| //= CStringChecker.h - Checks calls to C string functions ----------*- C++ -*-// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This defines CStringChecker, which is an assortment of checks on calls |
| // to functions in <string.h>. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "GRExprEngineExperimentalChecks.h" |
| #include "clang/Checker/BugReporter/BugType.h" |
| #include "clang/Checker/PathSensitive/CheckerVisitor.h" |
| #include "clang/Checker/PathSensitive/GRStateTrait.h" |
| #include "llvm/ADT/StringSwitch.h" |
| |
| using namespace clang; |
| |
| namespace { |
| class CStringChecker : public CheckerVisitor<CStringChecker> { |
| BugType *BT_Null, *BT_Bounds, *BT_BoundsWrite, *BT_Overlap, *BT_NotCString; |
| public: |
| CStringChecker() |
| : BT_Null(0), BT_Bounds(0), BT_BoundsWrite(0), BT_Overlap(0), BT_NotCString(0) |
| {} |
| static void *getTag() { static int tag; return &tag; } |
| |
| bool EvalCallExpr(CheckerContext &C, const CallExpr *CE); |
| void PreVisitDeclStmt(CheckerContext &C, const DeclStmt *DS); |
| void MarkLiveSymbols(const GRState *state, SymbolReaper &SR); |
| void EvalDeadSymbols(CheckerContext &C, SymbolReaper &SR); |
| bool WantsRegionChangeUpdate(const GRState *state); |
| |
| const GRState *EvalRegionChanges(const GRState *state, |
| const MemRegion * const *Begin, |
| const MemRegion * const *End, |
| bool*); |
| |
| typedef void (CStringChecker::*FnCheck)(CheckerContext &, const CallExpr *); |
| |
| void EvalMemcpy(CheckerContext &C, const CallExpr *CE); |
| void EvalMemmove(CheckerContext &C, const CallExpr *CE); |
| void EvalBcopy(CheckerContext &C, const CallExpr *CE); |
| void EvalCopyCommon(CheckerContext &C, const GRState *state, |
| const Expr *Size, const Expr *Source, const Expr *Dest, |
| bool Restricted = false); |
| |
| void EvalMemcmp(CheckerContext &C, const CallExpr *CE); |
| |
| void EvalStrlen(CheckerContext &C, const CallExpr *CE); |
| |
| void EvalStrcpy(CheckerContext &C, const CallExpr *CE); |
| void EvalStpcpy(CheckerContext &C, const CallExpr *CE); |
| void EvalStrcpyCommon(CheckerContext &C, const CallExpr *CE, bool ReturnEnd); |
| |
| // Utility methods |
| std::pair<const GRState*, const GRState*> |
| AssumeZero(CheckerContext &C, const GRState *state, SVal V, QualType Ty); |
| |
| const GRState *SetCStringLength(const GRState *state, const MemRegion *MR, |
| SVal StrLen); |
| SVal GetCStringLengthForRegion(CheckerContext &C, const GRState *&state, |
| const Expr *Ex, const MemRegion *MR); |
| SVal GetCStringLength(CheckerContext &C, const GRState *&state, |
| const Expr *Ex, SVal Buf); |
| |
| const GRState *InvalidateBuffer(CheckerContext &C, const GRState *state, |
| const Expr *Ex, SVal V); |
| |
| bool SummarizeRegion(llvm::raw_ostream& os, ASTContext& Ctx, |
| const MemRegion *MR); |
| |
| // Re-usable checks |
| const GRState *CheckNonNull(CheckerContext &C, const GRState *state, |
| const Expr *S, SVal l); |
| const GRState *CheckLocation(CheckerContext &C, const GRState *state, |
| const Expr *S, SVal l, |
| bool IsDestination = false); |
| const GRState *CheckBufferAccess(CheckerContext &C, const GRState *state, |
| const Expr *Size, |
| const Expr *FirstBuf, |
| const Expr *SecondBuf = NULL, |
| bool FirstIsDestination = false); |
| const GRState *CheckOverlap(CheckerContext &C, const GRState *state, |
| const Expr *Size, const Expr *First, |
| const Expr *Second); |
| void EmitOverlapBug(CheckerContext &C, const GRState *state, |
| const Stmt *First, const Stmt *Second); |
| }; |
| |
| class CStringLength { |
| public: |
| typedef llvm::ImmutableMap<const MemRegion *, SVal> EntryMap; |
| }; |
| } //end anonymous namespace |
| |
| namespace clang { |
| template <> |
| struct GRStateTrait<CStringLength> |
| : public GRStatePartialTrait<CStringLength::EntryMap> { |
| static void *GDMIndex() { return CStringChecker::getTag(); } |
| }; |
| } |
| |
| void clang::RegisterCStringChecker(GRExprEngine &Eng) { |
| Eng.registerCheck(new CStringChecker()); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Individual checks and utility methods. |
| //===----------------------------------------------------------------------===// |
| |
| std::pair<const GRState*, const GRState*> |
| CStringChecker::AssumeZero(CheckerContext &C, const GRState *state, SVal V, |
| QualType Ty) { |
| DefinedSVal *Val = dyn_cast<DefinedSVal>(&V); |
| if (!Val) |
| return std::pair<const GRState*, const GRState *>(state, state); |
| |
| ValueManager &ValMgr = C.getValueManager(); |
| SValuator &SV = ValMgr.getSValuator(); |
| |
| DefinedOrUnknownSVal Zero = ValMgr.makeZeroVal(Ty); |
| DefinedOrUnknownSVal ValIsZero = SV.EvalEQ(state, *Val, Zero); |
| |
| return state->Assume(ValIsZero); |
| } |
| |
| const GRState *CStringChecker::CheckNonNull(CheckerContext &C, |
| const GRState *state, |
| const Expr *S, SVal l) { |
| // If a previous check has failed, propagate the failure. |
| if (!state) |
| return NULL; |
| |
| const GRState *stateNull, *stateNonNull; |
| llvm::tie(stateNull, stateNonNull) = AssumeZero(C, state, l, S->getType()); |
| |
| if (stateNull && !stateNonNull) { |
| ExplodedNode *N = C.GenerateSink(stateNull); |
| if (!N) |
| return NULL; |
| |
| if (!BT_Null) |
| BT_Null = new BuiltinBug("API", |
| "Null pointer argument in call to byte string function"); |
| |
| // Generate a report for this bug. |
| BuiltinBug *BT = static_cast<BuiltinBug*>(BT_Null); |
| EnhancedBugReport *report = new EnhancedBugReport(*BT, |
| BT->getDescription(), N); |
| |
| report->addRange(S->getSourceRange()); |
| report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, S); |
| C.EmitReport(report); |
| return NULL; |
| } |
| |
| // From here on, assume that the value is non-null. |
| assert(stateNonNull); |
| return stateNonNull; |
| } |
| |
| // FIXME: This was originally copied from ArrayBoundChecker.cpp. Refactor? |
| const GRState *CStringChecker::CheckLocation(CheckerContext &C, |
| const GRState *state, |
| const Expr *S, SVal l, |
| bool IsDestination) { |
| // If a previous check has failed, propagate the failure. |
| if (!state) |
| return NULL; |
| |
| // Check for out of bound array element access. |
| const MemRegion *R = l.getAsRegion(); |
| if (!R) |
| return state; |
| |
| const ElementRegion *ER = dyn_cast<ElementRegion>(R); |
| if (!ER) |
| return state; |
| |
| assert(ER->getValueType() == C.getASTContext().CharTy && |
| "CheckLocation should only be called with char* ElementRegions"); |
| |
| // Get the size of the array. |
| const SubRegion *Super = cast<SubRegion>(ER->getSuperRegion()); |
| ValueManager &ValMgr = C.getValueManager(); |
| SVal Extent = ValMgr.convertToArrayIndex(Super->getExtent(ValMgr)); |
| DefinedOrUnknownSVal Size = cast<DefinedOrUnknownSVal>(Extent); |
| |
| // Get the index of the accessed element. |
| DefinedOrUnknownSVal Idx = cast<DefinedOrUnknownSVal>(ER->getIndex()); |
| |
| const GRState *StInBound = state->AssumeInBound(Idx, Size, true); |
| const GRState *StOutBound = state->AssumeInBound(Idx, Size, false); |
| if (StOutBound && !StInBound) { |
| ExplodedNode *N = C.GenerateSink(StOutBound); |
| if (!N) |
| return NULL; |
| |
| BuiltinBug *BT; |
| if (IsDestination) { |
| if (!BT_BoundsWrite) { |
| BT_BoundsWrite = new BuiltinBug("Out-of-bound array access", |
| "Byte string function overflows destination buffer"); |
| } |
| BT = static_cast<BuiltinBug*>(BT_BoundsWrite); |
| } else { |
| if (!BT_Bounds) { |
| BT_Bounds = new BuiltinBug("Out-of-bound array access", |
| "Byte string function accesses out-of-bound array element"); |
| } |
| BT = static_cast<BuiltinBug*>(BT_Bounds); |
| } |
| |
| // FIXME: It would be nice to eventually make this diagnostic more clear, |
| // e.g., by referencing the original declaration or by saying *why* this |
| // reference is outside the range. |
| |
| // Generate a report for this bug. |
| RangedBugReport *report = new RangedBugReport(*BT, BT->getDescription(), N); |
| |
| report->addRange(S->getSourceRange()); |
| C.EmitReport(report); |
| return NULL; |
| } |
| |
| // Array bound check succeeded. From this point forward the array bound |
| // should always succeed. |
| return StInBound; |
| } |
| |
| const GRState *CStringChecker::CheckBufferAccess(CheckerContext &C, |
| const GRState *state, |
| const Expr *Size, |
| const Expr *FirstBuf, |
| const Expr *SecondBuf, |
| bool FirstIsDestination) { |
| // If a previous check has failed, propagate the failure. |
| if (!state) |
| return NULL; |
| |
| ValueManager &VM = C.getValueManager(); |
| SValuator &SV = VM.getSValuator(); |
| ASTContext &Ctx = C.getASTContext(); |
| |
| QualType SizeTy = Size->getType(); |
| QualType PtrTy = Ctx.getPointerType(Ctx.CharTy); |
| |
| // Check that the first buffer is non-null. |
| SVal BufVal = state->getSVal(FirstBuf); |
| state = CheckNonNull(C, state, FirstBuf, BufVal); |
| if (!state) |
| return NULL; |
| |
| // Get the access length and make sure it is known. |
| SVal LengthVal = state->getSVal(Size); |
| NonLoc *Length = dyn_cast<NonLoc>(&LengthVal); |
| if (!Length) |
| return state; |
| |
| // Compute the offset of the last element to be accessed: size-1. |
| NonLoc One = cast<NonLoc>(VM.makeIntVal(1, SizeTy)); |
| NonLoc LastOffset = cast<NonLoc>(SV.EvalBinOpNN(state, BO_Sub, |
| *Length, One, SizeTy)); |
| |
| // Check that the first buffer is sufficently long. |
| SVal BufStart = SV.EvalCast(BufVal, PtrTy, FirstBuf->getType()); |
| if (Loc *BufLoc = dyn_cast<Loc>(&BufStart)) { |
| SVal BufEnd = SV.EvalBinOpLN(state, BO_Add, *BufLoc, |
| LastOffset, PtrTy); |
| state = CheckLocation(C, state, FirstBuf, BufEnd, FirstIsDestination); |
| |
| // If the buffer isn't large enough, abort. |
| if (!state) |
| return NULL; |
| } |
| |
| // If there's a second buffer, check it as well. |
| if (SecondBuf) { |
| BufVal = state->getSVal(SecondBuf); |
| state = CheckNonNull(C, state, SecondBuf, BufVal); |
| if (!state) |
| return NULL; |
| |
| BufStart = SV.EvalCast(BufVal, PtrTy, SecondBuf->getType()); |
| if (Loc *BufLoc = dyn_cast<Loc>(&BufStart)) { |
| SVal BufEnd = SV.EvalBinOpLN(state, BO_Add, *BufLoc, |
| LastOffset, PtrTy); |
| state = CheckLocation(C, state, SecondBuf, BufEnd); |
| } |
| } |
| |
| // Large enough or not, return this state! |
| return state; |
| } |
| |
| const GRState *CStringChecker::CheckOverlap(CheckerContext &C, |
| const GRState *state, |
| const Expr *Size, |
| const Expr *First, |
| const Expr *Second) { |
| // Do a simple check for overlap: if the two arguments are from the same |
| // buffer, see if the end of the first is greater than the start of the second |
| // or vice versa. |
| |
| // If a previous check has failed, propagate the failure. |
| if (!state) |
| return NULL; |
| |
| ValueManager &VM = state->getStateManager().getValueManager(); |
| SValuator &SV = VM.getSValuator(); |
| ASTContext &Ctx = VM.getContext(); |
| const GRState *stateTrue, *stateFalse; |
| |
| // Get the buffer values and make sure they're known locations. |
| SVal FirstVal = state->getSVal(First); |
| SVal SecondVal = state->getSVal(Second); |
| |
| Loc *FirstLoc = dyn_cast<Loc>(&FirstVal); |
| if (!FirstLoc) |
| return state; |
| |
| Loc *SecondLoc = dyn_cast<Loc>(&SecondVal); |
| if (!SecondLoc) |
| return state; |
| |
| // Are the two values the same? |
| DefinedOrUnknownSVal EqualTest = SV.EvalEQ(state, *FirstLoc, *SecondLoc); |
| llvm::tie(stateTrue, stateFalse) = state->Assume(EqualTest); |
| |
| if (stateTrue && !stateFalse) { |
| // If the values are known to be equal, that's automatically an overlap. |
| EmitOverlapBug(C, stateTrue, First, Second); |
| return NULL; |
| } |
| |
| // Assume the two expressions are not equal. |
| assert(stateFalse); |
| state = stateFalse; |
| |
| // Which value comes first? |
| QualType CmpTy = Ctx.IntTy; |
| SVal Reverse = SV.EvalBinOpLL(state, BO_GT, |
| *FirstLoc, *SecondLoc, CmpTy); |
| DefinedOrUnknownSVal *ReverseTest = dyn_cast<DefinedOrUnknownSVal>(&Reverse); |
| if (!ReverseTest) |
| return state; |
| |
| llvm::tie(stateTrue, stateFalse) = state->Assume(*ReverseTest); |
| |
| if (stateTrue) { |
| if (stateFalse) { |
| // If we don't know which one comes first, we can't perform this test. |
| return state; |
| } else { |
| // Switch the values so that FirstVal is before SecondVal. |
| Loc *tmpLoc = FirstLoc; |
| FirstLoc = SecondLoc; |
| SecondLoc = tmpLoc; |
| |
| // Switch the Exprs as well, so that they still correspond. |
| const Expr *tmpExpr = First; |
| First = Second; |
| Second = tmpExpr; |
| } |
| } |
| |
| // Get the length, and make sure it too is known. |
| SVal LengthVal = state->getSVal(Size); |
| NonLoc *Length = dyn_cast<NonLoc>(&LengthVal); |
| if (!Length) |
| return state; |
| |
| // Convert the first buffer's start address to char*. |
| // Bail out if the cast fails. |
| QualType CharPtrTy = Ctx.getPointerType(Ctx.CharTy); |
| SVal FirstStart = SV.EvalCast(*FirstLoc, CharPtrTy, First->getType()); |
| Loc *FirstStartLoc = dyn_cast<Loc>(&FirstStart); |
| if (!FirstStartLoc) |
| return state; |
| |
| // Compute the end of the first buffer. Bail out if THAT fails. |
| SVal FirstEnd = SV.EvalBinOpLN(state, BO_Add, |
| *FirstStartLoc, *Length, CharPtrTy); |
| Loc *FirstEndLoc = dyn_cast<Loc>(&FirstEnd); |
| if (!FirstEndLoc) |
| return state; |
| |
| // Is the end of the first buffer past the start of the second buffer? |
| SVal Overlap = SV.EvalBinOpLL(state, BO_GT, |
| *FirstEndLoc, *SecondLoc, CmpTy); |
| DefinedOrUnknownSVal *OverlapTest = dyn_cast<DefinedOrUnknownSVal>(&Overlap); |
| if (!OverlapTest) |
| return state; |
| |
| llvm::tie(stateTrue, stateFalse) = state->Assume(*OverlapTest); |
| |
| if (stateTrue && !stateFalse) { |
| // Overlap! |
| EmitOverlapBug(C, stateTrue, First, Second); |
| return NULL; |
| } |
| |
| // Assume the two expressions don't overlap. |
| assert(stateFalse); |
| return stateFalse; |
| } |
| |
| void CStringChecker::EmitOverlapBug(CheckerContext &C, const GRState *state, |
| const Stmt *First, const Stmt *Second) { |
| ExplodedNode *N = C.GenerateSink(state); |
| if (!N) |
| return; |
| |
| if (!BT_Overlap) |
| BT_Overlap = new BugType("Unix API", "Improper arguments"); |
| |
| // Generate a report for this bug. |
| RangedBugReport *report = |
| new RangedBugReport(*BT_Overlap, |
| "Arguments must not be overlapping buffers", N); |
| report->addRange(First->getSourceRange()); |
| report->addRange(Second->getSourceRange()); |
| |
| C.EmitReport(report); |
| } |
| |
| const GRState *CStringChecker::SetCStringLength(const GRState *state, |
| const MemRegion *MR, |
| SVal StrLen) { |
| assert(!StrLen.isUndef() && "Attempt to set an undefined string length"); |
| if (StrLen.isUnknown()) |
| return state; |
| |
| MR = MR->StripCasts(); |
| |
| switch (MR->getKind()) { |
| case MemRegion::StringRegionKind: |
| // FIXME: This can happen if we strcpy() into a string region. This is |
| // undefined [C99 6.4.5p6], but we should still warn about it. |
| return state; |
| |
| case MemRegion::SymbolicRegionKind: |
| case MemRegion::AllocaRegionKind: |
| case MemRegion::VarRegionKind: |
| case MemRegion::FieldRegionKind: |
| case MemRegion::ObjCIvarRegionKind: |
| return state->set<CStringLength>(MR, StrLen); |
| |
| case MemRegion::ElementRegionKind: |
| // FIXME: Handle element regions by upper-bounding the parent region's |
| // string length. |
| return state; |
| |
| default: |
| // Other regions (mostly non-data) can't have a reliable C string length. |
| // For now, just ignore the change. |
| // FIXME: These are rare but not impossible. We should output some kind of |
| // warning for things like strcpy((char[]){'a', 0}, "b"); |
| return state; |
| } |
| } |
| |
| SVal CStringChecker::GetCStringLengthForRegion(CheckerContext &C, |
| const GRState *&state, |
| const Expr *Ex, |
| const MemRegion *MR) { |
| // If there's a recorded length, go ahead and return it. |
| const SVal *Recorded = state->get<CStringLength>(MR); |
| if (Recorded) |
| return *Recorded; |
| |
| // Otherwise, get a new symbol and update the state. |
| unsigned Count = C.getNodeBuilder().getCurrentBlockCount(); |
| ValueManager &ValMgr = C.getValueManager(); |
| QualType SizeTy = ValMgr.getContext().getSizeType(); |
| SVal Strlen = ValMgr.getMetadataSymbolVal(getTag(), MR, Ex, SizeTy, Count); |
| |
| state = state->set<CStringLength>(MR, Strlen); |
| return Strlen; |
| } |
| |
| SVal CStringChecker::GetCStringLength(CheckerContext &C, const GRState *&state, |
| const Expr *Ex, SVal Buf) { |
| const MemRegion *MR = Buf.getAsRegion(); |
| if (!MR) { |
| // If we can't get a region, see if it's something we /know/ isn't a |
| // C string. In the context of locations, the only time we can issue such |
| // a warning is for labels. |
| if (loc::GotoLabel *Label = dyn_cast<loc::GotoLabel>(&Buf)) { |
| if (ExplodedNode *N = C.GenerateNode(state)) { |
| if (!BT_NotCString) |
| BT_NotCString = new BuiltinBug("API", |
| "Argument is not a null-terminated string."); |
| |
| llvm::SmallString<120> buf; |
| llvm::raw_svector_ostream os(buf); |
| os << "Argument to byte string function is the address of the label '" |
| << Label->getLabel()->getID()->getName() |
| << "', which is not a null-terminated string"; |
| |
| // Generate a report for this bug. |
| EnhancedBugReport *report = new EnhancedBugReport(*BT_NotCString, |
| os.str(), N); |
| |
| report->addRange(Ex->getSourceRange()); |
| C.EmitReport(report); |
| } |
| |
| return UndefinedVal(); |
| } |
| |
| // If it's not a region and not a label, give up. |
| return UnknownVal(); |
| } |
| |
| // If we have a region, strip casts from it and see if we can figure out |
| // its length. For anything we can't figure out, just return UnknownVal. |
| MR = MR->StripCasts(); |
| |
| switch (MR->getKind()) { |
| case MemRegion::StringRegionKind: { |
| // Modifying the contents of string regions is undefined [C99 6.4.5p6], |
| // so we can assume that the byte length is the correct C string length. |
| ValueManager &ValMgr = C.getValueManager(); |
| QualType SizeTy = ValMgr.getContext().getSizeType(); |
| const StringLiteral *Str = cast<StringRegion>(MR)->getStringLiteral(); |
| return ValMgr.makeIntVal(Str->getByteLength(), SizeTy); |
| } |
| case MemRegion::SymbolicRegionKind: |
| case MemRegion::AllocaRegionKind: |
| case MemRegion::VarRegionKind: |
| case MemRegion::FieldRegionKind: |
| case MemRegion::ObjCIvarRegionKind: |
| return GetCStringLengthForRegion(C, state, Ex, MR); |
| case MemRegion::CompoundLiteralRegionKind: |
| // FIXME: Can we track this? Is it necessary? |
| return UnknownVal(); |
| case MemRegion::ElementRegionKind: |
| // FIXME: How can we handle this? It's not good enough to subtract the |
| // offset from the base string length; consider "123\x00567" and &a[5]. |
| return UnknownVal(); |
| default: |
| // Other regions (mostly non-data) can't have a reliable C string length. |
| // In this case, an error is emitted and UndefinedVal is returned. |
| // The caller should always be prepared to handle this case. |
| if (ExplodedNode *N = C.GenerateNode(state)) { |
| if (!BT_NotCString) |
| BT_NotCString = new BuiltinBug("API", |
| "Argument is not a null-terminated string."); |
| |
| llvm::SmallString<120> buf; |
| llvm::raw_svector_ostream os(buf); |
| |
| os << "Argument to byte string function is "; |
| |
| if (SummarizeRegion(os, C.getASTContext(), MR)) |
| os << ", which is not a null-terminated string"; |
| else |
| os << "not a null-terminated string"; |
| |
| // Generate a report for this bug. |
| EnhancedBugReport *report = new EnhancedBugReport(*BT_NotCString, |
| os.str(), N); |
| |
| report->addRange(Ex->getSourceRange()); |
| C.EmitReport(report); |
| } |
| |
| return UndefinedVal(); |
| } |
| } |
| |
| const GRState *CStringChecker::InvalidateBuffer(CheckerContext &C, |
| const GRState *state, |
| const Expr *E, SVal V) { |
| Loc *L = dyn_cast<Loc>(&V); |
| if (!L) |
| return state; |
| |
| // FIXME: This is a simplified version of what's in CFRefCount.cpp -- it makes |
| // some assumptions about the value that CFRefCount can't. Even so, it should |
| // probably be refactored. |
| if (loc::MemRegionVal* MR = dyn_cast<loc::MemRegionVal>(L)) { |
| const MemRegion *R = MR->getRegion()->StripCasts(); |
| |
| // Are we dealing with an ElementRegion? If so, we should be invalidating |
| // the super-region. |
| if (const ElementRegion *ER = dyn_cast<ElementRegion>(R)) { |
| R = ER->getSuperRegion(); |
| // FIXME: What about layers of ElementRegions? |
| } |
| |
| // Invalidate this region. |
| unsigned Count = C.getNodeBuilder().getCurrentBlockCount(); |
| return state->InvalidateRegion(R, E, Count, NULL); |
| } |
| |
| // If we have a non-region value by chance, just remove the binding. |
| // FIXME: is this necessary or correct? This handles the non-Region |
| // cases. Is it ever valid to store to these? |
| return state->unbindLoc(*L); |
| } |
| |
| bool CStringChecker::SummarizeRegion(llvm::raw_ostream& os, ASTContext& Ctx, |
| const MemRegion *MR) { |
| const TypedRegion *TR = dyn_cast<TypedRegion>(MR); |
| if (!TR) |
| return false; |
| |
| switch (TR->getKind()) { |
| case MemRegion::FunctionTextRegionKind: { |
| const FunctionDecl *FD = cast<FunctionTextRegion>(TR)->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: |
| os << "a block"; |
| return true; |
| case MemRegion::CXXThisRegionKind: |
| case MemRegion::CXXObjectRegionKind: |
| os << "a C++ object of type " << TR->getValueType().getAsString(); |
| return true; |
| case MemRegion::VarRegionKind: |
| os << "a variable of type" << TR->getValueType().getAsString(); |
| return true; |
| case MemRegion::FieldRegionKind: |
| os << "a field of type " << TR->getValueType().getAsString(); |
| return true; |
| case MemRegion::ObjCIvarRegionKind: |
| os << "an instance variable of type " << TR->getValueType().getAsString(); |
| return true; |
| default: |
| return false; |
| } |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Evaluation of individual function calls. |
| //===----------------------------------------------------------------------===// |
| |
| void CStringChecker::EvalCopyCommon(CheckerContext &C, const GRState *state, |
| const Expr *Size, const Expr *Dest, |
| const Expr *Source, bool Restricted) { |
| // See if the size argument is zero. |
| SVal SizeVal = state->getSVal(Size); |
| QualType SizeTy = Size->getType(); |
| |
| const GRState *StZeroSize, *StNonZeroSize; |
| llvm::tie(StZeroSize, StNonZeroSize) = AssumeZero(C, state, SizeVal, SizeTy); |
| |
| // If the size is zero, there won't be any actual memory access. |
| if (StZeroSize) |
| C.addTransition(StZeroSize); |
| |
| // If the size can be nonzero, we have to check the other arguments. |
| if (StNonZeroSize) { |
| state = StNonZeroSize; |
| state = CheckBufferAccess(C, state, Size, Dest, Source, |
| /* FirstIsDst = */ true); |
| if (Restricted) |
| state = CheckOverlap(C, state, Size, Dest, Source); |
| |
| if (state) { |
| // Invalidate the destination. |
| // FIXME: Even if we can't perfectly model the copy, we should see if we |
| // can use LazyCompoundVals to copy the source values into the destination. |
| // This would probably remove any existing bindings past the end of the |
| // copied region, but that's still an improvement over blank invalidation. |
| state = InvalidateBuffer(C, state, Dest, state->getSVal(Dest)); |
| C.addTransition(state); |
| } |
| } |
| } |
| |
| |
| void CStringChecker::EvalMemcpy(CheckerContext &C, const CallExpr *CE) { |
| // void *memcpy(void *restrict dst, const void *restrict src, size_t n); |
| // The return value is the address of the destination buffer. |
| const Expr *Dest = CE->getArg(0); |
| const GRState *state = C.getState(); |
| state = state->BindExpr(CE, state->getSVal(Dest)); |
| EvalCopyCommon(C, state, CE->getArg(2), Dest, CE->getArg(1), true); |
| } |
| |
| void CStringChecker::EvalMemmove(CheckerContext &C, const CallExpr *CE) { |
| // void *memmove(void *dst, const void *src, size_t n); |
| // The return value is the address of the destination buffer. |
| const Expr *Dest = CE->getArg(0); |
| const GRState *state = C.getState(); |
| state = state->BindExpr(CE, state->getSVal(Dest)); |
| EvalCopyCommon(C, state, CE->getArg(2), Dest, CE->getArg(1)); |
| } |
| |
| void CStringChecker::EvalBcopy(CheckerContext &C, const CallExpr *CE) { |
| // void bcopy(const void *src, void *dst, size_t n); |
| EvalCopyCommon(C, C.getState(), CE->getArg(2), CE->getArg(1), CE->getArg(0)); |
| } |
| |
| void CStringChecker::EvalMemcmp(CheckerContext &C, const CallExpr *CE) { |
| // int memcmp(const void *s1, const void *s2, size_t n); |
| const Expr *Left = CE->getArg(0); |
| const Expr *Right = CE->getArg(1); |
| const Expr *Size = CE->getArg(2); |
| |
| const GRState *state = C.getState(); |
| ValueManager &ValMgr = C.getValueManager(); |
| SValuator &SV = ValMgr.getSValuator(); |
| |
| // See if the size argument is zero. |
| SVal SizeVal = state->getSVal(Size); |
| QualType SizeTy = Size->getType(); |
| |
| const GRState *StZeroSize, *StNonZeroSize; |
| llvm::tie(StZeroSize, StNonZeroSize) = AssumeZero(C, state, SizeVal, SizeTy); |
| |
| // If the size can be zero, the result will be 0 in that case, and we don't |
| // have to check either of the buffers. |
| if (StZeroSize) { |
| state = StZeroSize; |
| state = state->BindExpr(CE, ValMgr.makeZeroVal(CE->getType())); |
| C.addTransition(state); |
| } |
| |
| // If the size can be nonzero, we have to check the other arguments. |
| if (StNonZeroSize) { |
| state = StNonZeroSize; |
| |
| // If we know the two buffers are the same, we know the result is 0. |
| // First, get the two buffers' addresses. Another checker will have already |
| // made sure they're not undefined. |
| DefinedOrUnknownSVal LV = cast<DefinedOrUnknownSVal>(state->getSVal(Left)); |
| DefinedOrUnknownSVal RV = cast<DefinedOrUnknownSVal>(state->getSVal(Right)); |
| |
| // See if they are the same. |
| DefinedOrUnknownSVal SameBuf = SV.EvalEQ(state, LV, RV); |
| const GRState *StSameBuf, *StNotSameBuf; |
| llvm::tie(StSameBuf, StNotSameBuf) = state->Assume(SameBuf); |
| |
| // If the two arguments might be the same buffer, we know the result is zero, |
| // and we only need to check one size. |
| if (StSameBuf) { |
| state = StSameBuf; |
| state = CheckBufferAccess(C, state, Size, Left); |
| if (state) { |
| state = StSameBuf->BindExpr(CE, ValMgr.makeZeroVal(CE->getType())); |
| C.addTransition(state); |
| } |
| } |
| |
| // If the two arguments might be different buffers, we have to check the |
| // size of both of them. |
| if (StNotSameBuf) { |
| state = StNotSameBuf; |
| state = CheckBufferAccess(C, state, Size, Left, Right); |
| if (state) { |
| // The return value is the comparison result, which we don't know. |
| unsigned Count = C.getNodeBuilder().getCurrentBlockCount(); |
| SVal CmpV = ValMgr.getConjuredSymbolVal(NULL, CE, Count); |
| state = state->BindExpr(CE, CmpV); |
| C.addTransition(state); |
| } |
| } |
| } |
| } |
| |
| void CStringChecker::EvalStrlen(CheckerContext &C, const CallExpr *CE) { |
| // size_t strlen(const char *s); |
| const GRState *state = C.getState(); |
| const Expr *Arg = CE->getArg(0); |
| SVal ArgVal = state->getSVal(Arg); |
| |
| // Check that the argument is non-null. |
| state = CheckNonNull(C, state, Arg, ArgVal); |
| |
| if (state) { |
| SVal StrLen = GetCStringLength(C, state, Arg, ArgVal); |
| |
| // If the argument isn't a valid C string, there's no valid state to |
| // transition to. |
| if (StrLen.isUndef()) |
| return; |
| |
| // If GetCStringLength couldn't figure out the length, conjure a return |
| // value, so it can be used in constraints, at least. |
| if (StrLen.isUnknown()) { |
| ValueManager &ValMgr = C.getValueManager(); |
| unsigned Count = C.getNodeBuilder().getCurrentBlockCount(); |
| StrLen = ValMgr.getConjuredSymbolVal(NULL, CE, Count); |
| } |
| |
| // Bind the return value. |
| state = state->BindExpr(CE, StrLen); |
| C.addTransition(state); |
| } |
| } |
| |
| void CStringChecker::EvalStrcpy(CheckerContext &C, const CallExpr *CE) { |
| // char *strcpy(char *restrict dst, const char *restrict src); |
| EvalStrcpyCommon(C, CE, /* ReturnEnd = */ false); |
| } |
| |
| void CStringChecker::EvalStpcpy(CheckerContext &C, const CallExpr *CE) { |
| // char *stpcpy(char *restrict dst, const char *restrict src); |
| EvalStrcpyCommon(C, CE, /* ReturnEnd = */ true); |
| } |
| |
| void CStringChecker::EvalStrcpyCommon(CheckerContext &C, const CallExpr *CE, |
| bool ReturnEnd) { |
| const GRState *state = C.getState(); |
| |
| // Check that the destination is non-null |
| const Expr *Dst = CE->getArg(0); |
| SVal DstVal = state->getSVal(Dst); |
| |
| state = CheckNonNull(C, state, Dst, DstVal); |
| if (!state) |
| return; |
| |
| // Check that the source is non-null. |
| const Expr *Src = CE->getArg(1); |
| SVal SrcVal = state->getSVal(Src); |
| |
| state = CheckNonNull(C, state, Src, SrcVal); |
| if (!state) |
| return; |
| |
| // Get the string length of the source. |
| SVal StrLen = GetCStringLength(C, state, Src, SrcVal); |
| |
| // If the source isn't a valid C string, give up. |
| if (StrLen.isUndef()) |
| return; |
| |
| SVal Result = (ReturnEnd ? UnknownVal() : DstVal); |
| |
| // If the destination is a MemRegion, try to check for a buffer overflow and |
| // record the new string length. |
| if (loc::MemRegionVal *DstRegVal = dyn_cast<loc::MemRegionVal>(&DstVal)) { |
| // If the length is known, we can check for an overflow. |
| if (NonLoc *KnownStrLen = dyn_cast<NonLoc>(&StrLen)) { |
| SValuator &SV = C.getSValuator(); |
| |
| SVal LastElement = SV.EvalBinOpLN(state, BO_Add, |
| *DstRegVal, *KnownStrLen, |
| Dst->getType()); |
| |
| state = CheckLocation(C, state, Dst, LastElement, /* IsDst = */ true); |
| if (!state) |
| return; |
| |
| // If this is a stpcpy-style copy, the last element is the return value. |
| if (ReturnEnd) |
| Result = LastElement; |
| } |
| |
| // Invalidate the destination. This must happen before we set the C string |
| // length because invalidation will clear the length. |
| // FIXME: Even if we can't perfectly model the copy, we should see if we |
| // can use LazyCompoundVals to copy the source values into the destination. |
| // This would probably remove any existing bindings past the end of the |
| // string, but that's still an improvement over blank invalidation. |
| state = InvalidateBuffer(C, state, Dst, *DstRegVal); |
| |
| // Set the C string length of the destination. |
| state = SetCStringLength(state, DstRegVal->getRegion(), StrLen); |
| } |
| |
| // If this is a stpcpy-style copy, but we were unable to check for a buffer |
| // overflow, we still need a result. Conjure a return value. |
| if (ReturnEnd && Result.isUnknown()) { |
| ValueManager &ValMgr = C.getValueManager(); |
| unsigned Count = C.getNodeBuilder().getCurrentBlockCount(); |
| StrLen = ValMgr.getConjuredSymbolVal(NULL, CE, Count); |
| } |
| |
| // Set the return value. |
| state = state->BindExpr(CE, Result); |
| C.addTransition(state); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // The driver method, and other Checker callbacks. |
| //===----------------------------------------------------------------------===// |
| |
| bool CStringChecker::EvalCallExpr(CheckerContext &C, const CallExpr *CE) { |
| // Get the callee. All the functions we care about are C functions |
| // with simple identifiers. |
| const GRState *state = C.getState(); |
| const Expr *Callee = CE->getCallee(); |
| const FunctionDecl *FD = state->getSVal(Callee).getAsFunctionDecl(); |
| |
| if (!FD) |
| return false; |
| |
| // Get the name of the callee. If it's a builtin, strip off the prefix. |
| IdentifierInfo *II = FD->getIdentifier(); |
| if (!II) // if no identifier, not a simple C function |
| return false; |
| llvm::StringRef Name = II->getName(); |
| if (Name.startswith("__builtin_")) |
| Name = Name.substr(10); |
| |
| FnCheck EvalFunction = llvm::StringSwitch<FnCheck>(Name) |
| .Cases("memcpy", "__memcpy_chk", &CStringChecker::EvalMemcpy) |
| .Cases("memcmp", "bcmp", &CStringChecker::EvalMemcmp) |
| .Cases("memmove", "__memmove_chk", &CStringChecker::EvalMemmove) |
| .Cases("strcpy", "__strcpy_chk", &CStringChecker::EvalStrcpy) |
| .Cases("stpcpy", "__stpcpy_chk", &CStringChecker::EvalStpcpy) |
| .Case("strlen", &CStringChecker::EvalStrlen) |
| .Case("bcopy", &CStringChecker::EvalBcopy) |
| .Default(NULL); |
| |
| // If the callee isn't a string function, let another checker handle it. |
| if (!EvalFunction) |
| return false; |
| |
| // Check and evaluate the call. |
| (this->*EvalFunction)(C, CE); |
| return true; |
| } |
| |
| void CStringChecker::PreVisitDeclStmt(CheckerContext &C, const DeclStmt *DS) { |
| // Record string length for char a[] = "abc"; |
| const GRState *state = C.getState(); |
| |
| for (DeclStmt::const_decl_iterator I = DS->decl_begin(), E = DS->decl_end(); |
| I != E; ++I) { |
| const VarDecl *D = dyn_cast<VarDecl>(*I); |
| if (!D) |
| continue; |
| |
| // FIXME: Handle array fields of structs. |
| if (!D->getType()->isArrayType()) |
| continue; |
| |
| const Expr *Init = D->getInit(); |
| if (!Init) |
| continue; |
| if (!isa<StringLiteral>(Init)) |
| continue; |
| |
| Loc VarLoc = state->getLValue(D, C.getPredecessor()->getLocationContext()); |
| const MemRegion *MR = VarLoc.getAsRegion(); |
| if (!MR) |
| continue; |
| |
| SVal StrVal = state->getSVal(Init); |
| assert(StrVal.isValid() && "Initializer string is unknown or undefined"); |
| DefinedOrUnknownSVal StrLen |
| = cast<DefinedOrUnknownSVal>(GetCStringLength(C, state, Init, StrVal)); |
| |
| state = state->set<CStringLength>(MR, StrLen); |
| } |
| |
| C.addTransition(state); |
| } |
| |
| bool CStringChecker::WantsRegionChangeUpdate(const GRState *state) { |
| CStringLength::EntryMap Entries = state->get<CStringLength>(); |
| return !Entries.isEmpty(); |
| } |
| |
| const GRState *CStringChecker::EvalRegionChanges(const GRState *state, |
| const MemRegion * const *Begin, |
| const MemRegion * const *End, |
| bool *) { |
| CStringLength::EntryMap Entries = state->get<CStringLength>(); |
| if (Entries.isEmpty()) |
| return state; |
| |
| llvm::SmallPtrSet<const MemRegion *, 8> Invalidated; |
| llvm::SmallPtrSet<const MemRegion *, 32> SuperRegions; |
| |
| // First build sets for the changed regions and their super-regions. |
| for ( ; Begin != End; ++Begin) { |
| const MemRegion *MR = *Begin; |
| Invalidated.insert(MR); |
| |
| SuperRegions.insert(MR); |
| while (const SubRegion *SR = dyn_cast<SubRegion>(MR)) { |
| MR = SR->getSuperRegion(); |
| SuperRegions.insert(MR); |
| } |
| } |
| |
| CStringLength::EntryMap::Factory &F = state->get_context<CStringLength>(); |
| |
| // Then loop over the entries in the current state. |
| for (CStringLength::EntryMap::iterator I = Entries.begin(), |
| E = Entries.end(); I != E; ++I) { |
| const MemRegion *MR = I.getKey(); |
| |
| // Is this entry for a super-region of a changed region? |
| if (SuperRegions.count(MR)) { |
| Entries = F.remove(Entries, MR); |
| continue; |
| } |
| |
| // Is this entry for a sub-region of a changed region? |
| const MemRegion *Super = MR; |
| while (const SubRegion *SR = dyn_cast<SubRegion>(Super)) { |
| Super = SR->getSuperRegion(); |
| if (Invalidated.count(Super)) { |
| Entries = F.remove(Entries, MR); |
| break; |
| } |
| } |
| } |
| |
| return state->set<CStringLength>(Entries); |
| } |
| |
| void CStringChecker::MarkLiveSymbols(const GRState *state, SymbolReaper &SR) { |
| // Mark all symbols in our string length map as valid. |
| CStringLength::EntryMap Entries = state->get<CStringLength>(); |
| |
| for (CStringLength::EntryMap::iterator I = Entries.begin(), E = Entries.end(); |
| I != E; ++I) { |
| SVal Len = I.getData(); |
| if (SymbolRef Sym = Len.getAsSymbol()) |
| SR.markInUse(Sym); |
| } |
| } |
| |
| void CStringChecker::EvalDeadSymbols(CheckerContext &C, SymbolReaper &SR) { |
| if (!SR.hasDeadSymbols()) |
| return; |
| |
| const GRState *state = C.getState(); |
| CStringLength::EntryMap Entries = state->get<CStringLength>(); |
| if (Entries.isEmpty()) |
| return; |
| |
| CStringLength::EntryMap::Factory &F = state->get_context<CStringLength>(); |
| for (CStringLength::EntryMap::iterator I = Entries.begin(), E = Entries.end(); |
| I != E; ++I) { |
| SVal Len = I.getData(); |
| if (SymbolRef Sym = Len.getAsSymbol()) { |
| if (SR.isDead(Sym)) |
| Entries = F.remove(Entries, I.getKey()); |
| } |
| } |
| |
| state = state->set<CStringLength>(Entries); |
| C.GenerateNode(state); |
| } |