(this, "NilReceiver");
549 // Check the return type of the message expression. A message to nil will
550 // return different values depending on the return type and the architecture.
551 QualType RetTy = Msg.getResultType();
552 CanQualType CanRetTy = Ctx.getCanonicalType(RetTy);
553 const LocationContext *LCtx = C.getLocationContext();
555 if (CanRetTy->isStructureOrClassType()) {
556 // Structure returns are safe since the compiler zeroes them out.
557 SVal V = C.getSValBuilder().makeZeroVal(RetTy);
558 C.addTransition(state->BindExpr(Msg.getOriginExpr(), LCtx, V), &Tag);
562 // Other cases: check if sizeof(return type) > sizeof(void*)
563 if (CanRetTy != Ctx.VoidTy && C.getLocationContext()->getParentMap()
564 .isConsumedExpr(Msg.getOriginExpr())) {
565 // Compute: sizeof(void *) and sizeof(return type)
566 const uint64_t voidPtrSize = Ctx.getTypeSize(Ctx.VoidPtrTy);
567 const uint64_t returnTypeSize = Ctx.getTypeSize(CanRetTy);
569 if (CanRetTy.getTypePtr()->isReferenceType()||
570 (voidPtrSize < returnTypeSize &&
571 !(supportsNilWithFloatRet(Ctx.getTargetInfo().getTriple()) &&
572 (Ctx.FloatTy == CanRetTy ||
573 Ctx.DoubleTy == CanRetTy ||
574 Ctx.LongDoubleTy == CanRetTy ||
575 Ctx.LongLongTy == CanRetTy ||
576 Ctx.UnsignedLongLongTy == CanRetTy)))) {
577 if (ExplodedNode *N = C.generateErrorNode(state, &Tag))
578 emitNilReceiverBug(C, Msg, N);
582 // Handle the safe cases where the return value is 0 if the
585 // FIXME: For now take the conservative approach that we only
586 // return null values if we *know* that the receiver is nil.
587 // This is because we can have surprises like:
589 // ... = [[NSScreens screens] objectAtIndex:0];
591 // What can happen is that [... screens] could return nil, but
592 // it most likely isn't nil. We should assume the semantics
593 // of this case unless we have *a lot* more knowledge.
595 SVal V = C.getSValBuilder().makeZeroVal(RetTy);
596 C.addTransition(state->BindExpr(Msg.getOriginExpr(), LCtx, V), &Tag);
600 C.addTransition(state);
603 void ento::registerCallAndMessageChecker(CheckerManager &mgr) {
604 mgr.registerChecker<CallAndMessageChecker>();
607 bool ento::shouldRegisterCallAndMessageChecker(const LangOptions &LO) {
611 void ento::registerCallAndMessageUnInitRefArg(CheckerManager &mgr) {
612 CallAndMessageChecker *Checker = mgr.getChecker<CallAndMessageChecker>();
613 Checker->Check_CallAndMessageUnInitRefArg = true;
614 Checker->CheckName_CallAndMessageUnInitRefArg = mgr.getCurrentCheckName();
617 bool ento::shouldRegisterCallAndMessageUnInitRefArg(const LangOptions &LO) {