| //=== MallocChecker.cpp - A malloc/free checker -------------------*- C++ -*--// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines malloc/free checker, which checks for potential memory |
| // leaks, double free, and use-after-free problems. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "ClangSACheckers.h" |
| #include "InterCheckerAPI.h" |
| #include "clang/StaticAnalyzer/Core/Checker.h" |
| #include "clang/StaticAnalyzer/Core/CheckerManager.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" |
| #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ObjCMessage.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h" |
| #include "clang/Basic/SourceManager.h" |
| #include "llvm/ADT/ImmutableMap.h" |
| #include "llvm/ADT/SmallString.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include <climits> |
| |
| using namespace clang; |
| using namespace ento; |
| |
| namespace { |
| |
| class RefState { |
| enum Kind { AllocateUnchecked, AllocateFailed, Released, Escaped, |
| Relinquished } K; |
| const Stmt *S; |
| |
| public: |
| RefState(Kind k, const Stmt *s) : K(k), S(s) {} |
| |
| bool isAllocated() const { return K == AllocateUnchecked; } |
| bool isReleased() const { return K == Released; } |
| |
| const Stmt *getStmt() const { return S; } |
| |
| bool operator==(const RefState &X) const { |
| return K == X.K && S == X.S; |
| } |
| |
| static RefState getAllocateUnchecked(const Stmt *s) { |
| return RefState(AllocateUnchecked, s); |
| } |
| static RefState getAllocateFailed() { |
| return RefState(AllocateFailed, 0); |
| } |
| static RefState getReleased(const Stmt *s) { return RefState(Released, s); } |
| static RefState getEscaped(const Stmt *s) { return RefState(Escaped, s); } |
| static RefState getRelinquished(const Stmt *s) { |
| return RefState(Relinquished, s); |
| } |
| |
| void Profile(llvm::FoldingSetNodeID &ID) const { |
| ID.AddInteger(K); |
| ID.AddPointer(S); |
| } |
| }; |
| |
| struct ReallocPair { |
| SymbolRef ReallocatedSym; |
| bool IsFreeOnFailure; |
| ReallocPair(SymbolRef S, bool F) : ReallocatedSym(S), IsFreeOnFailure(F) {} |
| void Profile(llvm::FoldingSetNodeID &ID) const { |
| ID.AddInteger(IsFreeOnFailure); |
| ID.AddPointer(ReallocatedSym); |
| } |
| bool operator==(const ReallocPair &X) const { |
| return ReallocatedSym == X.ReallocatedSym && |
| IsFreeOnFailure == X.IsFreeOnFailure; |
| } |
| }; |
| |
| typedef std::pair<const Stmt*, const MemRegion*> LeakInfo; |
| |
| class MallocChecker : public Checker<check::DeadSymbols, |
| check::EndPath, |
| check::PreStmt<ReturnStmt>, |
| check::PreStmt<CallExpr>, |
| check::PostStmt<CallExpr>, |
| check::PostStmt<BlockExpr>, |
| check::Location, |
| check::Bind, |
| eval::Assume, |
| check::RegionChanges> |
| { |
| mutable OwningPtr<BugType> BT_DoubleFree; |
| mutable OwningPtr<BugType> BT_Leak; |
| mutable OwningPtr<BugType> BT_UseFree; |
| mutable OwningPtr<BugType> BT_BadFree; |
| mutable IdentifierInfo *II_malloc, *II_free, *II_realloc, *II_calloc, |
| *II_valloc, *II_reallocf, *II_strndup, *II_strdup; |
| |
| public: |
| MallocChecker() : II_malloc(0), II_free(0), II_realloc(0), II_calloc(0), |
| II_valloc(0), II_reallocf(0), II_strndup(0), II_strdup(0) {} |
| |
| /// In pessimistic mode, the checker assumes that it does not know which |
| /// functions might free the memory. |
| struct ChecksFilter { |
| DefaultBool CMallocPessimistic; |
| DefaultBool CMallocOptimistic; |
| }; |
| |
| ChecksFilter Filter; |
| |
| void checkPreStmt(const CallExpr *S, CheckerContext &C) const; |
| void checkPostStmt(const CallExpr *CE, CheckerContext &C) const; |
| void checkPostStmt(const BlockExpr *BE, CheckerContext &C) const; |
| void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const; |
| void checkEndPath(CheckerContext &C) const; |
| void checkPreStmt(const ReturnStmt *S, CheckerContext &C) const; |
| ProgramStateRef evalAssume(ProgramStateRef state, SVal Cond, |
| bool Assumption) const; |
| void checkLocation(SVal l, bool isLoad, const Stmt *S, |
| CheckerContext &C) const; |
| void checkBind(SVal location, SVal val, const Stmt*S, |
| CheckerContext &C) const; |
| ProgramStateRef |
| checkRegionChanges(ProgramStateRef state, |
| const StoreManager::InvalidatedSymbols *invalidated, |
| ArrayRef<const MemRegion *> ExplicitRegions, |
| ArrayRef<const MemRegion *> Regions, |
| const CallOrObjCMessage *Call) const; |
| bool wantsRegionChangeUpdate(ProgramStateRef state) const { |
| return true; |
| } |
| |
| private: |
| void initIdentifierInfo(ASTContext &C) const; |
| |
| /// Check if this is one of the functions which can allocate/reallocate memory |
| /// pointed to by one of its arguments. |
| bool isMemFunction(const FunctionDecl *FD, ASTContext &C) const; |
| |
| static ProgramStateRef MallocMemReturnsAttr(CheckerContext &C, |
| const CallExpr *CE, |
| const OwnershipAttr* Att); |
| static ProgramStateRef MallocMemAux(CheckerContext &C, const CallExpr *CE, |
| const Expr *SizeEx, SVal Init, |
| ProgramStateRef state) { |
| return MallocMemAux(C, CE, |
| state->getSVal(SizeEx, C.getLocationContext()), |
| Init, state); |
| } |
| |
| static ProgramStateRef MallocMemAux(CheckerContext &C, const CallExpr *CE, |
| SVal SizeEx, SVal Init, |
| ProgramStateRef state); |
| |
| /// Update the RefState to reflect the new memory allocation. |
| static ProgramStateRef MallocUpdateRefState(CheckerContext &C, |
| const CallExpr *CE, |
| ProgramStateRef state); |
| |
| ProgramStateRef FreeMemAttr(CheckerContext &C, const CallExpr *CE, |
| const OwnershipAttr* Att) const; |
| ProgramStateRef FreeMemAux(CheckerContext &C, const CallExpr *CE, |
| ProgramStateRef state, unsigned Num, |
| bool Hold) const; |
| |
| ProgramStateRef ReallocMem(CheckerContext &C, const CallExpr *CE, |
| bool FreesMemOnFailure) const; |
| static ProgramStateRef CallocMem(CheckerContext &C, const CallExpr *CE); |
| |
| bool checkEscape(SymbolRef Sym, const Stmt *S, CheckerContext &C) const; |
| bool checkUseAfterFree(SymbolRef Sym, CheckerContext &C, |
| const Stmt *S = 0) const; |
| |
| /// Check if the function is not known to us. So, for example, we could |
| /// conservatively assume it can free/reallocate it's pointer arguments. |
| bool doesNotFreeMemory(const CallOrObjCMessage *Call, |
| ProgramStateRef State) const; |
| |
| static bool SummarizeValue(raw_ostream &os, SVal V); |
| static bool SummarizeRegion(raw_ostream &os, const MemRegion *MR); |
| void ReportBadFree(CheckerContext &C, SVal ArgVal, SourceRange range) const; |
| |
| /// Find the location of the allocation for Sym on the path leading to the |
| /// exploded node N. |
| LeakInfo getAllocationSite(const ExplodedNode *N, SymbolRef Sym, |
| CheckerContext &C) const; |
| |
| void reportLeak(SymbolRef Sym, ExplodedNode *N, CheckerContext &C) const; |
| |
| /// The bug visitor which allows us to print extra diagnostics along the |
| /// BugReport path. For example, showing the allocation site of the leaked |
| /// region. |
| class MallocBugVisitor : public BugReporterVisitorImpl<MallocBugVisitor> { |
| protected: |
| enum NotificationMode { |
| Normal, |
| ReallocationFailed |
| }; |
| |
| // The allocated region symbol tracked by the main analysis. |
| SymbolRef Sym; |
| |
| // The mode we are in, i.e. what kind of diagnostics will be emitted. |
| NotificationMode Mode; |
| |
| // A symbol from when the primary region should have been reallocated. |
| SymbolRef FailedReallocSymbol; |
| |
| public: |
| MallocBugVisitor(SymbolRef S) |
| : Sym(S), Mode(Normal), FailedReallocSymbol(0) {} |
| |
| virtual ~MallocBugVisitor() {} |
| |
| void Profile(llvm::FoldingSetNodeID &ID) const { |
| static int X = 0; |
| ID.AddPointer(&X); |
| ID.AddPointer(Sym); |
| } |
| |
| inline bool isAllocated(const RefState *S, const RefState *SPrev, |
| const Stmt *Stmt) { |
| // Did not track -> allocated. Other state (released) -> allocated. |
| return (Stmt && isa<CallExpr>(Stmt) && |
| (S && S->isAllocated()) && (!SPrev || !SPrev->isAllocated())); |
| } |
| |
| inline bool isReleased(const RefState *S, const RefState *SPrev, |
| const Stmt *Stmt) { |
| // Did not track -> released. Other state (allocated) -> released. |
| return (Stmt && isa<CallExpr>(Stmt) && |
| (S && S->isReleased()) && (!SPrev || !SPrev->isReleased())); |
| } |
| |
| inline bool isReallocFailedCheck(const RefState *S, const RefState *SPrev, |
| const Stmt *Stmt) { |
| // If the expression is not a call, and the state change is |
| // released -> allocated, it must be the realloc return value |
| // check. If we have to handle more cases here, it might be cleaner just |
| // to track this extra bit in the state itself. |
| return ((!Stmt || !isa<CallExpr>(Stmt)) && |
| (S && S->isAllocated()) && (SPrev && !SPrev->isAllocated())); |
| } |
| |
| PathDiagnosticPiece *VisitNode(const ExplodedNode *N, |
| const ExplodedNode *PrevN, |
| BugReporterContext &BRC, |
| BugReport &BR); |
| private: |
| class StackHintGeneratorForReallocationFailed |
| : public StackHintGeneratorForSymbol { |
| public: |
| StackHintGeneratorForReallocationFailed(SymbolRef S, StringRef M) |
| : StackHintGeneratorForSymbol(S, M) {} |
| |
| virtual std::string getMessageForArg(const Expr *ArgE, unsigned ArgIndex) { |
| SmallString<200> buf; |
| llvm::raw_svector_ostream os(buf); |
| |
| os << "Reallocation of "; |
| // Printed parameters start at 1, not 0. |
| printOrdinal(++ArgIndex, os); |
| os << " parameter failed"; |
| |
| return os.str(); |
| } |
| |
| virtual std::string getMessageForReturn(const CallExpr *CallExpr) { |
| return "Reallocation of returned value failed"; |
| } |
| }; |
| }; |
| }; |
| } // end anonymous namespace |
| |
| typedef llvm::ImmutableMap<SymbolRef, RefState> RegionStateTy; |
| typedef llvm::ImmutableMap<SymbolRef, ReallocPair > ReallocMap; |
| class RegionState {}; |
| class ReallocPairs {}; |
| namespace clang { |
| namespace ento { |
| template <> |
| struct ProgramStateTrait<RegionState> |
| : public ProgramStatePartialTrait<RegionStateTy> { |
| static void *GDMIndex() { static int x; return &x; } |
| }; |
| |
| template <> |
| struct ProgramStateTrait<ReallocPairs> |
| : public ProgramStatePartialTrait<ReallocMap> { |
| static void *GDMIndex() { static int x; return &x; } |
| }; |
| } |
| } |
| |
| namespace { |
| class StopTrackingCallback : public SymbolVisitor { |
| ProgramStateRef state; |
| public: |
| StopTrackingCallback(ProgramStateRef st) : state(st) {} |
| ProgramStateRef getState() const { return state; } |
| |
| bool VisitSymbol(SymbolRef sym) { |
| state = state->remove<RegionState>(sym); |
| return true; |
| } |
| }; |
| } // end anonymous namespace |
| |
| void MallocChecker::initIdentifierInfo(ASTContext &Ctx) const { |
| if (!II_malloc) |
| II_malloc = &Ctx.Idents.get("malloc"); |
| if (!II_free) |
| II_free = &Ctx.Idents.get("free"); |
| if (!II_realloc) |
| II_realloc = &Ctx.Idents.get("realloc"); |
| if (!II_reallocf) |
| II_reallocf = &Ctx.Idents.get("reallocf"); |
| if (!II_calloc) |
| II_calloc = &Ctx.Idents.get("calloc"); |
| if (!II_valloc) |
| II_valloc = &Ctx.Idents.get("valloc"); |
| if (!II_strdup) |
| II_strdup = &Ctx.Idents.get("strdup"); |
| if (!II_strndup) |
| II_strndup = &Ctx.Idents.get("strndup"); |
| } |
| |
| bool MallocChecker::isMemFunction(const FunctionDecl *FD, ASTContext &C) const { |
| if (!FD) |
| return false; |
| IdentifierInfo *FunI = FD->getIdentifier(); |
| if (!FunI) |
| return false; |
| |
| initIdentifierInfo(C); |
| |
| if (FunI == II_malloc || FunI == II_free || FunI == II_realloc || |
| FunI == II_reallocf || FunI == II_calloc || FunI == II_valloc || |
| FunI == II_strdup || FunI == II_strndup) |
| return true; |
| |
| if (Filter.CMallocOptimistic && FD->hasAttrs() && |
| FD->specific_attr_begin<OwnershipAttr>() != |
| FD->specific_attr_end<OwnershipAttr>()) |
| return true; |
| |
| |
| return false; |
| } |
| |
| void MallocChecker::checkPostStmt(const CallExpr *CE, CheckerContext &C) const { |
| const FunctionDecl *FD = C.getCalleeDecl(CE); |
| if (!FD) |
| return; |
| |
| initIdentifierInfo(C.getASTContext()); |
| IdentifierInfo *FunI = FD->getIdentifier(); |
| if (!FunI) |
| return; |
| |
| ProgramStateRef State = C.getState(); |
| if (FunI == II_malloc || FunI == II_valloc) { |
| if (CE->getNumArgs() < 1) |
| return; |
| State = MallocMemAux(C, CE, CE->getArg(0), UndefinedVal(), State); |
| } else if (FunI == II_realloc) { |
| State = ReallocMem(C, CE, false); |
| } else if (FunI == II_reallocf) { |
| State = ReallocMem(C, CE, true); |
| } else if (FunI == II_calloc) { |
| State = CallocMem(C, CE); |
| } else if (FunI == II_free) { |
| State = FreeMemAux(C, CE, C.getState(), 0, false); |
| } else if (FunI == II_strdup) { |
| State = MallocUpdateRefState(C, CE, State); |
| } else if (FunI == II_strndup) { |
| State = MallocUpdateRefState(C, CE, State); |
| } else if (Filter.CMallocOptimistic) { |
| // Check all the attributes, if there are any. |
| // There can be multiple of these attributes. |
| if (FD->hasAttrs()) |
| for (specific_attr_iterator<OwnershipAttr> |
| i = FD->specific_attr_begin<OwnershipAttr>(), |
| e = FD->specific_attr_end<OwnershipAttr>(); |
| i != e; ++i) { |
| switch ((*i)->getOwnKind()) { |
| case OwnershipAttr::Returns: |
| State = MallocMemReturnsAttr(C, CE, *i); |
| break; |
| case OwnershipAttr::Takes: |
| case OwnershipAttr::Holds: |
| State = FreeMemAttr(C, CE, *i); |
| break; |
| } |
| } |
| } |
| C.addTransition(State); |
| } |
| |
| ProgramStateRef MallocChecker::MallocMemReturnsAttr(CheckerContext &C, |
| const CallExpr *CE, |
| const OwnershipAttr* Att) { |
| if (Att->getModule() != "malloc") |
| return 0; |
| |
| OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end(); |
| if (I != E) { |
| return MallocMemAux(C, CE, CE->getArg(*I), UndefinedVal(), C.getState()); |
| } |
| return MallocMemAux(C, CE, UnknownVal(), UndefinedVal(), C.getState()); |
| } |
| |
| ProgramStateRef MallocChecker::MallocMemAux(CheckerContext &C, |
| const CallExpr *CE, |
| SVal Size, SVal Init, |
| ProgramStateRef state) { |
| // Get the return value. |
| SVal retVal = state->getSVal(CE, C.getLocationContext()); |
| |
| // We expect the malloc functions to return a pointer. |
| if (!isa<Loc>(retVal)) |
| return 0; |
| |
| // Fill the region with the initialization value. |
| state = state->bindDefault(retVal, Init); |
| |
| // Set the region's extent equal to the Size parameter. |
| const SymbolicRegion *R = |
| dyn_cast_or_null<SymbolicRegion>(retVal.getAsRegion()); |
| if (!R) |
| return 0; |
| if (isa<DefinedOrUnknownSVal>(Size)) { |
| SValBuilder &svalBuilder = C.getSValBuilder(); |
| DefinedOrUnknownSVal Extent = R->getExtent(svalBuilder); |
| DefinedOrUnknownSVal DefinedSize = cast<DefinedOrUnknownSVal>(Size); |
| DefinedOrUnknownSVal extentMatchesSize = |
| svalBuilder.evalEQ(state, Extent, DefinedSize); |
| |
| state = state->assume(extentMatchesSize, true); |
| assert(state); |
| } |
| |
| return MallocUpdateRefState(C, CE, state); |
| } |
| |
| ProgramStateRef MallocChecker::MallocUpdateRefState(CheckerContext &C, |
| const CallExpr *CE, |
| ProgramStateRef state) { |
| // Get the return value. |
| SVal retVal = state->getSVal(CE, C.getLocationContext()); |
| |
| // We expect the malloc functions to return a pointer. |
| if (!isa<Loc>(retVal)) |
| return 0; |
| |
| SymbolRef Sym = retVal.getAsLocSymbol(); |
| assert(Sym); |
| |
| // Set the symbol's state to Allocated. |
| return state->set<RegionState>(Sym, RefState::getAllocateUnchecked(CE)); |
| |
| } |
| |
| ProgramStateRef MallocChecker::FreeMemAttr(CheckerContext &C, |
| const CallExpr *CE, |
| const OwnershipAttr* Att) const { |
| if (Att->getModule() != "malloc") |
| return 0; |
| |
| ProgramStateRef State = C.getState(); |
| |
| for (OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end(); |
| I != E; ++I) { |
| ProgramStateRef StateI = FreeMemAux(C, CE, State, *I, |
| Att->getOwnKind() == OwnershipAttr::Holds); |
| if (StateI) |
| State = StateI; |
| } |
| return State; |
| } |
| |
| ProgramStateRef MallocChecker::FreeMemAux(CheckerContext &C, |
| const CallExpr *CE, |
| ProgramStateRef state, |
| unsigned Num, |
| bool Hold) const { |
| if (CE->getNumArgs() < (Num + 1)) |
| return 0; |
| |
| const Expr *ArgExpr = CE->getArg(Num); |
| SVal ArgVal = state->getSVal(ArgExpr, C.getLocationContext()); |
| if (!isa<DefinedOrUnknownSVal>(ArgVal)) |
| return 0; |
| DefinedOrUnknownSVal location = cast<DefinedOrUnknownSVal>(ArgVal); |
| |
| // Check for null dereferences. |
| if (!isa<Loc>(location)) |
| return 0; |
| |
| // The explicit NULL case, no operation is performed. |
| ProgramStateRef notNullState, nullState; |
| llvm::tie(notNullState, nullState) = state->assume(location); |
| if (nullState && !notNullState) |
| return 0; |
| |
| // Unknown values could easily be okay |
| // Undefined values are handled elsewhere |
| if (ArgVal.isUnknownOrUndef()) |
| return 0; |
| |
| const MemRegion *R = ArgVal.getAsRegion(); |
| |
| // Nonlocs can't be freed, of course. |
| // Non-region locations (labels and fixed addresses) also shouldn't be freed. |
| if (!R) { |
| ReportBadFree(C, ArgVal, ArgExpr->getSourceRange()); |
| return 0; |
| } |
| |
| R = R->StripCasts(); |
| |
| // Blocks might show up as heap data, but should not be free()d |
| if (isa<BlockDataRegion>(R)) { |
| ReportBadFree(C, ArgVal, ArgExpr->getSourceRange()); |
| return 0; |
| } |
| |
| const MemSpaceRegion *MS = R->getMemorySpace(); |
| |
| // Parameters, locals, statics, and globals shouldn't be freed. |
| if (!(isa<UnknownSpaceRegion>(MS) || isa<HeapSpaceRegion>(MS))) { |
| // FIXME: at the time this code was written, malloc() regions were |
| // represented by conjured symbols, which are all in UnknownSpaceRegion. |
| // This means that there isn't actually anything from HeapSpaceRegion |
| // that should be freed, even though we allow it here. |
| // Of course, free() can work on memory allocated outside the current |
| // function, so UnknownSpaceRegion is always a possibility. |
| // False negatives are better than false positives. |
| |
| ReportBadFree(C, ArgVal, ArgExpr->getSourceRange()); |
| return 0; |
| } |
| |
| const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R); |
| // Various cases could lead to non-symbol values here. |
| // For now, ignore them. |
| if (!SR) |
| return 0; |
| |
| SymbolRef Sym = SR->getSymbol(); |
| const RefState *RS = state->get<RegionState>(Sym); |
| |
| // If the symbol has not been tracked, return. This is possible when free() is |
| // called on a pointer that does not get its pointee directly from malloc(). |
| // Full support of this requires inter-procedural analysis. |
| if (!RS) |
| return 0; |
| |
| // Check double free. |
| if (RS->isReleased()) { |
| if (ExplodedNode *N = C.generateSink()) { |
| if (!BT_DoubleFree) |
| BT_DoubleFree.reset( |
| new BugType("Double free", "Memory Error")); |
| BugReport *R = new BugReport(*BT_DoubleFree, |
| "Attempt to free released memory", N); |
| R->addRange(ArgExpr->getSourceRange()); |
| R->markInteresting(Sym); |
| R->addVisitor(new MallocBugVisitor(Sym)); |
| C.EmitReport(R); |
| } |
| return 0; |
| } |
| |
| // Normal free. |
| if (Hold) |
| return state->set<RegionState>(Sym, RefState::getRelinquished(CE)); |
| return state->set<RegionState>(Sym, RefState::getReleased(CE)); |
| } |
| |
| bool MallocChecker::SummarizeValue(raw_ostream &os, SVal V) { |
| if (nonloc::ConcreteInt *IntVal = dyn_cast<nonloc::ConcreteInt>(&V)) |
| os << "an integer (" << IntVal->getValue() << ")"; |
| else if (loc::ConcreteInt *ConstAddr = dyn_cast<loc::ConcreteInt>(&V)) |
| os << "a constant address (" << ConstAddr->getValue() << ")"; |
| else if (loc::GotoLabel *Label = dyn_cast<loc::GotoLabel>(&V)) |
| os << "the address of the label '" << Label->getLabel()->getName() << "'"; |
| else |
| return false; |
| |
| return true; |
| } |
| |
| bool MallocChecker::SummarizeRegion(raw_ostream &os, |
| const MemRegion *MR) { |
| switch (MR->getKind()) { |
| case MemRegion::FunctionTextRegionKind: { |
| const FunctionDecl *FD = cast<FunctionTextRegion>(MR)->getDecl(); |
| if (FD) |
| os << "the address of the function '" << *FD << '\''; |
| else |
| os << "the address of a function"; |
| return true; |
| } |
| case MemRegion::BlockTextRegionKind: |
| os << "block text"; |
| return true; |
| case MemRegion::BlockDataRegionKind: |
| // FIXME: where the block came from? |
| os << "a block"; |
| return true; |
| default: { |
| const MemSpaceRegion *MS = MR->getMemorySpace(); |
| |
| if (isa<StackLocalsSpaceRegion>(MS)) { |
| const VarRegion *VR = dyn_cast<VarRegion>(MR); |
| const VarDecl *VD; |
| if (VR) |
| VD = VR->getDecl(); |
| else |
| VD = NULL; |
| |
| if (VD) |
| os << "the address of the local variable '" << VD->getName() << "'"; |
| else |
| os << "the address of a local stack variable"; |
| return true; |
| } |
| |
| if (isa<StackArgumentsSpaceRegion>(MS)) { |
| const VarRegion *VR = dyn_cast<VarRegion>(MR); |
| const VarDecl *VD; |
| if (VR) |
| VD = VR->getDecl(); |
| else |
| VD = NULL; |
| |
| if (VD) |
| os << "the address of the parameter '" << VD->getName() << "'"; |
| else |
| os << "the address of a parameter"; |
| return true; |
| } |
| |
| if (isa<GlobalsSpaceRegion>(MS)) { |
| const VarRegion *VR = dyn_cast<VarRegion>(MR); |
| const VarDecl *VD; |
| if (VR) |
| VD = VR->getDecl(); |
| else |
| VD = NULL; |
| |
| if (VD) { |
| if (VD->isStaticLocal()) |
| os << "the address of the static variable '" << VD->getName() << "'"; |
| else |
| os << "the address of the global variable '" << VD->getName() << "'"; |
| } else |
| os << "the address of a global variable"; |
| return true; |
| } |
| |
| return false; |
| } |
| } |
| } |
| |
| void MallocChecker::ReportBadFree(CheckerContext &C, SVal ArgVal, |
| SourceRange range) const { |
| if (ExplodedNode *N = C.generateSink()) { |
| if (!BT_BadFree) |
| BT_BadFree.reset(new BugType("Bad free", "Memory Error")); |
| |
| SmallString<100> buf; |
| llvm::raw_svector_ostream os(buf); |
| |
| const MemRegion *MR = ArgVal.getAsRegion(); |
| if (MR) { |
| while (const ElementRegion *ER = dyn_cast<ElementRegion>(MR)) |
| MR = ER->getSuperRegion(); |
| |
| // Special case for alloca() |
| if (isa<AllocaRegion>(MR)) |
| os << "Argument to free() was allocated by alloca(), not malloc()"; |
| else { |
| os << "Argument to free() is "; |
| if (SummarizeRegion(os, MR)) |
| os << ", which is not memory allocated by malloc()"; |
| else |
| os << "not memory allocated by malloc()"; |
| } |
| } else { |
| os << "Argument to free() is "; |
| if (SummarizeValue(os, ArgVal)) |
| os << ", which is not memory allocated by malloc()"; |
| else |
| os << "not memory allocated by malloc()"; |
| } |
| |
| BugReport *R = new BugReport(*BT_BadFree, os.str(), N); |
| R->markInteresting(MR); |
| R->addRange(range); |
| C.EmitReport(R); |
| } |
| } |
| |
| ProgramStateRef MallocChecker::ReallocMem(CheckerContext &C, |
| const CallExpr *CE, |
| bool FreesOnFail) const { |
| if (CE->getNumArgs() < 2) |
| return 0; |
| |
| ProgramStateRef state = C.getState(); |
| const Expr *arg0Expr = CE->getArg(0); |
| const LocationContext *LCtx = C.getLocationContext(); |
| SVal Arg0Val = state->getSVal(arg0Expr, LCtx); |
| if (!isa<DefinedOrUnknownSVal>(Arg0Val)) |
| return 0; |
| DefinedOrUnknownSVal arg0Val = cast<DefinedOrUnknownSVal>(Arg0Val); |
| |
| SValBuilder &svalBuilder = C.getSValBuilder(); |
| |
| DefinedOrUnknownSVal PtrEQ = |
| svalBuilder.evalEQ(state, arg0Val, svalBuilder.makeNull()); |
| |
| // Get the size argument. If there is no size arg then give up. |
| const Expr *Arg1 = CE->getArg(1); |
| if (!Arg1) |
| return 0; |
| |
| // Get the value of the size argument. |
| SVal Arg1ValG = state->getSVal(Arg1, LCtx); |
| if (!isa<DefinedOrUnknownSVal>(Arg1ValG)) |
| return 0; |
| DefinedOrUnknownSVal Arg1Val = cast<DefinedOrUnknownSVal>(Arg1ValG); |
| |
| // Compare the size argument to 0. |
| DefinedOrUnknownSVal SizeZero = |
| svalBuilder.evalEQ(state, Arg1Val, |
| svalBuilder.makeIntValWithPtrWidth(0, false)); |
| |
| ProgramStateRef StatePtrIsNull, StatePtrNotNull; |
| llvm::tie(StatePtrIsNull, StatePtrNotNull) = state->assume(PtrEQ); |
| ProgramStateRef StateSizeIsZero, StateSizeNotZero; |
| llvm::tie(StateSizeIsZero, StateSizeNotZero) = state->assume(SizeZero); |
| // We only assume exceptional states if they are definitely true; if the |
| // state is under-constrained, assume regular realloc behavior. |
| bool PrtIsNull = StatePtrIsNull && !StatePtrNotNull; |
| bool SizeIsZero = StateSizeIsZero && !StateSizeNotZero; |
| |
| // If the ptr is NULL and the size is not 0, the call is equivalent to |
| // malloc(size). |
| if ( PrtIsNull && !SizeIsZero) { |
| ProgramStateRef stateMalloc = MallocMemAux(C, CE, CE->getArg(1), |
| UndefinedVal(), StatePtrIsNull); |
| return stateMalloc; |
| } |
| |
| if (PrtIsNull && SizeIsZero) |
| return 0; |
| |
| // Get the from and to pointer symbols as in toPtr = realloc(fromPtr, size). |
| assert(!PrtIsNull); |
| SymbolRef FromPtr = arg0Val.getAsSymbol(); |
| SVal RetVal = state->getSVal(CE, LCtx); |
| SymbolRef ToPtr = RetVal.getAsSymbol(); |
| if (!FromPtr || !ToPtr) |
| return 0; |
| |
| // If the size is 0, free the memory. |
| if (SizeIsZero) |
| if (ProgramStateRef stateFree = FreeMemAux(C, CE, StateSizeIsZero,0,false)){ |
| // The semantics of the return value are: |
| // If size was equal to 0, either NULL or a pointer suitable to be passed |
| // to free() is returned. |
| stateFree = stateFree->set<ReallocPairs>(ToPtr, |
| ReallocPair(FromPtr, FreesOnFail)); |
| C.getSymbolManager().addSymbolDependency(ToPtr, FromPtr); |
| return stateFree; |
| } |
| |
| // Default behavior. |
| if (ProgramStateRef stateFree = FreeMemAux(C, CE, state, 0, false)) { |
| // FIXME: We should copy the content of the original buffer. |
| ProgramStateRef stateRealloc = MallocMemAux(C, CE, CE->getArg(1), |
| UnknownVal(), stateFree); |
| if (!stateRealloc) |
| return 0; |
| stateRealloc = stateRealloc->set<ReallocPairs>(ToPtr, |
| ReallocPair(FromPtr, FreesOnFail)); |
| C.getSymbolManager().addSymbolDependency(ToPtr, FromPtr); |
| return stateRealloc; |
| } |
| return 0; |
| } |
| |
| ProgramStateRef MallocChecker::CallocMem(CheckerContext &C, const CallExpr *CE){ |
| if (CE->getNumArgs() < 2) |
| return 0; |
| |
| ProgramStateRef state = C.getState(); |
| SValBuilder &svalBuilder = C.getSValBuilder(); |
| const LocationContext *LCtx = C.getLocationContext(); |
| SVal count = state->getSVal(CE->getArg(0), LCtx); |
| SVal elementSize = state->getSVal(CE->getArg(1), LCtx); |
| SVal TotalSize = svalBuilder.evalBinOp(state, BO_Mul, count, elementSize, |
| svalBuilder.getContext().getSizeType()); |
| SVal zeroVal = svalBuilder.makeZeroVal(svalBuilder.getContext().CharTy); |
| |
| return MallocMemAux(C, CE, TotalSize, zeroVal, state); |
| } |
| |
| LeakInfo |
| MallocChecker::getAllocationSite(const ExplodedNode *N, SymbolRef Sym, |
| CheckerContext &C) const { |
| const LocationContext *LeakContext = N->getLocationContext(); |
| // Walk the ExplodedGraph backwards and find the first node that referred to |
| // the tracked symbol. |
| const ExplodedNode *AllocNode = N; |
| const MemRegion *ReferenceRegion = 0; |
| |
| while (N) { |
| ProgramStateRef State = N->getState(); |
| if (!State->get<RegionState>(Sym)) |
| break; |
| |
| // Find the most recent expression bound to the symbol in the current |
| // context. |
| if (!ReferenceRegion) { |
| if (const MemRegion *MR = C.getLocationRegionIfPostStore(N)) { |
| SVal Val = State->getSVal(MR); |
| if (Val.getAsLocSymbol() == Sym) |
| ReferenceRegion = MR; |
| } |
| } |
| |
| // Allocation node, is the last node in the current context in which the |
| // symbol was tracked. |
| if (N->getLocationContext() == LeakContext) |
| AllocNode = N; |
| N = N->pred_empty() ? NULL : *(N->pred_begin()); |
| } |
| |
| ProgramPoint P = AllocNode->getLocation(); |
| const Stmt *AllocationStmt = 0; |
| if (isa<StmtPoint>(P)) |
| AllocationStmt = cast<StmtPoint>(P).getStmt(); |
| |
| return LeakInfo(AllocationStmt, ReferenceRegion); |
| } |
| |
| void MallocChecker::reportLeak(SymbolRef Sym, ExplodedNode *N, |
| CheckerContext &C) const { |
| assert(N); |
| if (!BT_Leak) { |
| BT_Leak.reset(new BugType("Memory leak", "Memory Error")); |
| // Leaks should not be reported if they are post-dominated by a sink: |
| // (1) Sinks are higher importance bugs. |
| // (2) NoReturnFunctionChecker uses sink nodes to represent paths ending |
| // with __noreturn functions such as assert() or exit(). We choose not |
| // to report leaks on such paths. |
| BT_Leak->setSuppressOnSink(true); |
| } |
| |
| // Most bug reports are cached at the location where they occurred. |
| // With leaks, we want to unique them by the location where they were |
| // allocated, and only report a single path. |
| PathDiagnosticLocation LocUsedForUniqueing; |
| const Stmt *AllocStmt = 0; |
| const MemRegion *Region = 0; |
| llvm::tie(AllocStmt, Region) = getAllocationSite(N, Sym, C); |
| if (AllocStmt) |
| LocUsedForUniqueing = PathDiagnosticLocation::createBegin(AllocStmt, |
| C.getSourceManager(), N->getLocationContext()); |
| |
| SmallString<200> buf; |
| llvm::raw_svector_ostream os(buf); |
| os << "Memory is never released; potential leak"; |
| if (Region) { |
| os << " of memory pointed to by '"; |
| Region->dumpPretty(os); |
| os <<'\''; |
| } |
| |
| BugReport *R = new BugReport(*BT_Leak, os.str(), N, LocUsedForUniqueing); |
| R->markInteresting(Sym); |
| R->addVisitor(new MallocBugVisitor(Sym)); |
| C.EmitReport(R); |
| } |
| |
| void MallocChecker::checkDeadSymbols(SymbolReaper &SymReaper, |
| CheckerContext &C) const |
| { |
| if (!SymReaper.hasDeadSymbols()) |
| return; |
| |
| ProgramStateRef state = C.getState(); |
| RegionStateTy RS = state->get<RegionState>(); |
| RegionStateTy::Factory &F = state->get_context<RegionState>(); |
| |
| bool generateReport = false; |
| llvm::SmallVector<SymbolRef, 2> Errors; |
| for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) { |
| if (SymReaper.isDead(I->first)) { |
| if (I->second.isAllocated()) { |
| generateReport = true; |
| Errors.push_back(I->first); |
| } |
| // Remove the dead symbol from the map. |
| RS = F.remove(RS, I->first); |
| |
| } |
| } |
| |
| // Cleanup the Realloc Pairs Map. |
| ReallocMap RP = state->get<ReallocPairs>(); |
| for (ReallocMap::iterator I = RP.begin(), E = RP.end(); I != E; ++I) { |
| if (SymReaper.isDead(I->first) || |
| SymReaper.isDead(I->second.ReallocatedSym)) { |
| state = state->remove<ReallocPairs>(I->first); |
| } |
| } |
| |
| // Generate leak node. |
| static SimpleProgramPointTag Tag("MallocChecker : DeadSymbolsLeak"); |
| ExplodedNode *N = C.addTransition(C.getState(), C.getPredecessor(), &Tag); |
| |
| if (generateReport) { |
| for (llvm::SmallVector<SymbolRef, 2>::iterator |
| I = Errors.begin(), E = Errors.end(); I != E; ++I) { |
| reportLeak(*I, N, C); |
| } |
| } |
| C.addTransition(state->set<RegionState>(RS), N); |
| } |
| |
| void MallocChecker::checkEndPath(CheckerContext &C) const { |
| ProgramStateRef state = C.getState(); |
| RegionStateTy M = state->get<RegionState>(); |
| |
| // If inside inlined call, skip it. |
| if (C.getLocationContext()->getParent() != 0) |
| return; |
| |
| for (RegionStateTy::iterator I = M.begin(), E = M.end(); I != E; ++I) { |
| RefState RS = I->second; |
| if (RS.isAllocated()) { |
| ExplodedNode *N = C.addTransition(state); |
| if (N) |
| reportLeak(I->first, N, C); |
| } |
| } |
| } |
| |
| bool MallocChecker::checkEscape(SymbolRef Sym, const Stmt *S, |
| CheckerContext &C) const { |
| ProgramStateRef state = C.getState(); |
| const RefState *RS = state->get<RegionState>(Sym); |
| if (!RS) |
| return false; |
| |
| if (RS->isAllocated()) { |
| state = state->set<RegionState>(Sym, RefState::getEscaped(S)); |
| C.addTransition(state); |
| return true; |
| } |
| return false; |
| } |
| |
| void MallocChecker::checkPreStmt(const CallExpr *CE, CheckerContext &C) const { |
| if (isMemFunction(C.getCalleeDecl(CE), C.getASTContext())) |
| return; |
| |
| // Check use after free, when a freed pointer is passed to a call. |
| ProgramStateRef State = C.getState(); |
| for (CallExpr::const_arg_iterator I = CE->arg_begin(), |
| E = CE->arg_end(); I != E; ++I) { |
| const Expr *A = *I; |
| if (A->getType().getTypePtr()->isAnyPointerType()) { |
| SymbolRef Sym = State->getSVal(A, C.getLocationContext()).getAsSymbol(); |
| if (!Sym) |
| continue; |
| if (checkUseAfterFree(Sym, C, A)) |
| return; |
| } |
| } |
| } |
| |
| void MallocChecker::checkPreStmt(const ReturnStmt *S, CheckerContext &C) const { |
| const Expr *E = S->getRetValue(); |
| if (!E) |
| return; |
| |
| // Check if we are returning a symbol. |
| SVal RetVal = C.getState()->getSVal(E, C.getLocationContext()); |
| SymbolRef Sym = RetVal.getAsSymbol(); |
| if (!Sym) |
| // If we are returning a field of the allocated struct or an array element, |
| // the callee could still free the memory. |
| // TODO: This logic should be a part of generic symbol escape callback. |
| if (const MemRegion *MR = RetVal.getAsRegion()) |
| if (isa<FieldRegion>(MR) || isa<ElementRegion>(MR)) |
| if (const SymbolicRegion *BMR = |
| dyn_cast<SymbolicRegion>(MR->getBaseRegion())) |
| Sym = BMR->getSymbol(); |
| if (!Sym) |
| return; |
| |
| // Check if we are returning freed memory. |
| if (checkUseAfterFree(Sym, C, E)) |
| return; |
| |
| // If this function body is not inlined, check if the symbol is escaping. |
| if (C.getLocationContext()->getParent() == 0) |
| checkEscape(Sym, E, C); |
| } |
| |
| // TODO: Blocks should be either inlined or should call invalidate regions |
| // upon invocation. After that's in place, special casing here will not be |
| // needed. |
| void MallocChecker::checkPostStmt(const BlockExpr *BE, |
| CheckerContext &C) const { |
| |
| // Scan the BlockDecRefExprs for any object the retain count checker |
| // may be tracking. |
| if (!BE->getBlockDecl()->hasCaptures()) |
| return; |
| |
| ProgramStateRef state = C.getState(); |
| const BlockDataRegion *R = |
| cast<BlockDataRegion>(state->getSVal(BE, |
| C.getLocationContext()).getAsRegion()); |
| |
| BlockDataRegion::referenced_vars_iterator I = R->referenced_vars_begin(), |
| E = R->referenced_vars_end(); |
| |
| if (I == E) |
| return; |
| |
| SmallVector<const MemRegion*, 10> Regions; |
| const LocationContext *LC = C.getLocationContext(); |
| MemRegionManager &MemMgr = C.getSValBuilder().getRegionManager(); |
| |
| for ( ; I != E; ++I) { |
| const VarRegion *VR = *I; |
| if (VR->getSuperRegion() == R) { |
| VR = MemMgr.getVarRegion(VR->getDecl(), LC); |
| } |
| Regions.push_back(VR); |
| } |
| |
| state = |
| state->scanReachableSymbols<StopTrackingCallback>(Regions.data(), |
| Regions.data() + Regions.size()).getState(); |
| C.addTransition(state); |
| } |
| |
| bool MallocChecker::checkUseAfterFree(SymbolRef Sym, CheckerContext &C, |
| const Stmt *S) const { |
| assert(Sym); |
| const RefState *RS = C.getState()->get<RegionState>(Sym); |
| if (RS && RS->isReleased()) { |
| if (ExplodedNode *N = C.generateSink()) { |
| if (!BT_UseFree) |
| BT_UseFree.reset(new BugType("Use-after-free", "Memory Error")); |
| |
| BugReport *R = new BugReport(*BT_UseFree, |
| "Use of memory after it is freed",N); |
| if (S) |
| R->addRange(S->getSourceRange()); |
| R->markInteresting(Sym); |
| R->addVisitor(new MallocBugVisitor(Sym)); |
| C.EmitReport(R); |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| // Check if the location is a freed symbolic region. |
| void MallocChecker::checkLocation(SVal l, bool isLoad, const Stmt *S, |
| CheckerContext &C) const { |
| SymbolRef Sym = l.getLocSymbolInBase(); |
| if (Sym) |
| checkUseAfterFree(Sym, C); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Check various ways a symbol can be invalidated. |
| // TODO: This logic (the next 3 functions) is copied/similar to the |
| // RetainRelease checker. We might want to factor this out. |
| //===----------------------------------------------------------------------===// |
| |
| // Stop tracking symbols when a value escapes as a result of checkBind. |
| // A value escapes in three possible cases: |
| // (1) we are binding to something that is not a memory region. |
| // (2) we are binding to a memregion that does not have stack storage |
| // (3) we are binding to a memregion with stack storage that the store |
| // does not understand. |
| void MallocChecker::checkBind(SVal loc, SVal val, const Stmt *S, |
| CheckerContext &C) const { |
| // Are we storing to something that causes the value to "escape"? |
| bool escapes = true; |
| ProgramStateRef state = C.getState(); |
| |
| if (loc::MemRegionVal *regionLoc = dyn_cast<loc::MemRegionVal>(&loc)) { |
| escapes = !regionLoc->getRegion()->hasStackStorage(); |
| |
| if (!escapes) { |
| // To test (3), generate a new state with the binding added. If it is |
| // the same state, then it escapes (since the store cannot represent |
| // the binding). |
| escapes = (state == (state->bindLoc(*regionLoc, val))); |
| } |
| if (!escapes) { |
| // Case 4: We do not currently model what happens when a symbol is |
| // assigned to a struct field, so be conservative here and let the symbol |
| // go. TODO: This could definitely be improved upon. |
| escapes = !isa<VarRegion>(regionLoc->getRegion()); |
| } |
| } |
| |
| // If our store can represent the binding and we aren't storing to something |
| // that doesn't have local storage then just return and have the simulation |
| // state continue as is. |
| if (!escapes) |
| return; |
| |
| // Otherwise, find all symbols referenced by 'val' that we are tracking |
| // and stop tracking them. |
| state = state->scanReachableSymbols<StopTrackingCallback>(val).getState(); |
| C.addTransition(state); |
| } |
| |
| // If a symbolic region is assumed to NULL (or another constant), stop tracking |
| // it - assuming that allocation failed on this path. |
| ProgramStateRef MallocChecker::evalAssume(ProgramStateRef state, |
| SVal Cond, |
| bool Assumption) const { |
| RegionStateTy RS = state->get<RegionState>(); |
| for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) { |
| // If the symbol is assumed to NULL or another constant, this will |
| // return an APSInt*. |
| if (state->getSymVal(I.getKey())) |
| state = state->remove<RegionState>(I.getKey()); |
| } |
| |
| // Realloc returns 0 when reallocation fails, which means that we should |
| // restore the state of the pointer being reallocated. |
| ReallocMap RP = state->get<ReallocPairs>(); |
| for (ReallocMap::iterator I = RP.begin(), E = RP.end(); I != E; ++I) { |
| // If the symbol is assumed to NULL or another constant, this will |
| // return an APSInt*. |
| if (state->getSymVal(I.getKey())) { |
| SymbolRef ReallocSym = I.getData().ReallocatedSym; |
| const RefState *RS = state->get<RegionState>(ReallocSym); |
| if (RS) { |
| if (RS->isReleased() && ! I.getData().IsFreeOnFailure) |
| state = state->set<RegionState>(ReallocSym, |
| RefState::getAllocateUnchecked(RS->getStmt())); |
| } |
| state = state->remove<ReallocPairs>(I.getKey()); |
| } |
| } |
| |
| return state; |
| } |
| |
| // Check if the function is known to us. So, for example, we could |
| // conservatively assume it can free/reallocate it's pointer arguments. |
| // (We assume that the pointers cannot escape through calls to system |
| // functions not handled by this checker.) |
| bool MallocChecker::doesNotFreeMemory(const CallOrObjCMessage *Call, |
| ProgramStateRef State) const { |
| if (!Call) |
| return false; |
| |
| // For now, assume that any C++ call can free memory. |
| // TODO: If we want to be more optimistic here, we'll need to make sure that |
| // regions escape to C++ containers. They seem to do that even now, but for |
| // mysterious reasons. |
| if (Call->isCXXCall()) |
| return false; |
| |
| const Decl *D = Call->getDecl(); |
| if (!D) |
| return false; |
| |
| ASTContext &ASTC = State->getStateManager().getContext(); |
| |
| // If it's one of the allocation functions we can reason about, we model |
| // its behavior explicitly. |
| if (isa<FunctionDecl>(D) && isMemFunction(cast<FunctionDecl>(D), ASTC)) { |
| return true; |
| } |
| |
| // If it's not a system call, assume it frees memory. |
| SourceManager &SM = ASTC.getSourceManager(); |
| if (!SM.isInSystemHeader(D->getLocation())) |
| return false; |
| |
| // Process C/ObjC functions. |
| if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { |
| // White list the system functions whose arguments escape. |
| const IdentifierInfo *II = FD->getIdentifier(); |
| if (!II) |
| return true; |
| StringRef FName = II->getName(); |
| |
| // White list thread local storage. |
| if (FName.equals("pthread_setspecific")) |
| return false; |
| |
| // White list the 'XXXNoCopy' ObjC functions. |
| if (FName.endswith("NoCopy")) { |
| // Look for the deallocator argument. We know that the memory ownership |
| // is not transfered only if the deallocator argument is |
| // 'kCFAllocatorNull'. |
| for (unsigned i = 1; i < Call->getNumArgs(); ++i) { |
| const Expr *ArgE = Call->getArg(i)->IgnoreParenCasts(); |
| if (const DeclRefExpr *DE = dyn_cast<DeclRefExpr>(ArgE)) { |
| StringRef DeallocatorName = DE->getFoundDecl()->getName(); |
| if (DeallocatorName == "kCFAllocatorNull") |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| // PR12101 |
| // Many CoreFoundation and CoreGraphics might allow a tracked object |
| // to escape. |
| if (Call->isCFCGAllowingEscape(FName)) |
| return false; |
| |
| // Associating streams with malloced buffers. The pointer can escape if |
| // 'closefn' is specified (and if that function does free memory). |
| // Currently, we do not inspect the 'closefn' function (PR12101). |
| if (FName == "funopen") |
| if (Call->getNumArgs() >= 4 && !Call->getArgSVal(4).isConstant(0)) |
| return false; |
| |
| // Do not warn on pointers passed to 'setbuf' when used with std streams, |
| // these leaks might be intentional when setting the buffer for stdio. |
| // http://stackoverflow.com/questions/2671151/who-frees-setvbuf-buffer |
| if (FName == "setbuf" || FName =="setbuffer" || |
| FName == "setlinebuf" || FName == "setvbuf") { |
| if (Call->getNumArgs() >= 1) |
| if (const DeclRefExpr *Arg = |
| dyn_cast<DeclRefExpr>(Call->getArg(0)->IgnoreParenCasts())) |
| if (const VarDecl *D = dyn_cast<VarDecl>(Arg->getDecl())) |
| if (D->getCanonicalDecl()->getName().find("std") |
| != StringRef::npos) |
| return false; |
| } |
| |
| // A bunch of other functions, which take ownership of a pointer (See retain |
| // release checker). Not all the parameters here are invalidated, but the |
| // Malloc checker cannot differentiate between them. The right way of doing |
| // this would be to implement a pointer escapes callback. |
| if (FName == "CVPixelBufferCreateWithBytes" || |
| FName == "CGBitmapContextCreateWithData" || |
| FName == "CVPixelBufferCreateWithPlanarBytes" || |
| FName == "OSAtomicEnqueue") { |
| return false; |
| } |
| |
| // Whitelist NSXXInsertXX, for example NSMapInsertIfAbsent, since they can |
| // be deallocated by NSMapRemove. |
| if (FName.startswith("NS") && (FName.find("Insert") != StringRef::npos)) |
| return false; |
| |
| // Otherwise, assume that the function does not free memory. |
| // Most system calls, do not free the memory. |
| return true; |
| |
| // Process ObjC functions. |
| } else if (const ObjCMethodDecl * ObjCD = dyn_cast<ObjCMethodDecl>(D)) { |
| Selector S = ObjCD->getSelector(); |
| |
| // White list the ObjC functions which do free memory. |
| // - Anything containing 'freeWhenDone' param set to 1. |
| // Ex: dataWithBytesNoCopy:length:freeWhenDone. |
| for (unsigned i = 1; i < S.getNumArgs(); ++i) { |
| if (S.getNameForSlot(i).equals("freeWhenDone")) { |
| if (Call->getArgSVal(i).isConstant(1)) |
| return false; |
| else |
| return true; |
| } |
| } |
| |
| // If the first selector ends with NoCopy, assume that the ownership is |
| // transfered as well. |
| // Ex: [NSData dataWithBytesNoCopy:bytes length:10]; |
| if (S.getNameForSlot(0).endswith("NoCopy")) { |
| return false; |
| } |
| |
| // Otherwise, assume that the function does not free memory. |
| // Most system calls, do not free the memory. |
| return true; |
| } |
| |
| // Otherwise, assume that the function can free memory. |
| return false; |
| |
| } |
| |
| // If the symbol we are tracking is invalidated, but not explicitly (ex: the &p |
| // escapes, when we are tracking p), do not track the symbol as we cannot reason |
| // about it anymore. |
| ProgramStateRef |
| MallocChecker::checkRegionChanges(ProgramStateRef State, |
| const StoreManager::InvalidatedSymbols *invalidated, |
| ArrayRef<const MemRegion *> ExplicitRegions, |
| ArrayRef<const MemRegion *> Regions, |
| const CallOrObjCMessage *Call) const { |
| if (!invalidated || invalidated->empty()) |
| return State; |
| llvm::SmallPtrSet<SymbolRef, 8> WhitelistedSymbols; |
| |
| // If it's a call which might free or reallocate memory, we assume that all |
| // regions (explicit and implicit) escaped. |
| |
| // Otherwise, whitelist explicit pointers; we still can track them. |
| if (!Call || doesNotFreeMemory(Call, State)) { |
| for (ArrayRef<const MemRegion *>::iterator I = ExplicitRegions.begin(), |
| E = ExplicitRegions.end(); I != E; ++I) { |
| if (const SymbolicRegion *R = (*I)->StripCasts()->getAs<SymbolicRegion>()) |
| WhitelistedSymbols.insert(R->getSymbol()); |
| } |
| } |
| |
| for (StoreManager::InvalidatedSymbols::const_iterator I=invalidated->begin(), |
| E = invalidated->end(); I!=E; ++I) { |
| SymbolRef sym = *I; |
| if (WhitelistedSymbols.count(sym)) |
| continue; |
| // The symbol escaped. |
| if (const RefState *RS = State->get<RegionState>(sym)) |
| State = State->set<RegionState>(sym, RefState::getEscaped(RS->getStmt())); |
| } |
| return State; |
| } |
| |
| static SymbolRef findFailedReallocSymbol(ProgramStateRef currState, |
| ProgramStateRef prevState) { |
| ReallocMap currMap = currState->get<ReallocPairs>(); |
| ReallocMap prevMap = prevState->get<ReallocPairs>(); |
| |
| for (ReallocMap::iterator I = prevMap.begin(), E = prevMap.end(); |
| I != E; ++I) { |
| SymbolRef sym = I.getKey(); |
| if (!currMap.lookup(sym)) |
| return sym; |
| } |
| |
| return NULL; |
| } |
| |
| PathDiagnosticPiece * |
| MallocChecker::MallocBugVisitor::VisitNode(const ExplodedNode *N, |
| const ExplodedNode *PrevN, |
| BugReporterContext &BRC, |
| BugReport &BR) { |
| ProgramStateRef state = N->getState(); |
| ProgramStateRef statePrev = PrevN->getState(); |
| |
| const RefState *RS = state->get<RegionState>(Sym); |
| const RefState *RSPrev = statePrev->get<RegionState>(Sym); |
| if (!RS && !RSPrev) |
| return 0; |
| |
| const Stmt *S = 0; |
| const char *Msg = 0; |
| StackHintGeneratorForSymbol *StackHint = 0; |
| |
| // Retrieve the associated statement. |
| ProgramPoint ProgLoc = N->getLocation(); |
| if (isa<StmtPoint>(ProgLoc)) |
| S = cast<StmtPoint>(ProgLoc).getStmt(); |
| // If an assumption was made on a branch, it should be caught |
| // here by looking at the state transition. |
| if (isa<BlockEdge>(ProgLoc)) { |
| const CFGBlock *srcBlk = cast<BlockEdge>(ProgLoc).getSrc(); |
| S = srcBlk->getTerminator(); |
| } |
| if (!S) |
| return 0; |
| |
| // Find out if this is an interesting point and what is the kind. |
| if (Mode == Normal) { |
| if (isAllocated(RS, RSPrev, S)) { |
| Msg = "Memory is allocated"; |
| StackHint = new StackHintGeneratorForSymbol(Sym, |
| "Returned allocated memory"); |
| } else if (isReleased(RS, RSPrev, S)) { |
| Msg = "Memory is released"; |
| StackHint = new StackHintGeneratorForSymbol(Sym, |
| "Returned released memory"); |
| } else if (isReallocFailedCheck(RS, RSPrev, S)) { |
| Mode = ReallocationFailed; |
| Msg = "Reallocation failed"; |
| StackHint = new StackHintGeneratorForReallocationFailed(Sym, |
| "Reallocation failed"); |
| |
| if (SymbolRef sym = findFailedReallocSymbol(state, statePrev)) { |
| // Is it possible to fail two reallocs WITHOUT testing in between? |
| assert((!FailedReallocSymbol || FailedReallocSymbol == sym) && |
| "We only support one failed realloc at a time."); |
| BR.markInteresting(sym); |
| FailedReallocSymbol = sym; |
| } |
| } |
| |
| // We are in a special mode if a reallocation failed later in the path. |
| } else if (Mode == ReallocationFailed) { |
| assert(FailedReallocSymbol && "No symbol to look for."); |
| |
| // Is this is the first appearance of the reallocated symbol? |
| if (!statePrev->get<RegionState>(FailedReallocSymbol)) { |
| // If we ever hit this assert, that means BugReporter has decided to skip |
| // node pairs or visit them out of order. |
| assert(state->get<RegionState>(FailedReallocSymbol) && |
| "Missed the reallocation point"); |
| |
| // We're at the reallocation point. |
| Msg = "Attempt to reallocate memory"; |
| StackHint = new StackHintGeneratorForSymbol(Sym, |
| "Returned reallocated memory"); |
| FailedReallocSymbol = NULL; |
| Mode = Normal; |
| } |
| } |
| |
| if (!Msg) |
| return 0; |
| assert(StackHint); |
| |
| // Generate the extra diagnostic. |
| PathDiagnosticLocation Pos(S, BRC.getSourceManager(), |
| N->getLocationContext()); |
| return new PathDiagnosticEventPiece(Pos, Msg, true, StackHint); |
| } |
| |
| |
| #define REGISTER_CHECKER(name) \ |
| void ento::register##name(CheckerManager &mgr) {\ |
| registerCStringCheckerBasic(mgr); \ |
| mgr.registerChecker<MallocChecker>()->Filter.C##name = true;\ |
| } |
| |
| REGISTER_CHECKER(MallocPessimistic) |
| REGISTER_CHECKER(MallocOptimistic) |