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/StaticAnalyzer/Core/Checker.h"
17 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
19 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
20 #include "clang/AST/ParentMap.h"
21 #include "clang/Basic/TargetInfo.h"
23 using namespace clang;
27 class CallAndMessageChecker
28 : public Checker< check::PreStmt<CallExpr>, check::PreObjCMessage > {
29 mutable llvm::OwningPtr<BugType> BT_call_null;
30 mutable llvm::OwningPtr<BugType> BT_call_undef;
31 mutable llvm::OwningPtr<BugType> BT_call_arg;
32 mutable llvm::OwningPtr<BugType> BT_msg_undef;
33 mutable llvm::OwningPtr<BugType> BT_msg_arg;
34 mutable llvm::OwningPtr<BugType> BT_msg_ret;
37 void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
38 void checkPreObjCMessage(ObjCMessage msg, CheckerContext &C) const;
41 static void PreVisitProcessArgs(CheckerContext &C,CallOrObjCMessage callOrMsg,
42 const char *BT_desc, llvm::OwningPtr<BugType> &BT);
43 static bool PreVisitProcessArg(CheckerContext &C, SVal V,SourceRange argRange,
44 const Expr *argEx, const char *BT_desc, llvm::OwningPtr<BugType> &BT);
46 static void EmitBadCall(BugType *BT, CheckerContext &C, const CallExpr *CE);
47 void emitNilReceiverBug(CheckerContext &C, const ObjCMessage &msg,
48 ExplodedNode *N) const;
50 void HandleNilReceiver(CheckerContext &C, const GRState *state,
51 ObjCMessage msg) const;
53 static void LazyInit_BT(const char *desc, llvm::OwningPtr<BugType> &BT) {
55 BT.reset(new BuiltinBug(desc));
58 } // end anonymous namespace
60 void CallAndMessageChecker::EmitBadCall(BugType *BT, CheckerContext &C,
62 ExplodedNode *N = C.generateSink();
66 EnhancedBugReport *R = new EnhancedBugReport(*BT, BT->getName(), N);
67 R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue,
68 bugreporter::GetCalleeExpr(N));
72 void CallAndMessageChecker::PreVisitProcessArgs(CheckerContext &C,
73 CallOrObjCMessage callOrMsg,
75 llvm::OwningPtr<BugType> &BT) {
76 for (unsigned i = 0, e = callOrMsg.getNumArgs(); i != e; ++i)
77 if (PreVisitProcessArg(C, callOrMsg.getArgSVal(i),
78 callOrMsg.getArgSourceRange(i), callOrMsg.getArg(i),
83 bool CallAndMessageChecker::PreVisitProcessArg(CheckerContext &C,
84 SVal V, SourceRange argRange,
87 llvm::OwningPtr<BugType> &BT) {
90 if (ExplodedNode *N = C.generateSink()) {
91 LazyInit_BT(BT_desc, BT);
93 // Generate a report for this bug.
94 EnhancedBugReport *R = new EnhancedBugReport(*BT, BT->getName(), N);
95 R->addRange(argRange);
97 R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, argEx);
103 if (const nonloc::LazyCompoundVal *LV =
104 dyn_cast<nonloc::LazyCompoundVal>(&V)) {
106 class FindUninitializedField {
108 llvm::SmallVector<const FieldDecl *, 10> FieldChain;
111 StoreManager &StoreMgr;
112 MemRegionManager &MrMgr;
115 FindUninitializedField(ASTContext &c, StoreManager &storeMgr,
116 MemRegionManager &mrMgr, Store s)
117 : C(c), StoreMgr(storeMgr), MrMgr(mrMgr), store(s) {}
119 bool Find(const TypedRegion *R) {
120 QualType T = R->getValueType();
121 if (const RecordType *RT = T->getAsStructureType()) {
122 const RecordDecl *RD = RT->getDecl()->getDefinition();
123 assert(RD && "Referred record has no definition");
124 for (RecordDecl::field_iterator I =
125 RD->field_begin(), E = RD->field_end(); I!=E; ++I) {
126 const FieldRegion *FR = MrMgr.getFieldRegion(*I, R);
127 FieldChain.push_back(*I);
129 if (T->getAsStructureType()) {
134 const SVal &V = StoreMgr.Retrieve(store, loc::MemRegionVal(FR));
138 FieldChain.pop_back();
146 const LazyCompoundValData *D = LV->getCVData();
147 FindUninitializedField F(C.getASTContext(),
148 C.getState()->getStateManager().getStoreManager(),
149 C.getSValBuilder().getRegionManager(),
152 if (F.Find(D->getRegion())) {
153 if (ExplodedNode *N = C.generateSink()) {
154 LazyInit_BT(BT_desc, BT);
155 llvm::SmallString<512> Str;
156 llvm::raw_svector_ostream os(Str);
157 os << "Passed-by-value struct argument contains uninitialized data";
159 if (F.FieldChain.size() == 1)
160 os << " (e.g., field: '" << F.FieldChain[0] << "')";
162 os << " (e.g., via the field chain: '";
164 for (llvm::SmallVectorImpl<const FieldDecl *>::iterator
165 DI = F.FieldChain.begin(), DE = F.FieldChain.end(); DI!=DE;++DI){
175 // Generate a report for this bug.
176 EnhancedBugReport *R = new EnhancedBugReport(*BT, os.str(), N);
177 R->addRange(argRange);
179 // FIXME: enhance track back for uninitialized value for arbitrary
190 void CallAndMessageChecker::checkPreStmt(const CallExpr *CE,
191 CheckerContext &C) const{
193 const Expr *Callee = CE->getCallee()->IgnoreParens();
194 SVal L = C.getState()->getSVal(Callee);
198 BT_call_undef.reset(new BuiltinBug("Called function pointer is an "
199 "uninitalized pointer value"));
200 EmitBadCall(BT_call_undef.get(), C, CE);
204 if (isa<loc::ConcreteInt>(L)) {
207 new BuiltinBug("Called function pointer is null (null dereference)"));
208 EmitBadCall(BT_call_null.get(), C, CE);
211 PreVisitProcessArgs(C, CallOrObjCMessage(CE, C.getState()),
212 "Function call argument is an uninitialized value",
216 void CallAndMessageChecker::checkPreObjCMessage(ObjCMessage msg,
217 CheckerContext &C) const {
219 const GRState *state = C.getState();
221 // FIXME: Handle 'super'?
222 if (const Expr *receiver = msg.getInstanceReceiver()) {
223 SVal recVal = state->getSVal(receiver);
224 if (recVal.isUndef()) {
225 if (ExplodedNode *N = C.generateSink()) {
227 BT_msg_undef.reset(new BuiltinBug("Receiver in message expression is "
228 "an uninitialized value"));
229 EnhancedBugReport *R =
230 new EnhancedBugReport(*BT_msg_undef, BT_msg_undef->getName(), N);
231 R->addRange(receiver->getSourceRange());
232 R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue,
238 // Bifurcate the state into nil and non-nil ones.
239 DefinedOrUnknownSVal receiverVal = cast<DefinedOrUnknownSVal>(recVal);
241 const GRState *notNilState, *nilState;
242 llvm::tie(notNilState, nilState) = state->assume(receiverVal);
244 // Handle receiver must be nil.
245 if (nilState && !notNilState) {
246 HandleNilReceiver(C, state, msg);
252 const char *bugDesc = msg.isPropertySetter() ?
253 "Argument for property setter is an uninitialized value"
254 : "Argument in message expression is an uninitialized value";
255 // Check for any arguments that are uninitialized/undefined.
256 PreVisitProcessArgs(C, CallOrObjCMessage(msg, state), bugDesc, BT_msg_arg);
259 void CallAndMessageChecker::emitNilReceiverBug(CheckerContext &C,
260 const ObjCMessage &msg,
261 ExplodedNode *N) const {
265 new BuiltinBug("Receiver in message expression is "
266 "'nil' and returns a garbage value"));
268 llvm::SmallString<200> buf;
269 llvm::raw_svector_ostream os(buf);
270 os << "The receiver of message '" << msg.getSelector().getAsString()
271 << "' is nil and returns a value of type '"
272 << msg.getType(C.getASTContext()).getAsString() << "' that will be garbage";
274 EnhancedBugReport *report = new EnhancedBugReport(*BT_msg_ret, os.str(), N);
275 if (const Expr *receiver = msg.getInstanceReceiver()) {
276 report->addRange(receiver->getSourceRange());
277 report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue,
280 C.EmitReport(report);
283 static bool supportsNilWithFloatRet(const llvm::Triple &triple) {
284 return triple.getVendor() == llvm::Triple::Apple &&
285 (!triple.isMacOSXVersionLT(10,5) ||
286 triple.getArch() == llvm::Triple::arm ||
287 triple.getArch() == llvm::Triple::thumb);
290 void CallAndMessageChecker::HandleNilReceiver(CheckerContext &C,
291 const GRState *state,
292 ObjCMessage msg) const {
293 ASTContext &Ctx = C.getASTContext();
295 // Check the return type of the message expression. A message to nil will
296 // return different values depending on the return type and the architecture.
297 QualType RetTy = msg.getType(Ctx);
299 CanQualType CanRetTy = Ctx.getCanonicalType(RetTy);
301 if (CanRetTy->isStructureOrClassType()) {
302 // FIXME: At some point we shouldn't rely on isConsumedExpr(), but instead
303 // have the "use of undefined value" be smarter about where the
304 // undefined value came from.
305 if (C.getPredecessor()->getParentMap().isConsumedExpr(msg.getOriginExpr())){
306 if (ExplodedNode* N = C.generateSink(state))
307 emitNilReceiverBug(C, msg, N);
311 // The result is not consumed by a surrounding expression. Just propagate
312 // the current state.
313 C.addTransition(state);
317 // Other cases: check if the return type is smaller than void*.
318 if (CanRetTy != Ctx.VoidTy &&
319 C.getPredecessor()->getParentMap().isConsumedExpr(msg.getOriginExpr())) {
320 // Compute: sizeof(void *) and sizeof(return type)
321 const uint64_t voidPtrSize = Ctx.getTypeSize(Ctx.VoidPtrTy);
322 const uint64_t returnTypeSize = Ctx.getTypeSize(CanRetTy);
324 if (voidPtrSize < returnTypeSize &&
325 !(supportsNilWithFloatRet(Ctx.Target.getTriple()) &&
326 (Ctx.FloatTy == CanRetTy ||
327 Ctx.DoubleTy == CanRetTy ||
328 Ctx.LongDoubleTy == CanRetTy ||
329 Ctx.LongLongTy == CanRetTy ||
330 Ctx.UnsignedLongLongTy == CanRetTy))) {
331 if (ExplodedNode* N = C.generateSink(state))
332 emitNilReceiverBug(C, msg, N);
336 // Handle the safe cases where the return value is 0 if the
339 // FIXME: For now take the conservative approach that we only
340 // return null values if we *know* that the receiver is nil.
341 // This is because we can have surprises like:
343 // ... = [[NSScreens screens] objectAtIndex:0];
345 // What can happen is that [... screens] could return nil, but
346 // it most likely isn't nil. We should assume the semantics
347 // of this case unless we have *a lot* more knowledge.
349 SVal V = C.getSValBuilder().makeZeroVal(msg.getType(Ctx));
350 C.generateNode(state->BindExpr(msg.getOriginExpr(), V));
354 C.addTransition(state);
357 void ento::registerCallAndMessageChecker(CheckerManager &mgr) {
358 mgr.registerChecker<CallAndMessageChecker>();