1218887Sdim//===--- CallAndMessageChecker.cpp ------------------------------*- C++ -*--==// 2218887Sdim// 3218887Sdim// The LLVM Compiler Infrastructure 4218887Sdim// 5218887Sdim// This file is distributed under the University of Illinois Open Source 6218887Sdim// License. See LICENSE.TXT for details. 7218887Sdim// 8218887Sdim//===----------------------------------------------------------------------===// 9218887Sdim// 10218887Sdim// This defines CallAndMessageChecker, a builtin checker that checks for various 11218887Sdim// errors of call and objc message expressions. 12218887Sdim// 13218887Sdim//===----------------------------------------------------------------------===// 14218887Sdim 15221345Sdim#include "ClangSACheckers.h" 16249423Sdim#include "clang/AST/ParentMap.h" 17249423Sdim#include "clang/Basic/TargetInfo.h" 18249423Sdim#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" 19221345Sdim#include "clang/StaticAnalyzer/Core/Checker.h" 20221345Sdim#include "clang/StaticAnalyzer/Core/CheckerManager.h" 21239462Sdim#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h" 22221345Sdim#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 23234353Sdim#include "llvm/ADT/SmallString.h" 24249423Sdim#include "llvm/Support/raw_ostream.h" 25218887Sdim 26218887Sdimusing namespace clang; 27218887Sdimusing namespace ento; 28218887Sdim 29218887Sdimnamespace { 30218887Sdimclass CallAndMessageChecker 31239462Sdim : public Checker< check::PreStmt<CallExpr>, check::PreObjCMessage, 32239462Sdim check::PreCall > { 33234353Sdim mutable OwningPtr<BugType> BT_call_null; 34234353Sdim mutable OwningPtr<BugType> BT_call_undef; 35239462Sdim mutable OwningPtr<BugType> BT_cxx_call_null; 36239462Sdim mutable OwningPtr<BugType> BT_cxx_call_undef; 37234353Sdim mutable OwningPtr<BugType> BT_call_arg; 38234353Sdim mutable OwningPtr<BugType> BT_msg_undef; 39234353Sdim mutable OwningPtr<BugType> BT_objc_prop_undef; 40239462Sdim mutable OwningPtr<BugType> BT_objc_subscript_undef; 41234353Sdim mutable OwningPtr<BugType> BT_msg_arg; 42234353Sdim mutable OwningPtr<BugType> BT_msg_ret; 43218887Sdimpublic: 44218887Sdim 45221345Sdim void checkPreStmt(const CallExpr *CE, CheckerContext &C) const; 46239462Sdim void checkPreObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const; 47239462Sdim void checkPreCall(const CallEvent &Call, CheckerContext &C) const; 48218887Sdim 49218887Sdimprivate: 50239462Sdim static bool PreVisitProcessArg(CheckerContext &C, SVal V, 51239462Sdim SourceRange argRange, const Expr *argEx, 52239462Sdim bool IsFirstArgument, bool checkUninitFields, 53239462Sdim const CallEvent &Call, OwningPtr<BugType> &BT); 54218887Sdim 55239462Sdim static void emitBadCall(BugType *BT, CheckerContext &C, const Expr *BadE); 56239462Sdim void emitNilReceiverBug(CheckerContext &C, const ObjCMethodCall &msg, 57221345Sdim ExplodedNode *N) const; 58218887Sdim 59226633Sdim void HandleNilReceiver(CheckerContext &C, 60234353Sdim ProgramStateRef state, 61239462Sdim const ObjCMethodCall &msg) const; 62218887Sdim 63234353Sdim static void LazyInit_BT(const char *desc, OwningPtr<BugType> &BT) { 64218887Sdim if (!BT) 65221345Sdim BT.reset(new BuiltinBug(desc)); 66218887Sdim } 67218887Sdim}; 68218887Sdim} // end anonymous namespace 69218887Sdim 70239462Sdimvoid CallAndMessageChecker::emitBadCall(BugType *BT, CheckerContext &C, 71239462Sdim const Expr *BadE) { 72218887Sdim ExplodedNode *N = C.generateSink(); 73218887Sdim if (!N) 74218887Sdim return; 75218887Sdim 76226633Sdim BugReport *R = new BugReport(*BT, BT->getName(), N); 77239462Sdim if (BadE) { 78239462Sdim R->addRange(BadE->getSourceRange()); 79249423Sdim if (BadE->isGLValue()) 80249423Sdim BadE = bugreporter::getDerefExpr(BadE); 81243830Sdim bugreporter::trackNullOrUndefValue(N, BadE, *R); 82239462Sdim } 83243830Sdim C.emitReport(R); 84218887Sdim} 85218887Sdim 86243830Sdimstatic StringRef describeUninitializedArgumentInCall(const CallEvent &Call, 87243830Sdim bool IsFirstArgument) { 88239462Sdim switch (Call.getKind()) { 89239462Sdim case CE_ObjCMessage: { 90239462Sdim const ObjCMethodCall &Msg = cast<ObjCMethodCall>(Call); 91239462Sdim switch (Msg.getMessageKind()) { 92239462Sdim case OCM_Message: 93239462Sdim return "Argument in message expression is an uninitialized value"; 94239462Sdim case OCM_PropertyAccess: 95239462Sdim assert(Msg.isSetter() && "Getters have no args"); 96239462Sdim return "Argument for property setter is an uninitialized value"; 97239462Sdim case OCM_Subscript: 98239462Sdim if (Msg.isSetter() && IsFirstArgument) 99239462Sdim return "Argument for subscript setter is an uninitialized value"; 100239462Sdim return "Subscript index is an uninitialized value"; 101239462Sdim } 102239462Sdim llvm_unreachable("Unknown message kind."); 103239462Sdim } 104239462Sdim case CE_Block: 105239462Sdim return "Block call argument is an uninitialized value"; 106239462Sdim default: 107239462Sdim return "Function call argument is an uninitialized value"; 108239462Sdim } 109218887Sdim} 110218887Sdim 111218887Sdimbool CallAndMessageChecker::PreVisitProcessArg(CheckerContext &C, 112218887Sdim SVal V, SourceRange argRange, 113218887Sdim const Expr *argEx, 114239462Sdim bool IsFirstArgument, 115239462Sdim bool checkUninitFields, 116239462Sdim const CallEvent &Call, 117234353Sdim OwningPtr<BugType> &BT) { 118218887Sdim if (V.isUndef()) { 119218887Sdim if (ExplodedNode *N = C.generateSink()) { 120239462Sdim LazyInit_BT("Uninitialized argument value", BT); 121218887Sdim 122218887Sdim // Generate a report for this bug. 123239462Sdim StringRef Desc = describeUninitializedArgumentInCall(Call, 124239462Sdim IsFirstArgument); 125239462Sdim BugReport *R = new BugReport(*BT, Desc, N); 126218887Sdim R->addRange(argRange); 127218887Sdim if (argEx) 128243830Sdim bugreporter::trackNullOrUndefValue(N, argEx, *R); 129243830Sdim C.emitReport(R); 130218887Sdim } 131218887Sdim return true; 132218887Sdim } 133218887Sdim 134234353Sdim if (!checkUninitFields) 135234353Sdim return false; 136218887Sdim 137249423Sdim if (Optional<nonloc::LazyCompoundVal> LV = 138249423Sdim V.getAs<nonloc::LazyCompoundVal>()) { 139249423Sdim 140218887Sdim class FindUninitializedField { 141218887Sdim public: 142226633Sdim SmallVector<const FieldDecl *, 10> FieldChain; 143218887Sdim private: 144218887Sdim StoreManager &StoreMgr; 145218887Sdim MemRegionManager &MrMgr; 146218887Sdim Store store; 147218887Sdim public: 148239462Sdim FindUninitializedField(StoreManager &storeMgr, 149218887Sdim MemRegionManager &mrMgr, Store s) 150239462Sdim : StoreMgr(storeMgr), MrMgr(mrMgr), store(s) {} 151218887Sdim 152226633Sdim bool Find(const TypedValueRegion *R) { 153218887Sdim QualType T = R->getValueType(); 154218887Sdim if (const RecordType *RT = T->getAsStructureType()) { 155218887Sdim const RecordDecl *RD = RT->getDecl()->getDefinition(); 156218887Sdim assert(RD && "Referred record has no definition"); 157218887Sdim for (RecordDecl::field_iterator I = 158218887Sdim RD->field_begin(), E = RD->field_end(); I!=E; ++I) { 159218887Sdim const FieldRegion *FR = MrMgr.getFieldRegion(*I, R); 160218887Sdim FieldChain.push_back(*I); 161239462Sdim T = I->getType(); 162218887Sdim if (T->getAsStructureType()) { 163218887Sdim if (Find(FR)) 164218887Sdim return true; 165218887Sdim } 166218887Sdim else { 167234353Sdim const SVal &V = StoreMgr.getBinding(store, loc::MemRegionVal(FR)); 168218887Sdim if (V.isUndef()) 169218887Sdim return true; 170218887Sdim } 171218887Sdim FieldChain.pop_back(); 172218887Sdim } 173218887Sdim } 174218887Sdim 175218887Sdim return false; 176218887Sdim } 177218887Sdim }; 178218887Sdim 179218887Sdim const LazyCompoundValData *D = LV->getCVData(); 180239462Sdim FindUninitializedField F(C.getState()->getStateManager().getStoreManager(), 181218887Sdim C.getSValBuilder().getRegionManager(), 182218887Sdim D->getStore()); 183218887Sdim 184218887Sdim if (F.Find(D->getRegion())) { 185218887Sdim if (ExplodedNode *N = C.generateSink()) { 186239462Sdim LazyInit_BT("Uninitialized argument value", BT); 187234353Sdim SmallString<512> Str; 188218887Sdim llvm::raw_svector_ostream os(Str); 189218887Sdim os << "Passed-by-value struct argument contains uninitialized data"; 190218887Sdim 191218887Sdim if (F.FieldChain.size() == 1) 192226633Sdim os << " (e.g., field: '" << *F.FieldChain[0] << "')"; 193218887Sdim else { 194218887Sdim os << " (e.g., via the field chain: '"; 195218887Sdim bool first = true; 196226633Sdim for (SmallVectorImpl<const FieldDecl *>::iterator 197218887Sdim DI = F.FieldChain.begin(), DE = F.FieldChain.end(); DI!=DE;++DI){ 198218887Sdim if (first) 199218887Sdim first = false; 200218887Sdim else 201218887Sdim os << '.'; 202226633Sdim os << **DI; 203218887Sdim } 204218887Sdim os << "')"; 205218887Sdim } 206218887Sdim 207218887Sdim // Generate a report for this bug. 208226633Sdim BugReport *R = new BugReport(*BT, os.str(), N); 209218887Sdim R->addRange(argRange); 210218887Sdim 211218887Sdim // FIXME: enhance track back for uninitialized value for arbitrary 212218887Sdim // memregions 213243830Sdim C.emitReport(R); 214218887Sdim } 215218887Sdim return true; 216218887Sdim } 217218887Sdim } 218218887Sdim 219218887Sdim return false; 220218887Sdim} 221218887Sdim 222221345Sdimvoid CallAndMessageChecker::checkPreStmt(const CallExpr *CE, 223221345Sdim CheckerContext &C) const{ 224218887Sdim 225218887Sdim const Expr *Callee = CE->getCallee()->IgnoreParens(); 226239462Sdim ProgramStateRef State = C.getState(); 227234353Sdim const LocationContext *LCtx = C.getLocationContext(); 228239462Sdim SVal L = State->getSVal(Callee, LCtx); 229218887Sdim 230218887Sdim if (L.isUndef()) { 231218887Sdim if (!BT_call_undef) 232221345Sdim BT_call_undef.reset(new BuiltinBug("Called function pointer is an " 233221345Sdim "uninitalized pointer value")); 234239462Sdim emitBadCall(BT_call_undef.get(), C, Callee); 235218887Sdim return; 236218887Sdim } 237218887Sdim 238239462Sdim ProgramStateRef StNonNull, StNull; 239249423Sdim llvm::tie(StNonNull, StNull) = 240249423Sdim State->assume(L.castAs<DefinedOrUnknownSVal>()); 241239462Sdim 242239462Sdim if (StNull && !StNonNull) { 243218887Sdim if (!BT_call_null) 244221345Sdim BT_call_null.reset( 245221345Sdim new BuiltinBug("Called function pointer is null (null dereference)")); 246239462Sdim emitBadCall(BT_call_null.get(), C, Callee); 247218887Sdim } 248218887Sdim 249239462Sdim C.addTransition(StNonNull); 250218887Sdim} 251218887Sdim 252239462Sdimvoid CallAndMessageChecker::checkPreCall(const CallEvent &Call, 253239462Sdim CheckerContext &C) const { 254239462Sdim ProgramStateRef State = C.getState(); 255218887Sdim 256239462Sdim // If this is a call to a C++ method, check if the callee is null or 257239462Sdim // undefined. 258239462Sdim if (const CXXInstanceCall *CC = dyn_cast<CXXInstanceCall>(&Call)) { 259239462Sdim SVal V = CC->getCXXThisVal(); 260239462Sdim if (V.isUndef()) { 261239462Sdim if (!BT_cxx_call_undef) 262239462Sdim BT_cxx_call_undef.reset(new BuiltinBug("Called C++ object pointer is " 263239462Sdim "uninitialized")); 264239462Sdim emitBadCall(BT_cxx_call_undef.get(), C, CC->getCXXThisExpr()); 265239462Sdim return; 266239462Sdim } 267218887Sdim 268239462Sdim ProgramStateRef StNonNull, StNull; 269249423Sdim llvm::tie(StNonNull, StNull) = 270249423Sdim State->assume(V.castAs<DefinedOrUnknownSVal>()); 271239462Sdim 272239462Sdim if (StNull && !StNonNull) { 273239462Sdim if (!BT_cxx_call_null) 274239462Sdim BT_cxx_call_null.reset(new BuiltinBug("Called C++ object pointer " 275239462Sdim "is null")); 276239462Sdim emitBadCall(BT_cxx_call_null.get(), C, CC->getCXXThisExpr()); 277218887Sdim return; 278218887Sdim } 279239462Sdim 280239462Sdim State = StNonNull; 281221345Sdim } 282218887Sdim 283239462Sdim // Don't check for uninitialized field values in arguments if the 284239462Sdim // caller has a body that is available and we have the chance to inline it. 285239462Sdim // This is a hack, but is a reasonable compromise betweens sometimes warning 286239462Sdim // and sometimes not depending on if we decide to inline a function. 287239462Sdim const Decl *D = Call.getDecl(); 288239462Sdim const bool checkUninitFields = 289239462Sdim !(C.getAnalysisManager().shouldInlineCall() && (D && D->getBody())); 290239462Sdim 291239462Sdim OwningPtr<BugType> *BT; 292239462Sdim if (isa<ObjCMethodCall>(Call)) 293239462Sdim BT = &BT_msg_arg; 294239462Sdim else 295239462Sdim BT = &BT_call_arg; 296239462Sdim 297239462Sdim for (unsigned i = 0, e = Call.getNumArgs(); i != e; ++i) 298239462Sdim if (PreVisitProcessArg(C, Call.getArgSVal(i), Call.getArgSourceRange(i), 299239462Sdim Call.getArgExpr(i), /*IsFirstArgument=*/i == 0, 300239462Sdim checkUninitFields, Call, *BT)) 301239462Sdim return; 302239462Sdim 303239462Sdim // If we make it here, record our assumptions about the callee. 304239462Sdim C.addTransition(State); 305218887Sdim} 306218887Sdim 307239462Sdimvoid CallAndMessageChecker::checkPreObjCMessage(const ObjCMethodCall &msg, 308239462Sdim CheckerContext &C) const { 309239462Sdim SVal recVal = msg.getReceiverSVal(); 310239462Sdim if (recVal.isUndef()) { 311239462Sdim if (ExplodedNode *N = C.generateSink()) { 312239462Sdim BugType *BT = 0; 313239462Sdim switch (msg.getMessageKind()) { 314239462Sdim case OCM_Message: 315239462Sdim if (!BT_msg_undef) 316239462Sdim BT_msg_undef.reset(new BuiltinBug("Receiver in message expression " 317239462Sdim "is an uninitialized value")); 318239462Sdim BT = BT_msg_undef.get(); 319239462Sdim break; 320239462Sdim case OCM_PropertyAccess: 321239462Sdim if (!BT_objc_prop_undef) 322239462Sdim BT_objc_prop_undef.reset(new BuiltinBug("Property access on an " 323239462Sdim "uninitialized object " 324239462Sdim "pointer")); 325239462Sdim BT = BT_objc_prop_undef.get(); 326239462Sdim break; 327239462Sdim case OCM_Subscript: 328239462Sdim if (!BT_objc_subscript_undef) 329239462Sdim BT_objc_subscript_undef.reset(new BuiltinBug("Subscript access on an " 330239462Sdim "uninitialized object " 331239462Sdim "pointer")); 332239462Sdim BT = BT_objc_subscript_undef.get(); 333239462Sdim break; 334239462Sdim } 335239462Sdim assert(BT && "Unknown message kind."); 336239462Sdim 337239462Sdim BugReport *R = new BugReport(*BT, BT->getName(), N); 338239462Sdim const ObjCMessageExpr *ME = msg.getOriginExpr(); 339239462Sdim R->addRange(ME->getReceiverRange()); 340239462Sdim 341239462Sdim // FIXME: getTrackNullOrUndefValueVisitor can't handle "super" yet. 342239462Sdim if (const Expr *ReceiverE = ME->getInstanceReceiver()) 343243830Sdim bugreporter::trackNullOrUndefValue(N, ReceiverE, *R); 344243830Sdim C.emitReport(R); 345239462Sdim } 346239462Sdim return; 347239462Sdim } else { 348239462Sdim // Bifurcate the state into nil and non-nil ones. 349249423Sdim DefinedOrUnknownSVal receiverVal = recVal.castAs<DefinedOrUnknownSVal>(); 350239462Sdim 351239462Sdim ProgramStateRef state = C.getState(); 352239462Sdim ProgramStateRef notNilState, nilState; 353239462Sdim llvm::tie(notNilState, nilState) = state->assume(receiverVal); 354239462Sdim 355239462Sdim // Handle receiver must be nil. 356239462Sdim if (nilState && !notNilState) { 357239462Sdim HandleNilReceiver(C, state, msg); 358239462Sdim return; 359239462Sdim } 360239462Sdim } 361239462Sdim} 362239462Sdim 363218887Sdimvoid CallAndMessageChecker::emitNilReceiverBug(CheckerContext &C, 364239462Sdim const ObjCMethodCall &msg, 365221345Sdim ExplodedNode *N) const { 366218887Sdim 367218887Sdim if (!BT_msg_ret) 368221345Sdim BT_msg_ret.reset( 369249423Sdim new BuiltinBug("Receiver in message expression is 'nil'")); 370218887Sdim 371239462Sdim const ObjCMessageExpr *ME = msg.getOriginExpr(); 372239462Sdim 373249423Sdim QualType ResTy = msg.getResultType(); 374249423Sdim 375234353Sdim SmallString<200> buf; 376218887Sdim llvm::raw_svector_ostream os(buf); 377239462Sdim os << "The receiver of message '" << ME->getSelector().getAsString() 378249423Sdim << "' is nil"; 379249423Sdim if (ResTy->isReferenceType()) { 380249423Sdim os << ", which results in forming a null reference"; 381249423Sdim } else { 382249423Sdim os << " and returns a value of type '"; 383249423Sdim msg.getResultType().print(os, C.getLangOpts()); 384249423Sdim os << "' that will be garbage"; 385249423Sdim } 386218887Sdim 387226633Sdim BugReport *report = new BugReport(*BT_msg_ret, os.str(), N); 388239462Sdim report->addRange(ME->getReceiverRange()); 389239462Sdim // FIXME: This won't track "self" in messages to super. 390239462Sdim if (const Expr *receiver = ME->getInstanceReceiver()) { 391243830Sdim bugreporter::trackNullOrUndefValue(N, receiver, *report); 392218887Sdim } 393243830Sdim C.emitReport(report); 394218887Sdim} 395218887Sdim 396218887Sdimstatic bool supportsNilWithFloatRet(const llvm::Triple &triple) { 397234353Sdim return (triple.getVendor() == llvm::Triple::Apple && 398234353Sdim (triple.getOS() == llvm::Triple::IOS || 399234353Sdim !triple.isMacOSXVersionLT(10,5))); 400218887Sdim} 401218887Sdim 402218887Sdimvoid CallAndMessageChecker::HandleNilReceiver(CheckerContext &C, 403234353Sdim ProgramStateRef state, 404239462Sdim const ObjCMethodCall &Msg) const { 405218887Sdim ASTContext &Ctx = C.getASTContext(); 406249423Sdim static SimpleProgramPointTag Tag("CallAndMessageChecker : NilReceiver"); 407218887Sdim 408218887Sdim // Check the return type of the message expression. A message to nil will 409218887Sdim // return different values depending on the return type and the architecture. 410239462Sdim QualType RetTy = Msg.getResultType(); 411218887Sdim CanQualType CanRetTy = Ctx.getCanonicalType(RetTy); 412234353Sdim const LocationContext *LCtx = C.getLocationContext(); 413218887Sdim 414218887Sdim if (CanRetTy->isStructureOrClassType()) { 415234353Sdim // Structure returns are safe since the compiler zeroes them out. 416239462Sdim SVal V = C.getSValBuilder().makeZeroVal(RetTy); 417249423Sdim C.addTransition(state->BindExpr(Msg.getOriginExpr(), LCtx, V), &Tag); 418218887Sdim return; 419218887Sdim } 420218887Sdim 421234353Sdim // Other cases: check if sizeof(return type) > sizeof(void*) 422234353Sdim if (CanRetTy != Ctx.VoidTy && C.getLocationContext()->getParentMap() 423239462Sdim .isConsumedExpr(Msg.getOriginExpr())) { 424218887Sdim // Compute: sizeof(void *) and sizeof(return type) 425218887Sdim const uint64_t voidPtrSize = Ctx.getTypeSize(Ctx.VoidPtrTy); 426218887Sdim const uint64_t returnTypeSize = Ctx.getTypeSize(CanRetTy); 427218887Sdim 428249423Sdim if (CanRetTy.getTypePtr()->isReferenceType()|| 429249423Sdim (voidPtrSize < returnTypeSize && 430249423Sdim !(supportsNilWithFloatRet(Ctx.getTargetInfo().getTriple()) && 431249423Sdim (Ctx.FloatTy == CanRetTy || 432249423Sdim Ctx.DoubleTy == CanRetTy || 433249423Sdim Ctx.LongDoubleTy == CanRetTy || 434249423Sdim Ctx.LongLongTy == CanRetTy || 435249423Sdim Ctx.UnsignedLongLongTy == CanRetTy)))) { 436249423Sdim if (ExplodedNode *N = C.generateSink(state, 0 , &Tag)) 437239462Sdim emitNilReceiverBug(C, Msg, N); 438218887Sdim return; 439218887Sdim } 440218887Sdim 441218887Sdim // Handle the safe cases where the return value is 0 if the 442218887Sdim // receiver is nil. 443218887Sdim // 444218887Sdim // FIXME: For now take the conservative approach that we only 445218887Sdim // return null values if we *know* that the receiver is nil. 446218887Sdim // This is because we can have surprises like: 447218887Sdim // 448218887Sdim // ... = [[NSScreens screens] objectAtIndex:0]; 449218887Sdim // 450218887Sdim // What can happen is that [... screens] could return nil, but 451218887Sdim // it most likely isn't nil. We should assume the semantics 452218887Sdim // of this case unless we have *a lot* more knowledge. 453218887Sdim // 454239462Sdim SVal V = C.getSValBuilder().makeZeroVal(RetTy); 455249423Sdim C.addTransition(state->BindExpr(Msg.getOriginExpr(), LCtx, V), &Tag); 456218887Sdim return; 457218887Sdim } 458218887Sdim 459218887Sdim C.addTransition(state); 460218887Sdim} 461221345Sdim 462221345Sdimvoid ento::registerCallAndMessageChecker(CheckerManager &mgr) { 463221345Sdim mgr.registerChecker<CallAndMessageChecker>(); 464221345Sdim} 465