MallocChecker.cpp revision 76aadc346c3a4c363238a1e1232f324c3355d9e0
1//=== MallocChecker.cpp - A malloc/free checker -------------------*- C++ -*--// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file defines malloc/free checker, which checks for potential memory 11// leaks, double free, and use-after-free problems. 12// 13//===----------------------------------------------------------------------===// 14 15#include "ClangSACheckers.h" 16#include "InterCheckerAPI.h" 17#include "clang/StaticAnalyzer/Core/Checker.h" 18#include "clang/StaticAnalyzer/Core/CheckerManager.h" 19#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 20#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" 21#include "clang/StaticAnalyzer/Core/PathSensitive/ObjCMessage.h" 22#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" 23#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h" 24#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h" 25#include "clang/Basic/SourceManager.h" 26#include "llvm/ADT/ImmutableMap.h" 27#include "llvm/ADT/SmallString.h" 28#include "llvm/ADT/STLExtras.h" 29#include <climits> 30 31using namespace clang; 32using namespace ento; 33 34namespace { 35 36class RefState { 37 enum Kind { AllocateUnchecked, AllocateFailed, Released, Escaped, 38 Relinquished } K; 39 const Stmt *S; 40 41public: 42 RefState(Kind k, const Stmt *s) : K(k), S(s) {} 43 44 bool isAllocated() const { return K == AllocateUnchecked; } 45 bool isReleased() const { return K == Released; } 46 47 const Stmt *getStmt() const { return S; } 48 49 bool operator==(const RefState &X) const { 50 return K == X.K && S == X.S; 51 } 52 53 static RefState getAllocateUnchecked(const Stmt *s) { 54 return RefState(AllocateUnchecked, s); 55 } 56 static RefState getAllocateFailed() { 57 return RefState(AllocateFailed, 0); 58 } 59 static RefState getReleased(const Stmt *s) { return RefState(Released, s); } 60 static RefState getEscaped(const Stmt *s) { return RefState(Escaped, s); } 61 static RefState getRelinquished(const Stmt *s) { 62 return RefState(Relinquished, s); 63 } 64 65 void Profile(llvm::FoldingSetNodeID &ID) const { 66 ID.AddInteger(K); 67 ID.AddPointer(S); 68 } 69}; 70 71struct ReallocPair { 72 SymbolRef ReallocatedSym; 73 bool IsFreeOnFailure; 74 ReallocPair(SymbolRef S, bool F) : ReallocatedSym(S), IsFreeOnFailure(F) {} 75 void Profile(llvm::FoldingSetNodeID &ID) const { 76 ID.AddInteger(IsFreeOnFailure); 77 ID.AddPointer(ReallocatedSym); 78 } 79 bool operator==(const ReallocPair &X) const { 80 return ReallocatedSym == X.ReallocatedSym && 81 IsFreeOnFailure == X.IsFreeOnFailure; 82 } 83}; 84 85class MallocChecker : public Checker<check::DeadSymbols, 86 check::EndPath, 87 check::PreStmt<ReturnStmt>, 88 check::PreStmt<CallExpr>, 89 check::PostStmt<CallExpr>, 90 check::Location, 91 check::Bind, 92 eval::Assume, 93 check::RegionChanges> 94{ 95 mutable OwningPtr<BugType> BT_DoubleFree; 96 mutable OwningPtr<BugType> BT_Leak; 97 mutable OwningPtr<BugType> BT_UseFree; 98 mutable OwningPtr<BugType> BT_BadFree; 99 mutable IdentifierInfo *II_malloc, *II_free, *II_realloc, *II_calloc, 100 *II_valloc, *II_reallocf, *II_strndup, *II_strdup; 101 102public: 103 MallocChecker() : II_malloc(0), II_free(0), II_realloc(0), II_calloc(0), 104 II_valloc(0), II_reallocf(0), II_strndup(0), II_strdup(0) {} 105 106 /// In pessimistic mode, the checker assumes that it does not know which 107 /// functions might free the memory. 108 struct ChecksFilter { 109 DefaultBool CMallocPessimistic; 110 DefaultBool CMallocOptimistic; 111 }; 112 113 ChecksFilter Filter; 114 115 void checkPreStmt(const CallExpr *S, CheckerContext &C) const; 116 void checkPostStmt(const CallExpr *CE, CheckerContext &C) const; 117 void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const; 118 void checkEndPath(CheckerContext &C) const; 119 void checkPreStmt(const ReturnStmt *S, CheckerContext &C) const; 120 ProgramStateRef evalAssume(ProgramStateRef state, SVal Cond, 121 bool Assumption) const; 122 void checkLocation(SVal l, bool isLoad, const Stmt *S, 123 CheckerContext &C) const; 124 void checkBind(SVal location, SVal val, const Stmt*S, 125 CheckerContext &C) const; 126 ProgramStateRef 127 checkRegionChanges(ProgramStateRef state, 128 const StoreManager::InvalidatedSymbols *invalidated, 129 ArrayRef<const MemRegion *> ExplicitRegions, 130 ArrayRef<const MemRegion *> Regions, 131 const CallOrObjCMessage *Call) const; 132 bool wantsRegionChangeUpdate(ProgramStateRef state) const { 133 return true; 134 } 135 136private: 137 void initIdentifierInfo(ASTContext &C) const; 138 139 /// Check if this is one of the functions which can allocate/reallocate memory 140 /// pointed to by one of its arguments. 141 bool isMemFunction(const FunctionDecl *FD, ASTContext &C) const; 142 143 static ProgramStateRef MallocMemReturnsAttr(CheckerContext &C, 144 const CallExpr *CE, 145 const OwnershipAttr* Att); 146 static ProgramStateRef MallocMemAux(CheckerContext &C, const CallExpr *CE, 147 const Expr *SizeEx, SVal Init, 148 ProgramStateRef state) { 149 return MallocMemAux(C, CE, 150 state->getSVal(SizeEx, C.getLocationContext()), 151 Init, state); 152 } 153 154 static ProgramStateRef MallocMemAux(CheckerContext &C, const CallExpr *CE, 155 SVal SizeEx, SVal Init, 156 ProgramStateRef state); 157 158 /// Update the RefState to reflect the new memory allocation. 159 static ProgramStateRef MallocUpdateRefState(CheckerContext &C, 160 const CallExpr *CE, 161 ProgramStateRef state); 162 163 ProgramStateRef FreeMemAttr(CheckerContext &C, const CallExpr *CE, 164 const OwnershipAttr* Att) const; 165 ProgramStateRef FreeMemAux(CheckerContext &C, const CallExpr *CE, 166 ProgramStateRef state, unsigned Num, 167 bool Hold) const; 168 169 ProgramStateRef ReallocMem(CheckerContext &C, const CallExpr *CE, 170 bool FreesMemOnFailure) const; 171 static ProgramStateRef CallocMem(CheckerContext &C, const CallExpr *CE); 172 173 bool checkEscape(SymbolRef Sym, const Stmt *S, CheckerContext &C) const; 174 bool checkUseAfterFree(SymbolRef Sym, CheckerContext &C, 175 const Stmt *S = 0) const; 176 177 /// Check if the function is not known to us. So, for example, we could 178 /// conservatively assume it can free/reallocate it's pointer arguments. 179 bool doesNotFreeMemory(const CallOrObjCMessage *Call, 180 ProgramStateRef State) const; 181 182 static bool SummarizeValue(raw_ostream &os, SVal V); 183 static bool SummarizeRegion(raw_ostream &os, const MemRegion *MR); 184 void ReportBadFree(CheckerContext &C, SVal ArgVal, SourceRange range) const; 185 186 /// Find the location of the allocation for Sym on the path leading to the 187 /// exploded node N. 188 const Stmt *getAllocationSite(const ExplodedNode *N, SymbolRef Sym, 189 CheckerContext &C) const; 190 191 void reportLeak(SymbolRef Sym, ExplodedNode *N, CheckerContext &C) const; 192 193 /// The bug visitor which allows us to print extra diagnostics along the 194 /// BugReport path. For example, showing the allocation site of the leaked 195 /// region. 196 class MallocBugVisitor : public BugReporterVisitor { 197 protected: 198 enum NotificationMode { 199 Normal, 200 Complete, 201 ReallocationFailed 202 }; 203 204 // The allocated region symbol tracked by the main analysis. 205 SymbolRef Sym; 206 NotificationMode Mode; 207 208 public: 209 MallocBugVisitor(SymbolRef S) : Sym(S), Mode(Normal) {} 210 virtual ~MallocBugVisitor() {} 211 212 void Profile(llvm::FoldingSetNodeID &ID) const { 213 static int X = 0; 214 ID.AddPointer(&X); 215 ID.AddPointer(Sym); 216 } 217 218 inline bool isAllocated(const RefState *S, const RefState *SPrev, 219 const Stmt *Stmt) { 220 // Did not track -> allocated. Other state (released) -> allocated. 221 return (Stmt && isa<CallExpr>(Stmt) && 222 (S && S->isAllocated()) && (!SPrev || !SPrev->isAllocated())); 223 } 224 225 inline bool isReleased(const RefState *S, const RefState *SPrev, 226 const Stmt *Stmt) { 227 // Did not track -> released. Other state (allocated) -> released. 228 return (Stmt && isa<CallExpr>(Stmt) && 229 (S && S->isReleased()) && (!SPrev || !SPrev->isReleased())); 230 } 231 232 inline bool isReallocFailedCheck(const RefState *S, const RefState *SPrev, 233 const Stmt *Stmt) { 234 // If the expression is not a call, and the state change is 235 // released -> allocated, it must be the realloc return value 236 // check. If we have to handle more cases here, it might be cleaner just 237 // to track this extra bit in the state itself. 238 return ((!Stmt || !isa<CallExpr>(Stmt)) && 239 (S && S->isAllocated()) && (SPrev && !SPrev->isAllocated())); 240 } 241 242 PathDiagnosticPiece *VisitNode(const ExplodedNode *N, 243 const ExplodedNode *PrevN, 244 BugReporterContext &BRC, 245 BugReport &BR); 246 }; 247}; 248} // end anonymous namespace 249 250typedef llvm::ImmutableMap<SymbolRef, RefState> RegionStateTy; 251typedef llvm::ImmutableMap<SymbolRef, ReallocPair > ReallocMap; 252class RegionState {}; 253class ReallocPairs {}; 254namespace clang { 255namespace ento { 256 template <> 257 struct ProgramStateTrait<RegionState> 258 : public ProgramStatePartialTrait<RegionStateTy> { 259 static void *GDMIndex() { static int x; return &x; } 260 }; 261 262 template <> 263 struct ProgramStateTrait<ReallocPairs> 264 : public ProgramStatePartialTrait<ReallocMap> { 265 static void *GDMIndex() { static int x; return &x; } 266 }; 267} 268} 269 270namespace { 271class StopTrackingCallback : public SymbolVisitor { 272 ProgramStateRef state; 273public: 274 StopTrackingCallback(ProgramStateRef st) : state(st) {} 275 ProgramStateRef getState() const { return state; } 276 277 bool VisitSymbol(SymbolRef sym) { 278 state = state->remove<RegionState>(sym); 279 return true; 280 } 281}; 282} // end anonymous namespace 283 284void MallocChecker::initIdentifierInfo(ASTContext &Ctx) const { 285 if (!II_malloc) 286 II_malloc = &Ctx.Idents.get("malloc"); 287 if (!II_free) 288 II_free = &Ctx.Idents.get("free"); 289 if (!II_realloc) 290 II_realloc = &Ctx.Idents.get("realloc"); 291 if (!II_reallocf) 292 II_reallocf = &Ctx.Idents.get("reallocf"); 293 if (!II_calloc) 294 II_calloc = &Ctx.Idents.get("calloc"); 295 if (!II_valloc) 296 II_valloc = &Ctx.Idents.get("valloc"); 297 if (!II_strdup) 298 II_strdup = &Ctx.Idents.get("strdup"); 299 if (!II_strndup) 300 II_strndup = &Ctx.Idents.get("strndup"); 301} 302 303bool MallocChecker::isMemFunction(const FunctionDecl *FD, ASTContext &C) const { 304 if (!FD) 305 return false; 306 IdentifierInfo *FunI = FD->getIdentifier(); 307 if (!FunI) 308 return false; 309 310 initIdentifierInfo(C); 311 312 if (FunI == II_malloc || FunI == II_free || FunI == II_realloc || 313 FunI == II_reallocf || FunI == II_calloc || FunI == II_valloc || 314 FunI == II_strdup || FunI == II_strndup) 315 return true; 316 317 if (Filter.CMallocOptimistic && FD->hasAttrs() && 318 FD->specific_attr_begin<OwnershipAttr>() != 319 FD->specific_attr_end<OwnershipAttr>()) 320 return true; 321 322 323 return false; 324} 325 326void MallocChecker::checkPostStmt(const CallExpr *CE, CheckerContext &C) const { 327 const FunctionDecl *FD = C.getCalleeDecl(CE); 328 if (!FD) 329 return; 330 331 initIdentifierInfo(C.getASTContext()); 332 IdentifierInfo *FunI = FD->getIdentifier(); 333 if (!FunI) 334 return; 335 336 ProgramStateRef State = C.getState(); 337 if (FunI == II_malloc || FunI == II_valloc) { 338 State = MallocMemAux(C, CE, CE->getArg(0), UndefinedVal(), State); 339 } else if (FunI == II_realloc) { 340 State = ReallocMem(C, CE, false); 341 } else if (FunI == II_reallocf) { 342 State = ReallocMem(C, CE, true); 343 } else if (FunI == II_calloc) { 344 State = CallocMem(C, CE); 345 } else if (FunI == II_free) { 346 State = FreeMemAux(C, CE, C.getState(), 0, false); 347 } else if (FunI == II_strdup) { 348 State = MallocUpdateRefState(C, CE, State); 349 } else if (FunI == II_strndup) { 350 State = MallocUpdateRefState(C, CE, State); 351 } else if (Filter.CMallocOptimistic) { 352 // Check all the attributes, if there are any. 353 // There can be multiple of these attributes. 354 if (FD->hasAttrs()) 355 for (specific_attr_iterator<OwnershipAttr> 356 i = FD->specific_attr_begin<OwnershipAttr>(), 357 e = FD->specific_attr_end<OwnershipAttr>(); 358 i != e; ++i) { 359 switch ((*i)->getOwnKind()) { 360 case OwnershipAttr::Returns: 361 State = MallocMemReturnsAttr(C, CE, *i); 362 break; 363 case OwnershipAttr::Takes: 364 case OwnershipAttr::Holds: 365 State = FreeMemAttr(C, CE, *i); 366 break; 367 } 368 } 369 } 370 C.addTransition(State); 371} 372 373ProgramStateRef MallocChecker::MallocMemReturnsAttr(CheckerContext &C, 374 const CallExpr *CE, 375 const OwnershipAttr* Att) { 376 if (Att->getModule() != "malloc") 377 return 0; 378 379 OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end(); 380 if (I != E) { 381 return MallocMemAux(C, CE, CE->getArg(*I), UndefinedVal(), C.getState()); 382 } 383 return MallocMemAux(C, CE, UnknownVal(), UndefinedVal(), C.getState()); 384} 385 386ProgramStateRef MallocChecker::MallocMemAux(CheckerContext &C, 387 const CallExpr *CE, 388 SVal Size, SVal Init, 389 ProgramStateRef state) { 390 // Get the return value. 391 SVal retVal = state->getSVal(CE, C.getLocationContext()); 392 393 // We expect the malloc functions to return a pointer. 394 if (!isa<Loc>(retVal)) 395 return 0; 396 397 // Fill the region with the initialization value. 398 state = state->bindDefault(retVal, Init); 399 400 // Set the region's extent equal to the Size parameter. 401 const SymbolicRegion *R = 402 dyn_cast_or_null<SymbolicRegion>(retVal.getAsRegion()); 403 if (!R) 404 return 0; 405 if (isa<DefinedOrUnknownSVal>(Size)) { 406 SValBuilder &svalBuilder = C.getSValBuilder(); 407 DefinedOrUnknownSVal Extent = R->getExtent(svalBuilder); 408 DefinedOrUnknownSVal DefinedSize = cast<DefinedOrUnknownSVal>(Size); 409 DefinedOrUnknownSVal extentMatchesSize = 410 svalBuilder.evalEQ(state, Extent, DefinedSize); 411 412 state = state->assume(extentMatchesSize, true); 413 assert(state); 414 } 415 416 return MallocUpdateRefState(C, CE, state); 417} 418 419ProgramStateRef MallocChecker::MallocUpdateRefState(CheckerContext &C, 420 const CallExpr *CE, 421 ProgramStateRef state) { 422 // Get the return value. 423 SVal retVal = state->getSVal(CE, C.getLocationContext()); 424 425 // We expect the malloc functions to return a pointer. 426 if (!isa<Loc>(retVal)) 427 return 0; 428 429 SymbolRef Sym = retVal.getAsLocSymbol(); 430 assert(Sym); 431 432 // Set the symbol's state to Allocated. 433 return state->set<RegionState>(Sym, RefState::getAllocateUnchecked(CE)); 434 435} 436 437ProgramStateRef MallocChecker::FreeMemAttr(CheckerContext &C, 438 const CallExpr *CE, 439 const OwnershipAttr* Att) const { 440 if (Att->getModule() != "malloc") 441 return 0; 442 443 ProgramStateRef State = C.getState(); 444 445 for (OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end(); 446 I != E; ++I) { 447 ProgramStateRef StateI = FreeMemAux(C, CE, State, *I, 448 Att->getOwnKind() == OwnershipAttr::Holds); 449 if (StateI) 450 State = StateI; 451 } 452 return State; 453} 454 455ProgramStateRef MallocChecker::FreeMemAux(CheckerContext &C, 456 const CallExpr *CE, 457 ProgramStateRef state, 458 unsigned Num, 459 bool Hold) const { 460 const Expr *ArgExpr = CE->getArg(Num); 461 SVal ArgVal = state->getSVal(ArgExpr, C.getLocationContext()); 462 if (!isa<DefinedOrUnknownSVal>(ArgVal)) 463 return 0; 464 DefinedOrUnknownSVal location = cast<DefinedOrUnknownSVal>(ArgVal); 465 466 // Check for null dereferences. 467 if (!isa<Loc>(location)) 468 return 0; 469 470 // The explicit NULL case, no operation is performed. 471 ProgramStateRef notNullState, nullState; 472 llvm::tie(notNullState, nullState) = state->assume(location); 473 if (nullState && !notNullState) 474 return 0; 475 476 // Unknown values could easily be okay 477 // Undefined values are handled elsewhere 478 if (ArgVal.isUnknownOrUndef()) 479 return 0; 480 481 const MemRegion *R = ArgVal.getAsRegion(); 482 483 // Nonlocs can't be freed, of course. 484 // Non-region locations (labels and fixed addresses) also shouldn't be freed. 485 if (!R) { 486 ReportBadFree(C, ArgVal, ArgExpr->getSourceRange()); 487 return 0; 488 } 489 490 R = R->StripCasts(); 491 492 // Blocks might show up as heap data, but should not be free()d 493 if (isa<BlockDataRegion>(R)) { 494 ReportBadFree(C, ArgVal, ArgExpr->getSourceRange()); 495 return 0; 496 } 497 498 const MemSpaceRegion *MS = R->getMemorySpace(); 499 500 // Parameters, locals, statics, and globals shouldn't be freed. 501 if (!(isa<UnknownSpaceRegion>(MS) || isa<HeapSpaceRegion>(MS))) { 502 // FIXME: at the time this code was written, malloc() regions were 503 // represented by conjured symbols, which are all in UnknownSpaceRegion. 504 // This means that there isn't actually anything from HeapSpaceRegion 505 // that should be freed, even though we allow it here. 506 // Of course, free() can work on memory allocated outside the current 507 // function, so UnknownSpaceRegion is always a possibility. 508 // False negatives are better than false positives. 509 510 ReportBadFree(C, ArgVal, ArgExpr->getSourceRange()); 511 return 0; 512 } 513 514 const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R); 515 // Various cases could lead to non-symbol values here. 516 // For now, ignore them. 517 if (!SR) 518 return 0; 519 520 SymbolRef Sym = SR->getSymbol(); 521 const RefState *RS = state->get<RegionState>(Sym); 522 523 // If the symbol has not been tracked, return. This is possible when free() is 524 // called on a pointer that does not get its pointee directly from malloc(). 525 // Full support of this requires inter-procedural analysis. 526 if (!RS) 527 return 0; 528 529 // Check double free. 530 if (RS->isReleased()) { 531 if (ExplodedNode *N = C.generateSink()) { 532 if (!BT_DoubleFree) 533 BT_DoubleFree.reset( 534 new BugType("Double free", "Memory Error")); 535 BugReport *R = new BugReport(*BT_DoubleFree, 536 "Attempt to free released memory", N); 537 R->addRange(ArgExpr->getSourceRange()); 538 R->markInteresting(Sym); 539 R->addVisitor(new MallocBugVisitor(Sym)); 540 C.EmitReport(R); 541 } 542 return 0; 543 } 544 545 // Normal free. 546 if (Hold) 547 return state->set<RegionState>(Sym, RefState::getRelinquished(CE)); 548 return state->set<RegionState>(Sym, RefState::getReleased(CE)); 549} 550 551bool MallocChecker::SummarizeValue(raw_ostream &os, SVal V) { 552 if (nonloc::ConcreteInt *IntVal = dyn_cast<nonloc::ConcreteInt>(&V)) 553 os << "an integer (" << IntVal->getValue() << ")"; 554 else if (loc::ConcreteInt *ConstAddr = dyn_cast<loc::ConcreteInt>(&V)) 555 os << "a constant address (" << ConstAddr->getValue() << ")"; 556 else if (loc::GotoLabel *Label = dyn_cast<loc::GotoLabel>(&V)) 557 os << "the address of the label '" << Label->getLabel()->getName() << "'"; 558 else 559 return false; 560 561 return true; 562} 563 564bool MallocChecker::SummarizeRegion(raw_ostream &os, 565 const MemRegion *MR) { 566 switch (MR->getKind()) { 567 case MemRegion::FunctionTextRegionKind: { 568 const FunctionDecl *FD = cast<FunctionTextRegion>(MR)->getDecl(); 569 if (FD) 570 os << "the address of the function '" << *FD << '\''; 571 else 572 os << "the address of a function"; 573 return true; 574 } 575 case MemRegion::BlockTextRegionKind: 576 os << "block text"; 577 return true; 578 case MemRegion::BlockDataRegionKind: 579 // FIXME: where the block came from? 580 os << "a block"; 581 return true; 582 default: { 583 const MemSpaceRegion *MS = MR->getMemorySpace(); 584 585 if (isa<StackLocalsSpaceRegion>(MS)) { 586 const VarRegion *VR = dyn_cast<VarRegion>(MR); 587 const VarDecl *VD; 588 if (VR) 589 VD = VR->getDecl(); 590 else 591 VD = NULL; 592 593 if (VD) 594 os << "the address of the local variable '" << VD->getName() << "'"; 595 else 596 os << "the address of a local stack variable"; 597 return true; 598 } 599 600 if (isa<StackArgumentsSpaceRegion>(MS)) { 601 const VarRegion *VR = dyn_cast<VarRegion>(MR); 602 const VarDecl *VD; 603 if (VR) 604 VD = VR->getDecl(); 605 else 606 VD = NULL; 607 608 if (VD) 609 os << "the address of the parameter '" << VD->getName() << "'"; 610 else 611 os << "the address of a parameter"; 612 return true; 613 } 614 615 if (isa<GlobalsSpaceRegion>(MS)) { 616 const VarRegion *VR = dyn_cast<VarRegion>(MR); 617 const VarDecl *VD; 618 if (VR) 619 VD = VR->getDecl(); 620 else 621 VD = NULL; 622 623 if (VD) { 624 if (VD->isStaticLocal()) 625 os << "the address of the static variable '" << VD->getName() << "'"; 626 else 627 os << "the address of the global variable '" << VD->getName() << "'"; 628 } else 629 os << "the address of a global variable"; 630 return true; 631 } 632 633 return false; 634 } 635 } 636} 637 638void MallocChecker::ReportBadFree(CheckerContext &C, SVal ArgVal, 639 SourceRange range) const { 640 if (ExplodedNode *N = C.generateSink()) { 641 if (!BT_BadFree) 642 BT_BadFree.reset(new BugType("Bad free", "Memory Error")); 643 644 SmallString<100> buf; 645 llvm::raw_svector_ostream os(buf); 646 647 const MemRegion *MR = ArgVal.getAsRegion(); 648 if (MR) { 649 while (const ElementRegion *ER = dyn_cast<ElementRegion>(MR)) 650 MR = ER->getSuperRegion(); 651 652 // Special case for alloca() 653 if (isa<AllocaRegion>(MR)) 654 os << "Argument to free() was allocated by alloca(), not malloc()"; 655 else { 656 os << "Argument to free() is "; 657 if (SummarizeRegion(os, MR)) 658 os << ", which is not memory allocated by malloc()"; 659 else 660 os << "not memory allocated by malloc()"; 661 } 662 } else { 663 os << "Argument to free() is "; 664 if (SummarizeValue(os, ArgVal)) 665 os << ", which is not memory allocated by malloc()"; 666 else 667 os << "not memory allocated by malloc()"; 668 } 669 670 BugReport *R = new BugReport(*BT_BadFree, os.str(), N); 671 R->markInteresting(MR); 672 R->addRange(range); 673 C.EmitReport(R); 674 } 675} 676 677ProgramStateRef MallocChecker::ReallocMem(CheckerContext &C, 678 const CallExpr *CE, 679 bool FreesOnFail) const { 680 ProgramStateRef state = C.getState(); 681 const Expr *arg0Expr = CE->getArg(0); 682 const LocationContext *LCtx = C.getLocationContext(); 683 SVal Arg0Val = state->getSVal(arg0Expr, LCtx); 684 if (!isa<DefinedOrUnknownSVal>(Arg0Val)) 685 return 0; 686 DefinedOrUnknownSVal arg0Val = cast<DefinedOrUnknownSVal>(Arg0Val); 687 688 SValBuilder &svalBuilder = C.getSValBuilder(); 689 690 DefinedOrUnknownSVal PtrEQ = 691 svalBuilder.evalEQ(state, arg0Val, svalBuilder.makeNull()); 692 693 // Get the size argument. If there is no size arg then give up. 694 const Expr *Arg1 = CE->getArg(1); 695 if (!Arg1) 696 return 0; 697 698 // Get the value of the size argument. 699 SVal Arg1ValG = state->getSVal(Arg1, LCtx); 700 if (!isa<DefinedOrUnknownSVal>(Arg1ValG)) 701 return 0; 702 DefinedOrUnknownSVal Arg1Val = cast<DefinedOrUnknownSVal>(Arg1ValG); 703 704 // Compare the size argument to 0. 705 DefinedOrUnknownSVal SizeZero = 706 svalBuilder.evalEQ(state, Arg1Val, 707 svalBuilder.makeIntValWithPtrWidth(0, false)); 708 709 ProgramStateRef StatePtrIsNull, StatePtrNotNull; 710 llvm::tie(StatePtrIsNull, StatePtrNotNull) = state->assume(PtrEQ); 711 ProgramStateRef StateSizeIsZero, StateSizeNotZero; 712 llvm::tie(StateSizeIsZero, StateSizeNotZero) = state->assume(SizeZero); 713 // We only assume exceptional states if they are definitely true; if the 714 // state is under-constrained, assume regular realloc behavior. 715 bool PrtIsNull = StatePtrIsNull && !StatePtrNotNull; 716 bool SizeIsZero = StateSizeIsZero && !StateSizeNotZero; 717 718 // If the ptr is NULL and the size is not 0, the call is equivalent to 719 // malloc(size). 720 if ( PrtIsNull && !SizeIsZero) { 721 ProgramStateRef stateMalloc = MallocMemAux(C, CE, CE->getArg(1), 722 UndefinedVal(), StatePtrIsNull); 723 return stateMalloc; 724 } 725 726 if (PrtIsNull && SizeIsZero) 727 return 0; 728 729 // Get the from and to pointer symbols as in toPtr = realloc(fromPtr, size). 730 assert(!PrtIsNull); 731 SymbolRef FromPtr = arg0Val.getAsSymbol(); 732 SVal RetVal = state->getSVal(CE, LCtx); 733 SymbolRef ToPtr = RetVal.getAsSymbol(); 734 if (!FromPtr || !ToPtr) 735 return 0; 736 737 // If the size is 0, free the memory. 738 if (SizeIsZero) 739 if (ProgramStateRef stateFree = FreeMemAux(C, CE, StateSizeIsZero,0,false)){ 740 // The semantics of the return value are: 741 // If size was equal to 0, either NULL or a pointer suitable to be passed 742 // to free() is returned. 743 stateFree = stateFree->set<ReallocPairs>(ToPtr, 744 ReallocPair(FromPtr, FreesOnFail)); 745 C.getSymbolManager().addSymbolDependency(ToPtr, FromPtr); 746 return stateFree; 747 } 748 749 // Default behavior. 750 if (ProgramStateRef stateFree = FreeMemAux(C, CE, state, 0, false)) { 751 // FIXME: We should copy the content of the original buffer. 752 ProgramStateRef stateRealloc = MallocMemAux(C, CE, CE->getArg(1), 753 UnknownVal(), stateFree); 754 if (!stateRealloc) 755 return 0; 756 stateRealloc = stateRealloc->set<ReallocPairs>(ToPtr, 757 ReallocPair(FromPtr, FreesOnFail)); 758 C.getSymbolManager().addSymbolDependency(ToPtr, FromPtr); 759 return stateRealloc; 760 } 761 return 0; 762} 763 764ProgramStateRef MallocChecker::CallocMem(CheckerContext &C, const CallExpr *CE){ 765 ProgramStateRef state = C.getState(); 766 SValBuilder &svalBuilder = C.getSValBuilder(); 767 const LocationContext *LCtx = C.getLocationContext(); 768 SVal count = state->getSVal(CE->getArg(0), LCtx); 769 SVal elementSize = state->getSVal(CE->getArg(1), LCtx); 770 SVal TotalSize = svalBuilder.evalBinOp(state, BO_Mul, count, elementSize, 771 svalBuilder.getContext().getSizeType()); 772 SVal zeroVal = svalBuilder.makeZeroVal(svalBuilder.getContext().CharTy); 773 774 return MallocMemAux(C, CE, TotalSize, zeroVal, state); 775} 776 777const Stmt * 778MallocChecker::getAllocationSite(const ExplodedNode *N, SymbolRef Sym, 779 CheckerContext &C) const { 780 const LocationContext *LeakContext = N->getLocationContext(); 781 // Walk the ExplodedGraph backwards and find the first node that referred to 782 // the tracked symbol. 783 const ExplodedNode *AllocNode = N; 784 785 while (N) { 786 if (!N->getState()->get<RegionState>(Sym)) 787 break; 788 // Allocation node, is the last node in the current context in which the 789 // symbol was tracked. 790 if (N->getLocationContext() == LeakContext) 791 AllocNode = N; 792 N = N->pred_empty() ? NULL : *(N->pred_begin()); 793 } 794 795 ProgramPoint P = AllocNode->getLocation(); 796 if (!isa<StmtPoint>(P)) 797 return 0; 798 799 return cast<StmtPoint>(P).getStmt(); 800} 801 802void MallocChecker::reportLeak(SymbolRef Sym, ExplodedNode *N, 803 CheckerContext &C) const { 804 assert(N); 805 if (!BT_Leak) { 806 BT_Leak.reset(new BugType("Memory leak", "Memory Error")); 807 // Leaks should not be reported if they are post-dominated by a sink: 808 // (1) Sinks are higher importance bugs. 809 // (2) NoReturnFunctionChecker uses sink nodes to represent paths ending 810 // with __noreturn functions such as assert() or exit(). We choose not 811 // to report leaks on such paths. 812 BT_Leak->setSuppressOnSink(true); 813 } 814 815 // Most bug reports are cached at the location where they occurred. 816 // With leaks, we want to unique them by the location where they were 817 // allocated, and only report a single path. 818 PathDiagnosticLocation LocUsedForUniqueing; 819 if (const Stmt *AllocStmt = getAllocationSite(N, Sym, C)) 820 LocUsedForUniqueing = PathDiagnosticLocation::createBegin(AllocStmt, 821 C.getSourceManager(), N->getLocationContext()); 822 823 BugReport *R = new BugReport(*BT_Leak, 824 "Memory is never released; potential memory leak", N, LocUsedForUniqueing); 825 R->markInteresting(Sym); 826 R->addVisitor(new MallocBugVisitor(Sym)); 827 C.EmitReport(R); 828} 829 830void MallocChecker::checkDeadSymbols(SymbolReaper &SymReaper, 831 CheckerContext &C) const 832{ 833 if (!SymReaper.hasDeadSymbols()) 834 return; 835 836 ProgramStateRef state = C.getState(); 837 RegionStateTy RS = state->get<RegionState>(); 838 RegionStateTy::Factory &F = state->get_context<RegionState>(); 839 840 bool generateReport = false; 841 llvm::SmallVector<SymbolRef, 2> Errors; 842 for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) { 843 if (SymReaper.isDead(I->first)) { 844 if (I->second.isAllocated()) { 845 generateReport = true; 846 Errors.push_back(I->first); 847 } 848 // Remove the dead symbol from the map. 849 RS = F.remove(RS, I->first); 850 851 } 852 } 853 854 // Cleanup the Realloc Pairs Map. 855 ReallocMap RP = state->get<ReallocPairs>(); 856 for (ReallocMap::iterator I = RP.begin(), E = RP.end(); I != E; ++I) { 857 if (SymReaper.isDead(I->first) || 858 SymReaper.isDead(I->second.ReallocatedSym)) { 859 state = state->remove<ReallocPairs>(I->first); 860 } 861 } 862 863 // Generate leak node. 864 static SimpleProgramPointTag Tag("MallocChecker : DeadSymbolsLeak"); 865 ExplodedNode *N = C.addTransition(C.getState(), C.getPredecessor(), &Tag); 866 867 if (generateReport) { 868 for (llvm::SmallVector<SymbolRef, 2>::iterator 869 I = Errors.begin(), E = Errors.end(); I != E; ++I) { 870 reportLeak(*I, N, C); 871 } 872 } 873 C.addTransition(state->set<RegionState>(RS), N); 874} 875 876void MallocChecker::checkEndPath(CheckerContext &C) const { 877 ProgramStateRef state = C.getState(); 878 RegionStateTy M = state->get<RegionState>(); 879 880 // If inside inlined call, skip it. 881 if (C.getLocationContext()->getParent() != 0) 882 return; 883 884 for (RegionStateTy::iterator I = M.begin(), E = M.end(); I != E; ++I) { 885 RefState RS = I->second; 886 if (RS.isAllocated()) { 887 ExplodedNode *N = C.addTransition(state); 888 if (N) 889 reportLeak(I->first, N, C); 890 } 891 } 892} 893 894bool MallocChecker::checkEscape(SymbolRef Sym, const Stmt *S, 895 CheckerContext &C) const { 896 ProgramStateRef state = C.getState(); 897 const RefState *RS = state->get<RegionState>(Sym); 898 if (!RS) 899 return false; 900 901 if (RS->isAllocated()) { 902 state = state->set<RegionState>(Sym, RefState::getEscaped(S)); 903 C.addTransition(state); 904 return true; 905 } 906 return false; 907} 908 909void MallocChecker::checkPreStmt(const CallExpr *CE, CheckerContext &C) const { 910 if (isMemFunction(C.getCalleeDecl(CE), C.getASTContext())) 911 return; 912 913 // Check use after free, when a freed pointer is passed to a call. 914 ProgramStateRef State = C.getState(); 915 for (CallExpr::const_arg_iterator I = CE->arg_begin(), 916 E = CE->arg_end(); I != E; ++I) { 917 const Expr *A = *I; 918 if (A->getType().getTypePtr()->isAnyPointerType()) { 919 SymbolRef Sym = State->getSVal(A, C.getLocationContext()).getAsSymbol(); 920 if (!Sym) 921 continue; 922 if (checkUseAfterFree(Sym, C, A)) 923 return; 924 } 925 } 926} 927 928void MallocChecker::checkPreStmt(const ReturnStmt *S, CheckerContext &C) const { 929 const Expr *E = S->getRetValue(); 930 if (!E) 931 return; 932 933 // Check if we are returning a symbol. 934 SVal RetVal = C.getState()->getSVal(E, C.getLocationContext()); 935 SymbolRef Sym = RetVal.getAsSymbol(); 936 if (!Sym) 937 // If we are returning a field of the allocated struct or an array element, 938 // the callee could still free the memory. 939 // TODO: This logic should be a part of generic symbol escape callback. 940 if (const MemRegion *MR = RetVal.getAsRegion()) 941 if (isa<FieldRegion>(MR) || isa<ElementRegion>(MR)) 942 if (const SymbolicRegion *BMR = 943 dyn_cast<SymbolicRegion>(MR->getBaseRegion())) 944 Sym = BMR->getSymbol(); 945 if (!Sym) 946 return; 947 948 // Check if we are returning freed memory. 949 if (checkUseAfterFree(Sym, C, E)) 950 return; 951 952 // If this function body is not inlined, check if the symbol is escaping. 953 if (C.getLocationContext()->getParent() == 0) 954 checkEscape(Sym, E, C); 955} 956 957bool MallocChecker::checkUseAfterFree(SymbolRef Sym, CheckerContext &C, 958 const Stmt *S) const { 959 assert(Sym); 960 const RefState *RS = C.getState()->get<RegionState>(Sym); 961 if (RS && RS->isReleased()) { 962 if (ExplodedNode *N = C.generateSink()) { 963 if (!BT_UseFree) 964 BT_UseFree.reset(new BugType("Use-after-free", "Memory Error")); 965 966 BugReport *R = new BugReport(*BT_UseFree, 967 "Use of memory after it is freed",N); 968 if (S) 969 R->addRange(S->getSourceRange()); 970 R->markInteresting(Sym); 971 R->addVisitor(new MallocBugVisitor(Sym)); 972 C.EmitReport(R); 973 return true; 974 } 975 } 976 return false; 977} 978 979// Check if the location is a freed symbolic region. 980void MallocChecker::checkLocation(SVal l, bool isLoad, const Stmt *S, 981 CheckerContext &C) const { 982 SymbolRef Sym = l.getLocSymbolInBase(); 983 if (Sym) 984 checkUseAfterFree(Sym, C); 985} 986 987//===----------------------------------------------------------------------===// 988// Check various ways a symbol can be invalidated. 989// TODO: This logic (the next 3 functions) is copied/similar to the 990// RetainRelease checker. We might want to factor this out. 991//===----------------------------------------------------------------------===// 992 993// Stop tracking symbols when a value escapes as a result of checkBind. 994// A value escapes in three possible cases: 995// (1) we are binding to something that is not a memory region. 996// (2) we are binding to a memregion that does not have stack storage 997// (3) we are binding to a memregion with stack storage that the store 998// does not understand. 999void MallocChecker::checkBind(SVal loc, SVal val, const Stmt *S, 1000 CheckerContext &C) const { 1001 // Are we storing to something that causes the value to "escape"? 1002 bool escapes = true; 1003 ProgramStateRef state = C.getState(); 1004 1005 if (loc::MemRegionVal *regionLoc = dyn_cast<loc::MemRegionVal>(&loc)) { 1006 escapes = !regionLoc->getRegion()->hasStackStorage(); 1007 1008 if (!escapes) { 1009 // To test (3), generate a new state with the binding added. If it is 1010 // the same state, then it escapes (since the store cannot represent 1011 // the binding). 1012 escapes = (state == (state->bindLoc(*regionLoc, val))); 1013 } 1014 if (!escapes) { 1015 // Case 4: We do not currently model what happens when a symbol is 1016 // assigned to a struct field, so be conservative here and let the symbol 1017 // go. TODO: This could definitely be improved upon. 1018 escapes = !isa<VarRegion>(regionLoc->getRegion()); 1019 } 1020 } 1021 1022 // If our store can represent the binding and we aren't storing to something 1023 // that doesn't have local storage then just return and have the simulation 1024 // state continue as is. 1025 if (!escapes) 1026 return; 1027 1028 // Otherwise, find all symbols referenced by 'val' that we are tracking 1029 // and stop tracking them. 1030 state = state->scanReachableSymbols<StopTrackingCallback>(val).getState(); 1031 C.addTransition(state); 1032} 1033 1034// If a symbolic region is assumed to NULL (or another constant), stop tracking 1035// it - assuming that allocation failed on this path. 1036ProgramStateRef MallocChecker::evalAssume(ProgramStateRef state, 1037 SVal Cond, 1038 bool Assumption) const { 1039 RegionStateTy RS = state->get<RegionState>(); 1040 for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) { 1041 // If the symbol is assumed to NULL or another constant, this will 1042 // return an APSInt*. 1043 if (state->getSymVal(I.getKey())) 1044 state = state->remove<RegionState>(I.getKey()); 1045 } 1046 1047 // Realloc returns 0 when reallocation fails, which means that we should 1048 // restore the state of the pointer being reallocated. 1049 ReallocMap RP = state->get<ReallocPairs>(); 1050 for (ReallocMap::iterator I = RP.begin(), E = RP.end(); I != E; ++I) { 1051 // If the symbol is assumed to NULL or another constant, this will 1052 // return an APSInt*. 1053 if (state->getSymVal(I.getKey())) { 1054 SymbolRef ReallocSym = I.getData().ReallocatedSym; 1055 const RefState *RS = state->get<RegionState>(ReallocSym); 1056 if (RS) { 1057 if (RS->isReleased() && ! I.getData().IsFreeOnFailure) 1058 state = state->set<RegionState>(ReallocSym, 1059 RefState::getAllocateUnchecked(RS->getStmt())); 1060 } 1061 state = state->remove<ReallocPairs>(I.getKey()); 1062 } 1063 } 1064 1065 return state; 1066} 1067 1068// Check if the function is known to us. So, for example, we could 1069// conservatively assume it can free/reallocate it's pointer arguments. 1070// (We assume that the pointers cannot escape through calls to system 1071// functions not handled by this checker.) 1072bool MallocChecker::doesNotFreeMemory(const CallOrObjCMessage *Call, 1073 ProgramStateRef State) const { 1074 if (!Call) 1075 return false; 1076 1077 // For now, assume that any C++ call can free memory. 1078 // TODO: If we want to be more optimistic here, we'll need to make sure that 1079 // regions escape to C++ containers. They seem to do that even now, but for 1080 // mysterious reasons. 1081 if (Call->isCXXCall()) 1082 return false; 1083 1084 const Decl *D = Call->getDecl(); 1085 if (!D) 1086 return false; 1087 1088 ASTContext &ASTC = State->getStateManager().getContext(); 1089 1090 // If it's one of the allocation functions we can reason about, we model 1091 // its behavior explicitly. 1092 if (isa<FunctionDecl>(D) && isMemFunction(cast<FunctionDecl>(D), ASTC)) { 1093 return true; 1094 } 1095 1096 // If it's not a system call, assume it frees memory. 1097 SourceManager &SM = ASTC.getSourceManager(); 1098 if (!SM.isInSystemHeader(D->getLocation())) 1099 return false; 1100 1101 // Process C/ObjC functions. 1102 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { 1103 // White list the system functions whose arguments escape. 1104 const IdentifierInfo *II = FD->getIdentifier(); 1105 if (!II) 1106 return true; 1107 StringRef FName = II->getName(); 1108 1109 // White list thread local storage. 1110 if (FName.equals("pthread_setspecific")) 1111 return false; 1112 1113 // White list the 'XXXNoCopy' ObjC functions. 1114 if (FName.endswith("NoCopy")) { 1115 // Look for the deallocator argument. We know that the memory ownership 1116 // is not transfered only if the deallocator argument is 1117 // 'kCFAllocatorNull'. 1118 for (unsigned i = 1; i < Call->getNumArgs(); ++i) { 1119 const Expr *ArgE = Call->getArg(i)->IgnoreParenCasts(); 1120 if (const DeclRefExpr *DE = dyn_cast<DeclRefExpr>(ArgE)) { 1121 StringRef DeallocatorName = DE->getFoundDecl()->getName(); 1122 if (DeallocatorName == "kCFAllocatorNull") 1123 return true; 1124 } 1125 } 1126 return false; 1127 } 1128 1129 // PR12101 1130 // Many CoreFoundation and CoreGraphics might allow a tracked object 1131 // to escape. 1132 if (Call->isCFCGAllowingEscape(FName)) 1133 return false; 1134 1135 // Associating streams with malloced buffers. The pointer can escape if 1136 // 'closefn' is specified (and if that function does free memory). 1137 // Currently, we do not inspect the 'closefn' function (PR12101). 1138 if (FName == "funopen") 1139 if (Call->getNumArgs() >= 4 && !Call->getArgSVal(4).isConstant(0)) 1140 return false; 1141 1142 // Do not warn on pointers passed to 'setbuf' when used with std streams, 1143 // these leaks might be intentional when setting the buffer for stdio. 1144 // http://stackoverflow.com/questions/2671151/who-frees-setvbuf-buffer 1145 if (FName == "setbuf" || FName =="setbuffer" || 1146 FName == "setlinebuf" || FName == "setvbuf") { 1147 if (Call->getNumArgs() >= 1) 1148 if (const DeclRefExpr *Arg = 1149 dyn_cast<DeclRefExpr>(Call->getArg(0)->IgnoreParenCasts())) 1150 if (const VarDecl *D = dyn_cast<VarDecl>(Arg->getDecl())) 1151 if (D->getCanonicalDecl()->getName().find("std") 1152 != StringRef::npos) 1153 return false; 1154 } 1155 1156 // A bunch of other functions, which take ownership of a pointer (See retain 1157 // release checker). Not all the parameters here are invalidated, but the 1158 // Malloc checker cannot differentiate between them. The right way of doing 1159 // this would be to implement a pointer escapes callback. 1160 if (FName == "CVPixelBufferCreateWithBytes" || 1161 FName == "CGBitmapContextCreateWithData" || 1162 FName == "CVPixelBufferCreateWithPlanarBytes") { 1163 return false; 1164 } 1165 1166 // Otherwise, assume that the function does not free memory. 1167 // Most system calls, do not free the memory. 1168 return true; 1169 1170 // Process ObjC functions. 1171 } else if (const ObjCMethodDecl * ObjCD = dyn_cast<ObjCMethodDecl>(D)) { 1172 Selector S = ObjCD->getSelector(); 1173 1174 // White list the ObjC functions which do free memory. 1175 // - Anything containing 'freeWhenDone' param set to 1. 1176 // Ex: dataWithBytesNoCopy:length:freeWhenDone. 1177 for (unsigned i = 1; i < S.getNumArgs(); ++i) { 1178 if (S.getNameForSlot(i).equals("freeWhenDone")) { 1179 if (Call->getArgSVal(i).isConstant(1)) 1180 return false; 1181 else 1182 return true; 1183 } 1184 } 1185 1186 // If the first selector ends with NoCopy, assume that the ownership is 1187 // transfered as well. 1188 // Ex: [NSData dataWithBytesNoCopy:bytes length:10]; 1189 if (S.getNameForSlot(0).endswith("NoCopy")) { 1190 return false; 1191 } 1192 1193 // Otherwise, assume that the function does not free memory. 1194 // Most system calls, do not free the memory. 1195 return true; 1196 } 1197 1198 // Otherwise, assume that the function can free memory. 1199 return false; 1200 1201} 1202 1203// If the symbol we are tracking is invalidated, but not explicitly (ex: the &p 1204// escapes, when we are tracking p), do not track the symbol as we cannot reason 1205// about it anymore. 1206ProgramStateRef 1207MallocChecker::checkRegionChanges(ProgramStateRef State, 1208 const StoreManager::InvalidatedSymbols *invalidated, 1209 ArrayRef<const MemRegion *> ExplicitRegions, 1210 ArrayRef<const MemRegion *> Regions, 1211 const CallOrObjCMessage *Call) const { 1212 if (!invalidated || invalidated->empty()) 1213 return State; 1214 llvm::SmallPtrSet<SymbolRef, 8> WhitelistedSymbols; 1215 1216 // If it's a call which might free or reallocate memory, we assume that all 1217 // regions (explicit and implicit) escaped. 1218 1219 // Otherwise, whitelist explicit pointers; we still can track them. 1220 if (!Call || doesNotFreeMemory(Call, State)) { 1221 for (ArrayRef<const MemRegion *>::iterator I = ExplicitRegions.begin(), 1222 E = ExplicitRegions.end(); I != E; ++I) { 1223 if (const SymbolicRegion *R = (*I)->StripCasts()->getAs<SymbolicRegion>()) 1224 WhitelistedSymbols.insert(R->getSymbol()); 1225 } 1226 } 1227 1228 for (StoreManager::InvalidatedSymbols::const_iterator I=invalidated->begin(), 1229 E = invalidated->end(); I!=E; ++I) { 1230 SymbolRef sym = *I; 1231 if (WhitelistedSymbols.count(sym)) 1232 continue; 1233 // The symbol escaped. 1234 if (const RefState *RS = State->get<RegionState>(sym)) 1235 State = State->set<RegionState>(sym, RefState::getEscaped(RS->getStmt())); 1236 } 1237 return State; 1238} 1239 1240PathDiagnosticPiece * 1241MallocChecker::MallocBugVisitor::VisitNode(const ExplodedNode *N, 1242 const ExplodedNode *PrevN, 1243 BugReporterContext &BRC, 1244 BugReport &BR) { 1245 const RefState *RS = N->getState()->get<RegionState>(Sym); 1246 const RefState *RSPrev = PrevN->getState()->get<RegionState>(Sym); 1247 if (!RS && !RSPrev) 1248 return 0; 1249 1250 const Stmt *S = 0; 1251 const char *Msg = 0; 1252 1253 // Retrieve the associated statement. 1254 ProgramPoint ProgLoc = N->getLocation(); 1255 if (isa<StmtPoint>(ProgLoc)) 1256 S = cast<StmtPoint>(ProgLoc).getStmt(); 1257 // If an assumption was made on a branch, it should be caught 1258 // here by looking at the state transition. 1259 if (isa<BlockEdge>(ProgLoc)) { 1260 const CFGBlock *srcBlk = cast<BlockEdge>(ProgLoc).getSrc(); 1261 S = srcBlk->getTerminator(); 1262 } 1263 if (!S) 1264 return 0; 1265 1266 // Find out if this is an interesting point and what is the kind. 1267 if (Mode == Normal) { 1268 if (isAllocated(RS, RSPrev, S)) 1269 Msg = "Memory is allocated"; 1270 else if (isReleased(RS, RSPrev, S)) 1271 Msg = "Memory is released"; 1272 else if (isReallocFailedCheck(RS, RSPrev, S)) { 1273 Mode = ReallocationFailed; 1274 Msg = "Reallocation failed"; 1275 } 1276 1277 // We are in a special mode if a reallocation failed later in the path. 1278 } else if (Mode == ReallocationFailed) { 1279 // Generate a special diagnostic for the first realloc we find. 1280 if (!isAllocated(RS, RSPrev, S) && !isReleased(RS, RSPrev, S)) 1281 return 0; 1282 1283 // Check that the name of the function is realloc. 1284 const CallExpr *CE = dyn_cast<CallExpr>(S); 1285 if (!CE) 1286 return 0; 1287 const FunctionDecl *funDecl = CE->getDirectCallee(); 1288 if (!funDecl) 1289 return 0; 1290 StringRef FunName = funDecl->getName(); 1291 if (!(FunName.equals("realloc") || FunName.equals("reallocf"))) 1292 return 0; 1293 Msg = "Attempt to reallocate memory"; 1294 Mode = Normal; 1295 } 1296 1297 if (!Msg) 1298 return 0; 1299 1300 // Generate the extra diagnostic. 1301 PathDiagnosticLocation Pos(S, BRC.getSourceManager(), 1302 N->getLocationContext()); 1303 return new PathDiagnosticEventPiece(Pos, Msg); 1304} 1305 1306 1307#define REGISTER_CHECKER(name) \ 1308void ento::register##name(CheckerManager &mgr) {\ 1309 registerCStringCheckerBasic(mgr); \ 1310 mgr.registerChecker<MallocChecker>()->Filter.C##name = true;\ 1311} 1312 1313REGISTER_CHECKER(MallocPessimistic) 1314REGISTER_CHECKER(MallocOptimistic) 1315