| //=== 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 "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/ProgramState.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h" |
| #include "llvm/ADT/ImmutableMap.h" |
| 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 isFailed() const { return K == AllocateFailed; } |
| bool isReleased() const { return K == Released; } |
| //bool isEscaped() const { return K == Escaped; } |
| //bool isRelinquished() const { return K == Relinquished; } |
| |
| 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); |
| } |
| }; |
| |
| class RegionState {}; |
| |
| class MallocChecker : public Checker<eval::Call, |
| check::DeadSymbols, |
| check::EndPath, |
| check::PreStmt<ReturnStmt>, |
| check::Location, |
| check::Bind, |
| eval::Assume> |
| { |
| mutable llvm::OwningPtr<BuiltinBug> BT_DoubleFree; |
| mutable llvm::OwningPtr<BuiltinBug> BT_Leak; |
| mutable llvm::OwningPtr<BuiltinBug> BT_UseFree; |
| mutable llvm::OwningPtr<BuiltinBug> BT_UseRelinquished; |
| mutable llvm::OwningPtr<BuiltinBug> BT_BadFree; |
| mutable IdentifierInfo *II_malloc, *II_free, *II_realloc, *II_calloc; |
| |
| public: |
| MallocChecker() : II_malloc(0), II_free(0), II_realloc(0), II_calloc(0) {} |
| |
| bool evalCall(const CallExpr *CE, CheckerContext &C) const; |
| void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const; |
| void checkEndPath(CheckerContext &C) const; |
| void checkPreStmt(const ReturnStmt *S, CheckerContext &C) const; |
| const ProgramState *evalAssume(const ProgramState *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; |
| |
| private: |
| static void MallocMem(CheckerContext &C, const CallExpr *CE); |
| static void MallocMemReturnsAttr(CheckerContext &C, const CallExpr *CE, |
| const OwnershipAttr* Att); |
| static const ProgramState *MallocMemAux(CheckerContext &C, const CallExpr *CE, |
| const Expr *SizeEx, SVal Init, |
| const ProgramState *state) { |
| return MallocMemAux(C, CE, state->getSVal(SizeEx), Init, state); |
| } |
| static const ProgramState *MallocMemAux(CheckerContext &C, const CallExpr *CE, |
| SVal SizeEx, SVal Init, |
| const ProgramState *state); |
| |
| void FreeMem(CheckerContext &C, const CallExpr *CE) const; |
| void FreeMemAttr(CheckerContext &C, const CallExpr *CE, |
| const OwnershipAttr* Att) const; |
| const ProgramState *FreeMemAux(CheckerContext &C, const CallExpr *CE, |
| const ProgramState *state, unsigned Num, |
| bool Hold) const; |
| |
| void ReallocMem(CheckerContext &C, const CallExpr *CE) const; |
| static void CallocMem(CheckerContext &C, const CallExpr *CE); |
| |
| 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; |
| }; |
| } // end anonymous namespace |
| |
| typedef llvm::ImmutableMap<SymbolRef, RefState> RegionStateTy; |
| |
| namespace clang { |
| namespace ento { |
| template <> |
| struct ProgramStateTrait<RegionState> |
| : public ProgramStatePartialTrait<RegionStateTy> { |
| static void *GDMIndex() { static int x; return &x; } |
| }; |
| } |
| } |
| |
| bool MallocChecker::evalCall(const CallExpr *CE, CheckerContext &C) const { |
| const FunctionDecl *FD = C.getCalleeDecl(CE); |
| if (!FD) |
| return false; |
| |
| ASTContext &Ctx = C.getASTContext(); |
| 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_calloc) |
| II_calloc = &Ctx.Idents.get("calloc"); |
| |
| if (FD->getIdentifier() == II_malloc) { |
| MallocMem(C, CE); |
| return true; |
| } |
| |
| if (FD->getIdentifier() == II_free) { |
| FreeMem(C, CE); |
| return true; |
| } |
| |
| if (FD->getIdentifier() == II_realloc) { |
| ReallocMem(C, CE); |
| return true; |
| } |
| |
| if (FD->getIdentifier() == II_calloc) { |
| CallocMem(C, CE); |
| return true; |
| } |
| |
| // Check all the attributes, if there are any. |
| // There can be multiple of these attributes. |
| bool rv = false; |
| 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: { |
| MallocMemReturnsAttr(C, CE, *i); |
| rv = true; |
| break; |
| } |
| case OwnershipAttr::Takes: |
| case OwnershipAttr::Holds: { |
| FreeMemAttr(C, CE, *i); |
| rv = true; |
| break; |
| } |
| default: |
| break; |
| } |
| } |
| } |
| return rv; |
| } |
| |
| void MallocChecker::MallocMem(CheckerContext &C, const CallExpr *CE) { |
| const ProgramState *state = MallocMemAux(C, CE, CE->getArg(0), UndefinedVal(), |
| C.getState()); |
| C.addTransition(state); |
| } |
| |
| void MallocChecker::MallocMemReturnsAttr(CheckerContext &C, const CallExpr *CE, |
| const OwnershipAttr* Att) { |
| if (Att->getModule() != "malloc") |
| return; |
| |
| OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end(); |
| if (I != E) { |
| const ProgramState *state = |
| MallocMemAux(C, CE, CE->getArg(*I), UndefinedVal(), C.getState()); |
| C.addTransition(state); |
| return; |
| } |
| const ProgramState *state = MallocMemAux(C, CE, UnknownVal(), UndefinedVal(), |
| C.getState()); |
| C.addTransition(state); |
| } |
| |
| const ProgramState *MallocChecker::MallocMemAux(CheckerContext &C, |
| const CallExpr *CE, |
| SVal Size, SVal Init, |
| const ProgramState *state) { |
| unsigned Count = C.getCurrentBlockCount(); |
| SValBuilder &svalBuilder = C.getSValBuilder(); |
| |
| // Set the return value. |
| SVal retVal = svalBuilder.getConjuredSymbolVal(NULL, CE, |
| CE->getType(), Count); |
| state = state->BindExpr(CE, retVal); |
| |
| // 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 = cast<SymbolicRegion>(retVal.getAsRegion()); |
| DefinedOrUnknownSVal Extent = R->getExtent(svalBuilder); |
| DefinedOrUnknownSVal DefinedSize = cast<DefinedOrUnknownSVal>(Size); |
| DefinedOrUnknownSVal extentMatchesSize = |
| svalBuilder.evalEQ(state, Extent, DefinedSize); |
| |
| state = state->assume(extentMatchesSize, true); |
| assert(state); |
| |
| SymbolRef Sym = retVal.getAsLocSymbol(); |
| assert(Sym); |
| |
| // Set the symbol's state to Allocated. |
| return state->set<RegionState>(Sym, RefState::getAllocateUnchecked(CE)); |
| } |
| |
| void MallocChecker::FreeMem(CheckerContext &C, const CallExpr *CE) const { |
| const ProgramState *state = FreeMemAux(C, CE, C.getState(), 0, false); |
| |
| if (state) |
| C.addTransition(state); |
| } |
| |
| void MallocChecker::FreeMemAttr(CheckerContext &C, const CallExpr *CE, |
| const OwnershipAttr* Att) const { |
| if (Att->getModule() != "malloc") |
| return; |
| |
| for (OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end(); |
| I != E; ++I) { |
| const ProgramState *state = |
| FreeMemAux(C, CE, C.getState(), *I, |
| Att->getOwnKind() == OwnershipAttr::Holds); |
| if (state) |
| C.addTransition(state); |
| } |
| } |
| |
| const ProgramState *MallocChecker::FreeMemAux(CheckerContext &C, |
| const CallExpr *CE, |
| const ProgramState *state, |
| unsigned Num, |
| bool Hold) const { |
| const Expr *ArgExpr = CE->getArg(Num); |
| SVal ArgVal = state->getSVal(ArgExpr); |
| |
| DefinedOrUnknownSVal location = cast<DefinedOrUnknownSVal>(ArgVal); |
| |
| // Check for null dereferences. |
| if (!isa<Loc>(location)) |
| return state; |
| |
| // FIXME: Technically using 'Assume' here can result in a path |
| // bifurcation. In such cases we need to return two states, not just one. |
| const ProgramState *notNullState, *nullState; |
| llvm::tie(notNullState, nullState) = state->assume(location); |
| |
| // The explicit NULL case, no operation is performed. |
| if (nullState && !notNullState) |
| return nullState; |
| |
| assert(notNullState); |
| |
| // Unknown values could easily be okay |
| // Undefined values are handled elsewhere |
| if (ArgVal.isUnknownOrUndef()) |
| return notNullState; |
| |
| 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 NULL; |
| } |
| |
| 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 NULL; |
| } |
| |
| 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 NULL; |
| } |
| |
| const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R); |
| // Various cases could lead to non-symbol values here. |
| // For now, ignore them. |
| if (!SR) |
| return notNullState; |
| |
| 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 notNullState; |
| |
| // Check double free. |
| if (RS->isReleased()) { |
| if (ExplodedNode *N = C.generateSink()) { |
| if (!BT_DoubleFree) |
| BT_DoubleFree.reset( |
| new BuiltinBug("Double free", |
| "Try to free a memory block that has been released")); |
| // FIXME: should find where it's freed last time. |
| BugReport *R = new BugReport(*BT_DoubleFree, |
| BT_DoubleFree->getDescription(), N); |
| C.EmitReport(R); |
| } |
| return NULL; |
| } |
| |
| // Normal free. |
| if (Hold) |
| return notNullState->set<RegionState>(Sym, RefState::getRelinquished(CE)); |
| return notNullState->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(); |
| |
| switch (MS->getKind()) { |
| case MemRegion::StackLocalsSpaceRegionKind: { |
| 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; |
| } |
| case MemRegion::StackArgumentsSpaceRegionKind: { |
| 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; |
| } |
| case MemRegion::NonStaticGlobalSpaceRegionKind: |
| case MemRegion::StaticGlobalSpaceRegionKind: { |
| 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; |
| } |
| default: |
| return false; |
| } |
| } |
| } |
| } |
| |
| void MallocChecker::ReportBadFree(CheckerContext &C, SVal ArgVal, |
| SourceRange range) const { |
| if (ExplodedNode *N = C.generateSink()) { |
| if (!BT_BadFree) |
| BT_BadFree.reset(new BuiltinBug("Bad free")); |
| |
| llvm::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->addRange(range); |
| C.EmitReport(R); |
| } |
| } |
| |
| void MallocChecker::ReallocMem(CheckerContext &C, const CallExpr *CE) const { |
| const ProgramState *state = C.getState(); |
| const Expr *arg0Expr = CE->getArg(0); |
| DefinedOrUnknownSVal arg0Val |
| = cast<DefinedOrUnknownSVal>(state->getSVal(arg0Expr)); |
| |
| 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; |
| |
| // Get the value of the size argument. |
| DefinedOrUnknownSVal Arg1Val = |
| cast<DefinedOrUnknownSVal>(state->getSVal(Arg1)); |
| |
| // Compare the size argument to 0. |
| DefinedOrUnknownSVal SizeZero = |
| svalBuilder.evalEQ(state, Arg1Val, |
| svalBuilder.makeIntValWithPtrWidth(0, false)); |
| |
| // If the ptr is NULL and the size is not 0, the call is equivalent to |
| // malloc(size). |
| const ProgramState *stateEqual = state->assume(PtrEQ, true); |
| if (stateEqual && state->assume(SizeZero, false)) { |
| // Hack: set the NULL symbolic region to released to suppress false warning. |
| // In the future we should add more states for allocated regions, e.g., |
| // CheckedNull, CheckedNonNull. |
| |
| SymbolRef Sym = arg0Val.getAsLocSymbol(); |
| if (Sym) |
| stateEqual = stateEqual->set<RegionState>(Sym, RefState::getReleased(CE)); |
| |
| const ProgramState *stateMalloc = MallocMemAux(C, CE, CE->getArg(1), |
| UndefinedVal(), stateEqual); |
| C.addTransition(stateMalloc); |
| } |
| |
| if (const ProgramState *stateNotEqual = state->assume(PtrEQ, false)) { |
| // If the size is 0, free the memory. |
| if (const ProgramState *stateSizeZero = |
| stateNotEqual->assume(SizeZero, true)) |
| if (const ProgramState *stateFree = |
| FreeMemAux(C, CE, stateSizeZero, 0, false)) { |
| |
| // Bind the return value to NULL because it is now free. |
| C.addTransition(stateFree->BindExpr(CE, svalBuilder.makeNull(), true)); |
| } |
| if (const ProgramState *stateSizeNotZero = |
| stateNotEqual->assume(SizeZero,false)) |
| if (const ProgramState *stateFree = FreeMemAux(C, CE, stateSizeNotZero, |
| 0, false)) { |
| // FIXME: We should copy the content of the original buffer. |
| const ProgramState *stateRealloc = MallocMemAux(C, CE, CE->getArg(1), |
| UnknownVal(), stateFree); |
| C.addTransition(stateRealloc); |
| } |
| } |
| } |
| |
| void MallocChecker::CallocMem(CheckerContext &C, const CallExpr *CE) { |
| const ProgramState *state = C.getState(); |
| SValBuilder &svalBuilder = C.getSValBuilder(); |
| |
| SVal count = state->getSVal(CE->getArg(0)); |
| SVal elementSize = state->getSVal(CE->getArg(1)); |
| SVal TotalSize = svalBuilder.evalBinOp(state, BO_Mul, count, elementSize, |
| svalBuilder.getContext().getSizeType()); |
| SVal zeroVal = svalBuilder.makeZeroVal(svalBuilder.getContext().CharTy); |
| |
| C.addTransition(MallocMemAux(C, CE, TotalSize, zeroVal, state)); |
| } |
| |
| void MallocChecker::checkDeadSymbols(SymbolReaper &SymReaper, |
| CheckerContext &C) const |
| { |
| if (!SymReaper.hasDeadSymbols()) |
| return; |
| |
| const ProgramState *state = C.getState(); |
| RegionStateTy RS = state->get<RegionState>(); |
| RegionStateTy::Factory &F = state->get_context<RegionState>(); |
| |
| bool generateReport = false; |
| |
| for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) { |
| if (SymReaper.isDead(I->first)) { |
| if (I->second.isAllocated()) |
| generateReport = true; |
| |
| // Remove the dead symbol from the map. |
| RS = F.remove(RS, I->first); |
| |
| } |
| } |
| |
| ExplodedNode *N = C.addTransition(state->set<RegionState>(RS)); |
| |
| // FIXME: This does not handle when we have multiple leaks at a single |
| // place. |
| if (N && generateReport) { |
| if (!BT_Leak) |
| BT_Leak.reset(new BuiltinBug("Memory leak", |
| "Allocated memory never released. Potential memory leak.")); |
| // FIXME: where it is allocated. |
| BugReport *R = new BugReport(*BT_Leak, BT_Leak->getDescription(), N); |
| C.EmitReport(R); |
| } |
| } |
| |
| void MallocChecker::checkEndPath(CheckerContext &Ctx) const { |
| const ProgramState *state = Ctx.getState(); |
| RegionStateTy M = state->get<RegionState>(); |
| |
| for (RegionStateTy::iterator I = M.begin(), E = M.end(); I != E; ++I) { |
| RefState RS = I->second; |
| if (RS.isAllocated()) { |
| ExplodedNode *N = Ctx.addTransition(state); |
| if (N) { |
| if (!BT_Leak) |
| BT_Leak.reset(new BuiltinBug("Memory leak", |
| "Allocated memory never released. Potential memory leak.")); |
| BugReport *R = new BugReport(*BT_Leak, BT_Leak->getDescription(), N); |
| Ctx.EmitReport(R); |
| } |
| } |
| } |
| } |
| |
| void MallocChecker::checkPreStmt(const ReturnStmt *S, CheckerContext &C) const { |
| const Expr *retExpr = S->getRetValue(); |
| if (!retExpr) |
| return; |
| |
| const ProgramState *state = C.getState(); |
| |
| SymbolRef Sym = state->getSVal(retExpr).getAsSymbol(); |
| if (!Sym) |
| return; |
| |
| const RefState *RS = state->get<RegionState>(Sym); |
| if (!RS) |
| return; |
| |
| // FIXME: check other cases. |
| if (RS->isAllocated()) |
| state = state->set<RegionState>(Sym, RefState::getEscaped(S)); |
| |
| C.addTransition(state); |
| } |
| |
| const ProgramState *MallocChecker::evalAssume(const ProgramState *state, |
| SVal Cond, |
| bool Assumption) const { |
| // If a symblic region is assumed to NULL, set its state to AllocateFailed. |
| // FIXME: should also check symbols assumed to non-null. |
| |
| RegionStateTy RS = state->get<RegionState>(); |
| |
| for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) { |
| // If the symbol is assumed to NULL, this will return an APSInt*. |
| if (state->getSymVal(I.getKey())) |
| state = state->set<RegionState>(I.getKey(),RefState::getAllocateFailed()); |
| } |
| |
| return state; |
| } |
| |
| // 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) { |
| const RefState *RS = C.getState()->get<RegionState>(Sym); |
| if (RS && RS->isReleased()) { |
| if (ExplodedNode *N = C.addTransition()) { |
| if (!BT_UseFree) |
| BT_UseFree.reset(new BuiltinBug("Use dynamically allocated memory " |
| "after it is freed.")); |
| |
| BugReport *R = new BugReport(*BT_UseFree, BT_UseFree->getDescription(), |
| N); |
| C.EmitReport(R); |
| } |
| } |
| } |
| } |
| |
| void MallocChecker::checkBind(SVal location, SVal val, |
| const Stmt *BindS, CheckerContext &C) const { |
| // The PreVisitBind implements the same algorithm as already used by the |
| // Objective C ownership checker: if the pointer escaped from this scope by |
| // assignment, let it go. However, assigning to fields of a stack-storage |
| // structure does not transfer ownership. |
| |
| const ProgramState *state = C.getState(); |
| DefinedOrUnknownSVal l = cast<DefinedOrUnknownSVal>(location); |
| |
| // Check for null dereferences. |
| if (!isa<Loc>(l)) |
| return; |
| |
| // Before checking if the state is null, check if 'val' has a RefState. |
| // Only then should we check for null and bifurcate the state. |
| SymbolRef Sym = val.getLocSymbolInBase(); |
| if (Sym) { |
| if (const RefState *RS = state->get<RegionState>(Sym)) { |
| // If ptr is NULL, no operation is performed. |
| const ProgramState *notNullState, *nullState; |
| llvm::tie(notNullState, nullState) = state->assume(l); |
| |
| // Generate a transition for 'nullState' to record the assumption |
| // that the state was null. |
| if (nullState) |
| C.addTransition(nullState); |
| |
| if (!notNullState) |
| return; |
| |
| if (RS->isAllocated()) { |
| // Something we presently own is being assigned somewhere. |
| const MemRegion *AR = location.getAsRegion(); |
| if (!AR) |
| return; |
| AR = AR->StripCasts()->getBaseRegion(); |
| do { |
| // If it is on the stack, we still own it. |
| if (AR->hasStackNonParametersStorage()) |
| break; |
| |
| // If the state can't represent this binding, we still own it. |
| if (notNullState == (notNullState->bindLoc(cast<Loc>(location), |
| UnknownVal()))) |
| break; |
| |
| // We no longer own this pointer. |
| notNullState = |
| notNullState->set<RegionState>(Sym, |
| RefState::getRelinquished(BindS)); |
| } |
| while (false); |
| } |
| C.addTransition(notNullState); |
| } |
| } |
| } |
| |
| void ento::registerMallocChecker(CheckerManager &mgr) { |
| mgr.registerChecker<MallocChecker>(); |
| } |
