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 "InternalChecks.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/PathSensitive/CheckerVisitor.h"
21 using namespace clang;
25 class CallAndMessageChecker
26 : public CheckerVisitor<CallAndMessageChecker> {
27 BugType *BT_call_null;
28 BugType *BT_call_undef;
30 BugType *BT_msg_undef;
34 CallAndMessageChecker() :
35 BT_call_null(0), BT_call_undef(0), BT_call_arg(0),
36 BT_msg_undef(0), BT_msg_arg(0), BT_msg_ret(0) {}
38 static void *getTag() {
43 void PreVisitCallExpr(CheckerContext &C, const CallExpr *CE);
44 void preVisitObjCMessage(CheckerContext &C, ObjCMessage msg);
45 bool evalNilReceiver(CheckerContext &C, ObjCMessage msg);
48 void PreVisitProcessArgs(CheckerContext &C, CallOrObjCMessage callOrMsg,
49 const char *BT_desc, BugType *&BT);
50 bool PreVisitProcessArg(CheckerContext &C, SVal V, SourceRange argRange,
51 const Expr *argEx, const char *BT_desc, BugType *&BT);
53 void EmitBadCall(BugType *BT, CheckerContext &C, const CallExpr *CE);
54 void emitNilReceiverBug(CheckerContext &C, const ObjCMessage &msg,
57 void HandleNilReceiver(CheckerContext &C, const GRState *state,
60 void LazyInit_BT(const char *desc, BugType *&BT) {
62 BT = new BuiltinBug(desc);
65 } // end anonymous namespace
67 void ento::RegisterCallAndMessageChecker(ExprEngine &Eng) {
68 Eng.registerCheck(new CallAndMessageChecker());
71 void CallAndMessageChecker::EmitBadCall(BugType *BT, CheckerContext &C,
73 ExplodedNode *N = C.generateSink();
77 EnhancedBugReport *R = new EnhancedBugReport(*BT, BT->getName(), N);
78 R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue,
79 bugreporter::GetCalleeExpr(N));
83 void CallAndMessageChecker::PreVisitProcessArgs(CheckerContext &C,
84 CallOrObjCMessage callOrMsg,
87 for (unsigned i = 0, e = callOrMsg.getNumArgs(); i != e; ++i)
88 if (PreVisitProcessArg(C, callOrMsg.getArgSVal(i),
89 callOrMsg.getArgSourceRange(i), callOrMsg.getArg(i),
94 bool CallAndMessageChecker::PreVisitProcessArg(CheckerContext &C,
95 SVal V, SourceRange argRange,
101 if (ExplodedNode *N = C.generateSink()) {
102 LazyInit_BT(BT_desc, BT);
104 // Generate a report for this bug.
105 EnhancedBugReport *R = new EnhancedBugReport(*BT, BT->getName(), N);
106 R->addRange(argRange);
108 R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, argEx);
114 if (const nonloc::LazyCompoundVal *LV =
115 dyn_cast<nonloc::LazyCompoundVal>(&V)) {
117 class FindUninitializedField {
119 llvm::SmallVector<const FieldDecl *, 10> FieldChain;
122 StoreManager &StoreMgr;
123 MemRegionManager &MrMgr;
126 FindUninitializedField(ASTContext &c, StoreManager &storeMgr,
127 MemRegionManager &mrMgr, Store s)
128 : C(c), StoreMgr(storeMgr), MrMgr(mrMgr), store(s) {}
130 bool Find(const TypedRegion *R) {
131 QualType T = R->getValueType();
132 if (const RecordType *RT = T->getAsStructureType()) {
133 const RecordDecl *RD = RT->getDecl()->getDefinition();
134 assert(RD && "Referred record has no definition");
135 for (RecordDecl::field_iterator I =
136 RD->field_begin(), E = RD->field_end(); I!=E; ++I) {
137 const FieldRegion *FR = MrMgr.getFieldRegion(*I, R);
138 FieldChain.push_back(*I);
140 if (T->getAsStructureType()) {
145 const SVal &V = StoreMgr.Retrieve(store, loc::MemRegionVal(FR));
149 FieldChain.pop_back();
157 const LazyCompoundValData *D = LV->getCVData();
158 FindUninitializedField F(C.getASTContext(),
159 C.getState()->getStateManager().getStoreManager(),
160 C.getSValBuilder().getRegionManager(),
163 if (F.Find(D->getRegion())) {
164 if (ExplodedNode *N = C.generateSink()) {
165 LazyInit_BT(BT_desc, BT);
166 llvm::SmallString<512> Str;
167 llvm::raw_svector_ostream os(Str);
168 os << "Passed-by-value struct argument contains uninitialized data";
170 if (F.FieldChain.size() == 1)
171 os << " (e.g., field: '" << F.FieldChain[0] << "')";
173 os << " (e.g., via the field chain: '";
175 for (llvm::SmallVectorImpl<const FieldDecl *>::iterator
176 DI = F.FieldChain.begin(), DE = F.FieldChain.end(); DI!=DE;++DI){
186 // Generate a report for this bug.
187 EnhancedBugReport *R = new EnhancedBugReport(*BT, os.str(), N);
188 R->addRange(argRange);
190 // FIXME: enhance track back for uninitialized value for arbitrary
201 void CallAndMessageChecker::PreVisitCallExpr(CheckerContext &C,
204 const Expr *Callee = CE->getCallee()->IgnoreParens();
205 SVal L = C.getState()->getSVal(Callee);
210 new BuiltinBug("Called function pointer is an uninitalized pointer value");
211 EmitBadCall(BT_call_undef, C, CE);
215 if (isa<loc::ConcreteInt>(L)) {
218 new BuiltinBug("Called function pointer is null (null dereference)");
219 EmitBadCall(BT_call_null, C, CE);
222 PreVisitProcessArgs(C, CallOrObjCMessage(CE, C.getState()),
223 "Function call argument is an uninitialized value",
227 void CallAndMessageChecker::preVisitObjCMessage(CheckerContext &C,
230 const GRState *state = C.getState();
232 // FIXME: Handle 'super'?
233 if (const Expr *receiver = msg.getInstanceReceiver())
234 if (state->getSVal(receiver).isUndef()) {
235 if (ExplodedNode *N = C.generateSink()) {
238 new BuiltinBug("Receiver in message expression is an uninitialized value");
239 EnhancedBugReport *R =
240 new EnhancedBugReport(*BT_msg_undef, BT_msg_undef->getName(), N);
241 R->addRange(receiver->getSourceRange());
242 R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue,
249 const char *bugDesc = msg.isPropertySetter() ?
250 "Argument for property setter is an uninitialized value"
251 : "Argument in message expression is an uninitialized value";
252 // Check for any arguments that are uninitialized/undefined.
253 PreVisitProcessArgs(C, CallOrObjCMessage(msg, state), bugDesc, BT_msg_arg);
256 bool CallAndMessageChecker::evalNilReceiver(CheckerContext &C,
258 HandleNilReceiver(C, C.getState(), msg);
259 return true; // Nil receiver is not handled elsewhere.
262 void CallAndMessageChecker::emitNilReceiverBug(CheckerContext &C,
263 const ObjCMessage &msg,
268 new BuiltinBug("Receiver in message expression is "
269 "'nil' and returns a garbage value");
271 llvm::SmallString<200> buf;
272 llvm::raw_svector_ostream os(buf);
273 os << "The receiver of message '" << msg.getSelector().getAsString()
274 << "' is nil and returns a value of type '"
275 << msg.getType(C.getASTContext()).getAsString() << "' that will be garbage";
277 EnhancedBugReport *report = new EnhancedBugReport(*BT_msg_ret, os.str(), N);
278 if (const Expr *receiver = msg.getInstanceReceiver()) {
279 report->addRange(receiver->getSourceRange());
280 report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue,
283 C.EmitReport(report);
286 static bool supportsNilWithFloatRet(const llvm::Triple &triple) {
287 return triple.getVendor() == llvm::Triple::Apple &&
288 (triple.getDarwinMajorNumber() >= 9 ||
289 triple.getArch() == llvm::Triple::arm ||
290 triple.getArch() == llvm::Triple::thumb);
293 void CallAndMessageChecker::HandleNilReceiver(CheckerContext &C,
294 const GRState *state,
296 ASTContext &Ctx = C.getASTContext();
298 // Check the return type of the message expression. A message to nil will
299 // return different values depending on the return type and the architecture.
300 QualType RetTy = msg.getType(Ctx);
302 CanQualType CanRetTy = Ctx.getCanonicalType(RetTy);
304 if (CanRetTy->isStructureOrClassType()) {
305 // FIXME: At some point we shouldn't rely on isConsumedExpr(), but instead
306 // have the "use of undefined value" be smarter about where the
307 // undefined value came from.
308 if (C.getPredecessor()->getParentMap().isConsumedExpr(msg.getOriginExpr())){
309 if (ExplodedNode* N = C.generateSink(state))
310 emitNilReceiverBug(C, msg, N);
314 // The result is not consumed by a surrounding expression. Just propagate
315 // the current state.
316 C.addTransition(state);
320 // Other cases: check if the return type is smaller than void*.
321 if (CanRetTy != Ctx.VoidTy &&
322 C.getPredecessor()->getParentMap().isConsumedExpr(msg.getOriginExpr())) {
323 // Compute: sizeof(void *) and sizeof(return type)
324 const uint64_t voidPtrSize = Ctx.getTypeSize(Ctx.VoidPtrTy);
325 const uint64_t returnTypeSize = Ctx.getTypeSize(CanRetTy);
327 if (voidPtrSize < returnTypeSize &&
328 !(supportsNilWithFloatRet(Ctx.Target.getTriple()) &&
329 (Ctx.FloatTy == CanRetTy ||
330 Ctx.DoubleTy == CanRetTy ||
331 Ctx.LongDoubleTy == CanRetTy ||
332 Ctx.LongLongTy == CanRetTy ||
333 Ctx.UnsignedLongLongTy == CanRetTy))) {
334 if (ExplodedNode* N = C.generateSink(state))
335 emitNilReceiverBug(C, msg, N);
339 // Handle the safe cases where the return value is 0 if the
342 // FIXME: For now take the conservative approach that we only
343 // return null values if we *know* that the receiver is nil.
344 // This is because we can have surprises like:
346 // ... = [[NSScreens screens] objectAtIndex:0];
348 // What can happen is that [... screens] could return nil, but
349 // it most likely isn't nil. We should assume the semantics
350 // of this case unless we have *a lot* more knowledge.
352 SVal V = C.getSValBuilder().makeZeroVal(msg.getType(Ctx));
353 C.generateNode(state->BindExpr(msg.getOriginExpr(), V));
357 C.addTransition(state);