1 //= CStringChecker.cpp - Checks calls to C string functions --------*- C++ -*-//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This defines CStringChecker, which is an assortment of checks on calls
11 // to functions in <string.h>.
13 //===----------------------------------------------------------------------===//
15 #include "ClangSACheckers.h"
16 #include "InterCheckerAPI.h"
17 #include "clang/Basic/CharInfo.h"
18 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
19 #include "clang/StaticAnalyzer/Core/Checker.h"
20 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
21 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
22 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
23 #include "llvm/ADT/STLExtras.h"
24 #include "llvm/ADT/SmallString.h"
25 #include "llvm/ADT/StringSwitch.h"
26 #include "llvm/Support/raw_ostream.h"
28 using namespace clang;
32 class CStringChecker : public Checker< eval::Call,
33 check::PreStmt<DeclStmt>,
38 mutable std::unique_ptr<BugType> BT_Null, BT_Bounds, BT_Overlap,
39 BT_NotCString, BT_AdditionOverflow;
41 mutable const char *CurrentFunctionDescription;
44 /// The filter is used to filter out the diagnostics which are not enabled by
46 struct CStringChecksFilter {
47 DefaultBool CheckCStringNullArg;
48 DefaultBool CheckCStringOutOfBounds;
49 DefaultBool CheckCStringBufferOverlap;
50 DefaultBool CheckCStringNotNullTerm;
52 CheckName CheckNameCStringNullArg;
53 CheckName CheckNameCStringOutOfBounds;
54 CheckName CheckNameCStringBufferOverlap;
55 CheckName CheckNameCStringNotNullTerm;
58 CStringChecksFilter Filter;
60 static void *getTag() { static int tag; return &tag; }
62 bool evalCall(const CallExpr *CE, CheckerContext &C) const;
63 void checkPreStmt(const DeclStmt *DS, CheckerContext &C) const;
64 void checkLiveSymbols(ProgramStateRef state, SymbolReaper &SR) const;
65 void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const;
66 bool wantsRegionChangeUpdate(ProgramStateRef state) const;
69 checkRegionChanges(ProgramStateRef state,
70 const InvalidatedSymbols *,
71 ArrayRef<const MemRegion *> ExplicitRegions,
72 ArrayRef<const MemRegion *> Regions,
73 const CallEvent *Call) const;
75 typedef void (CStringChecker::*FnCheck)(CheckerContext &,
76 const CallExpr *) const;
78 void evalMemcpy(CheckerContext &C, const CallExpr *CE) const;
79 void evalMempcpy(CheckerContext &C, const CallExpr *CE) const;
80 void evalMemmove(CheckerContext &C, const CallExpr *CE) const;
81 void evalBcopy(CheckerContext &C, const CallExpr *CE) const;
82 void evalCopyCommon(CheckerContext &C, const CallExpr *CE,
83 ProgramStateRef state,
87 bool Restricted = false,
88 bool IsMempcpy = false) const;
90 void evalMemcmp(CheckerContext &C, const CallExpr *CE) const;
92 void evalstrLength(CheckerContext &C, const CallExpr *CE) const;
93 void evalstrnLength(CheckerContext &C, const CallExpr *CE) const;
94 void evalstrLengthCommon(CheckerContext &C,
96 bool IsStrnlen = false) const;
98 void evalStrcpy(CheckerContext &C, const CallExpr *CE) const;
99 void evalStrncpy(CheckerContext &C, const CallExpr *CE) const;
100 void evalStpcpy(CheckerContext &C, const CallExpr *CE) const;
101 void evalStrcpyCommon(CheckerContext &C,
105 bool isAppending) const;
107 void evalStrcat(CheckerContext &C, const CallExpr *CE) const;
108 void evalStrncat(CheckerContext &C, const CallExpr *CE) const;
110 void evalStrcmp(CheckerContext &C, const CallExpr *CE) const;
111 void evalStrncmp(CheckerContext &C, const CallExpr *CE) const;
112 void evalStrcasecmp(CheckerContext &C, const CallExpr *CE) const;
113 void evalStrncasecmp(CheckerContext &C, const CallExpr *CE) const;
114 void evalStrcmpCommon(CheckerContext &C,
116 bool isBounded = false,
117 bool ignoreCase = false) const;
119 void evalStrsep(CheckerContext &C, const CallExpr *CE) const;
122 std::pair<ProgramStateRef , ProgramStateRef >
123 static assumeZero(CheckerContext &C,
124 ProgramStateRef state, SVal V, QualType Ty);
126 static ProgramStateRef setCStringLength(ProgramStateRef state,
129 static SVal getCStringLengthForRegion(CheckerContext &C,
130 ProgramStateRef &state,
134 SVal getCStringLength(CheckerContext &C,
135 ProgramStateRef &state,
138 bool hypothetical = false) const;
140 const StringLiteral *getCStringLiteral(CheckerContext &C,
141 ProgramStateRef &state,
145 static ProgramStateRef InvalidateBuffer(CheckerContext &C,
146 ProgramStateRef state,
147 const Expr *Ex, SVal V,
148 bool IsSourceBuffer);
150 static bool SummarizeRegion(raw_ostream &os, ASTContext &Ctx,
151 const MemRegion *MR);
154 ProgramStateRef checkNonNull(CheckerContext &C,
155 ProgramStateRef state,
158 ProgramStateRef CheckLocation(CheckerContext &C,
159 ProgramStateRef state,
162 const char *message = nullptr) const;
163 ProgramStateRef CheckBufferAccess(CheckerContext &C,
164 ProgramStateRef state,
166 const Expr *FirstBuf,
167 const Expr *SecondBuf,
168 const char *firstMessage = nullptr,
169 const char *secondMessage = nullptr,
170 bool WarnAboutSize = false) const;
172 ProgramStateRef CheckBufferAccess(CheckerContext &C,
173 ProgramStateRef state,
176 const char *message = nullptr,
177 bool WarnAboutSize = false) const {
178 // This is a convenience override.
179 return CheckBufferAccess(C, state, Size, Buf, nullptr, message, nullptr,
182 ProgramStateRef CheckOverlap(CheckerContext &C,
183 ProgramStateRef state,
186 const Expr *Second) const;
187 void emitOverlapBug(CheckerContext &C,
188 ProgramStateRef state,
190 const Stmt *Second) const;
192 ProgramStateRef checkAdditionOverflow(CheckerContext &C,
193 ProgramStateRef state,
198 } //end anonymous namespace
200 REGISTER_MAP_WITH_PROGRAMSTATE(CStringLength, const MemRegion *, SVal)
202 //===----------------------------------------------------------------------===//
203 // Individual checks and utility methods.
204 //===----------------------------------------------------------------------===//
206 std::pair<ProgramStateRef , ProgramStateRef >
207 CStringChecker::assumeZero(CheckerContext &C, ProgramStateRef state, SVal V,
209 Optional<DefinedSVal> val = V.getAs<DefinedSVal>();
211 return std::pair<ProgramStateRef , ProgramStateRef >(state, state);
213 SValBuilder &svalBuilder = C.getSValBuilder();
214 DefinedOrUnknownSVal zero = svalBuilder.makeZeroVal(Ty);
215 return state->assume(svalBuilder.evalEQ(state, *val, zero));
218 ProgramStateRef CStringChecker::checkNonNull(CheckerContext &C,
219 ProgramStateRef state,
220 const Expr *S, SVal l) const {
221 // If a previous check has failed, propagate the failure.
225 ProgramStateRef stateNull, stateNonNull;
226 std::tie(stateNull, stateNonNull) = assumeZero(C, state, l, S->getType());
228 if (stateNull && !stateNonNull) {
229 if (!Filter.CheckCStringNullArg)
232 ExplodedNode *N = C.generateSink(stateNull);
237 BT_Null.reset(new BuiltinBug(
238 Filter.CheckNameCStringNullArg, categories::UnixAPI,
239 "Null pointer argument in call to byte string function"));
242 llvm::raw_svector_ostream os(buf);
243 assert(CurrentFunctionDescription);
244 os << "Null pointer argument in call to " << CurrentFunctionDescription;
246 // Generate a report for this bug.
247 BuiltinBug *BT = static_cast<BuiltinBug*>(BT_Null.get());
248 auto report = llvm::make_unique<BugReport>(*BT, os.str(), N);
250 report->addRange(S->getSourceRange());
251 bugreporter::trackNullOrUndefValue(N, S, *report);
252 C.emitReport(std::move(report));
256 // From here on, assume that the value is non-null.
257 assert(stateNonNull);
261 // FIXME: This was originally copied from ArrayBoundChecker.cpp. Refactor?
262 ProgramStateRef CStringChecker::CheckLocation(CheckerContext &C,
263 ProgramStateRef state,
264 const Expr *S, SVal l,
265 const char *warningMsg) const {
266 // If a previous check has failed, propagate the failure.
270 // Check for out of bound array element access.
271 const MemRegion *R = l.getAsRegion();
275 const ElementRegion *ER = dyn_cast<ElementRegion>(R);
279 assert(ER->getValueType() == C.getASTContext().CharTy &&
280 "CheckLocation should only be called with char* ElementRegions");
282 // Get the size of the array.
283 const SubRegion *superReg = cast<SubRegion>(ER->getSuperRegion());
284 SValBuilder &svalBuilder = C.getSValBuilder();
286 svalBuilder.convertToArrayIndex(superReg->getExtent(svalBuilder));
287 DefinedOrUnknownSVal Size = Extent.castAs<DefinedOrUnknownSVal>();
289 // Get the index of the accessed element.
290 DefinedOrUnknownSVal Idx = ER->getIndex().castAs<DefinedOrUnknownSVal>();
292 ProgramStateRef StInBound = state->assumeInBound(Idx, Size, true);
293 ProgramStateRef StOutBound = state->assumeInBound(Idx, Size, false);
294 if (StOutBound && !StInBound) {
295 ExplodedNode *N = C.generateSink(StOutBound);
300 BT_Bounds.reset(new BuiltinBug(
301 Filter.CheckNameCStringOutOfBounds, "Out-of-bound array access",
302 "Byte string function accesses out-of-bound array element"));
304 BuiltinBug *BT = static_cast<BuiltinBug*>(BT_Bounds.get());
306 // Generate a report for this bug.
307 std::unique_ptr<BugReport> report;
309 report = llvm::make_unique<BugReport>(*BT, warningMsg, N);
311 assert(CurrentFunctionDescription);
312 assert(CurrentFunctionDescription[0] != '\0');
315 llvm::raw_svector_ostream os(buf);
316 os << toUppercase(CurrentFunctionDescription[0])
317 << &CurrentFunctionDescription[1]
318 << " accesses out-of-bound array element";
319 report = llvm::make_unique<BugReport>(*BT, os.str(), N);
322 // FIXME: It would be nice to eventually make this diagnostic more clear,
323 // e.g., by referencing the original declaration or by saying *why* this
324 // reference is outside the range.
326 report->addRange(S->getSourceRange());
327 C.emitReport(std::move(report));
331 // Array bound check succeeded. From this point forward the array bound
332 // should always succeed.
336 ProgramStateRef CStringChecker::CheckBufferAccess(CheckerContext &C,
337 ProgramStateRef state,
339 const Expr *FirstBuf,
340 const Expr *SecondBuf,
341 const char *firstMessage,
342 const char *secondMessage,
343 bool WarnAboutSize) const {
344 // If a previous check has failed, propagate the failure.
348 SValBuilder &svalBuilder = C.getSValBuilder();
349 ASTContext &Ctx = svalBuilder.getContext();
350 const LocationContext *LCtx = C.getLocationContext();
352 QualType sizeTy = Size->getType();
353 QualType PtrTy = Ctx.getPointerType(Ctx.CharTy);
355 // Check that the first buffer is non-null.
356 SVal BufVal = state->getSVal(FirstBuf, LCtx);
357 state = checkNonNull(C, state, FirstBuf, BufVal);
361 // If out-of-bounds checking is turned off, skip the rest.
362 if (!Filter.CheckCStringOutOfBounds)
365 // Get the access length and make sure it is known.
366 // FIXME: This assumes the caller has already checked that the access length
367 // is positive. And that it's unsigned.
368 SVal LengthVal = state->getSVal(Size, LCtx);
369 Optional<NonLoc> Length = LengthVal.getAs<NonLoc>();
373 // Compute the offset of the last element to be accessed: size-1.
374 NonLoc One = svalBuilder.makeIntVal(1, sizeTy).castAs<NonLoc>();
375 NonLoc LastOffset = svalBuilder
376 .evalBinOpNN(state, BO_Sub, *Length, One, sizeTy).castAs<NonLoc>();
378 // Check that the first buffer is sufficiently long.
379 SVal BufStart = svalBuilder.evalCast(BufVal, PtrTy, FirstBuf->getType());
380 if (Optional<Loc> BufLoc = BufStart.getAs<Loc>()) {
381 const Expr *warningExpr = (WarnAboutSize ? Size : FirstBuf);
383 SVal BufEnd = svalBuilder.evalBinOpLN(state, BO_Add, *BufLoc,
385 state = CheckLocation(C, state, warningExpr, BufEnd, firstMessage);
387 // If the buffer isn't large enough, abort.
392 // If there's a second buffer, check it as well.
394 BufVal = state->getSVal(SecondBuf, LCtx);
395 state = checkNonNull(C, state, SecondBuf, BufVal);
399 BufStart = svalBuilder.evalCast(BufVal, PtrTy, SecondBuf->getType());
400 if (Optional<Loc> BufLoc = BufStart.getAs<Loc>()) {
401 const Expr *warningExpr = (WarnAboutSize ? Size : SecondBuf);
403 SVal BufEnd = svalBuilder.evalBinOpLN(state, BO_Add, *BufLoc,
405 state = CheckLocation(C, state, warningExpr, BufEnd, secondMessage);
409 // Large enough or not, return this state!
413 ProgramStateRef CStringChecker::CheckOverlap(CheckerContext &C,
414 ProgramStateRef state,
417 const Expr *Second) const {
418 if (!Filter.CheckCStringBufferOverlap)
421 // Do a simple check for overlap: if the two arguments are from the same
422 // buffer, see if the end of the first is greater than the start of the second
425 // If a previous check has failed, propagate the failure.
429 ProgramStateRef stateTrue, stateFalse;
431 // Get the buffer values and make sure they're known locations.
432 const LocationContext *LCtx = C.getLocationContext();
433 SVal firstVal = state->getSVal(First, LCtx);
434 SVal secondVal = state->getSVal(Second, LCtx);
436 Optional<Loc> firstLoc = firstVal.getAs<Loc>();
440 Optional<Loc> secondLoc = secondVal.getAs<Loc>();
444 // Are the two values the same?
445 SValBuilder &svalBuilder = C.getSValBuilder();
446 std::tie(stateTrue, stateFalse) =
447 state->assume(svalBuilder.evalEQ(state, *firstLoc, *secondLoc));
449 if (stateTrue && !stateFalse) {
450 // If the values are known to be equal, that's automatically an overlap.
451 emitOverlapBug(C, stateTrue, First, Second);
455 // assume the two expressions are not equal.
459 // Which value comes first?
460 QualType cmpTy = svalBuilder.getConditionType();
461 SVal reverse = svalBuilder.evalBinOpLL(state, BO_GT,
462 *firstLoc, *secondLoc, cmpTy);
463 Optional<DefinedOrUnknownSVal> reverseTest =
464 reverse.getAs<DefinedOrUnknownSVal>();
468 std::tie(stateTrue, stateFalse) = state->assume(*reverseTest);
471 // If we don't know which one comes first, we can't perform this test.
474 // Switch the values so that firstVal is before secondVal.
475 std::swap(firstLoc, secondLoc);
477 // Switch the Exprs as well, so that they still correspond.
478 std::swap(First, Second);
482 // Get the length, and make sure it too is known.
483 SVal LengthVal = state->getSVal(Size, LCtx);
484 Optional<NonLoc> Length = LengthVal.getAs<NonLoc>();
488 // Convert the first buffer's start address to char*.
489 // Bail out if the cast fails.
490 ASTContext &Ctx = svalBuilder.getContext();
491 QualType CharPtrTy = Ctx.getPointerType(Ctx.CharTy);
492 SVal FirstStart = svalBuilder.evalCast(*firstLoc, CharPtrTy,
494 Optional<Loc> FirstStartLoc = FirstStart.getAs<Loc>();
498 // Compute the end of the first buffer. Bail out if THAT fails.
499 SVal FirstEnd = svalBuilder.evalBinOpLN(state, BO_Add,
500 *FirstStartLoc, *Length, CharPtrTy);
501 Optional<Loc> FirstEndLoc = FirstEnd.getAs<Loc>();
505 // Is the end of the first buffer past the start of the second buffer?
506 SVal Overlap = svalBuilder.evalBinOpLL(state, BO_GT,
507 *FirstEndLoc, *secondLoc, cmpTy);
508 Optional<DefinedOrUnknownSVal> OverlapTest =
509 Overlap.getAs<DefinedOrUnknownSVal>();
513 std::tie(stateTrue, stateFalse) = state->assume(*OverlapTest);
515 if (stateTrue && !stateFalse) {
517 emitOverlapBug(C, stateTrue, First, Second);
521 // assume the two expressions don't overlap.
526 void CStringChecker::emitOverlapBug(CheckerContext &C, ProgramStateRef state,
527 const Stmt *First, const Stmt *Second) const {
528 ExplodedNode *N = C.generateSink(state);
533 BT_Overlap.reset(new BugType(Filter.CheckNameCStringBufferOverlap,
534 categories::UnixAPI, "Improper arguments"));
536 // Generate a report for this bug.
537 auto report = llvm::make_unique<BugReport>(
538 *BT_Overlap, "Arguments must not be overlapping buffers", N);
539 report->addRange(First->getSourceRange());
540 report->addRange(Second->getSourceRange());
542 C.emitReport(std::move(report));
545 ProgramStateRef CStringChecker::checkAdditionOverflow(CheckerContext &C,
546 ProgramStateRef state,
548 NonLoc right) const {
549 // If out-of-bounds checking is turned off, skip the rest.
550 if (!Filter.CheckCStringOutOfBounds)
553 // If a previous check has failed, propagate the failure.
557 SValBuilder &svalBuilder = C.getSValBuilder();
558 BasicValueFactory &BVF = svalBuilder.getBasicValueFactory();
560 QualType sizeTy = svalBuilder.getContext().getSizeType();
561 const llvm::APSInt &maxValInt = BVF.getMaxValue(sizeTy);
562 NonLoc maxVal = svalBuilder.makeIntVal(maxValInt);
565 if (right.getAs<nonloc::ConcreteInt>()) {
566 maxMinusRight = svalBuilder.evalBinOpNN(state, BO_Sub, maxVal, right,
569 // Try switching the operands. (The order of these two assignments is
571 maxMinusRight = svalBuilder.evalBinOpNN(state, BO_Sub, maxVal, left,
576 if (Optional<NonLoc> maxMinusRightNL = maxMinusRight.getAs<NonLoc>()) {
577 QualType cmpTy = svalBuilder.getConditionType();
578 // If left > max - right, we have an overflow.
579 SVal willOverflow = svalBuilder.evalBinOpNN(state, BO_GT, left,
580 *maxMinusRightNL, cmpTy);
582 ProgramStateRef stateOverflow, stateOkay;
583 std::tie(stateOverflow, stateOkay) =
584 state->assume(willOverflow.castAs<DefinedOrUnknownSVal>());
586 if (stateOverflow && !stateOkay) {
587 // We have an overflow. Emit a bug report.
588 ExplodedNode *N = C.generateSink(stateOverflow);
592 if (!BT_AdditionOverflow)
593 BT_AdditionOverflow.reset(
594 new BuiltinBug(Filter.CheckNameCStringOutOfBounds, "API",
595 "Sum of expressions causes overflow"));
597 // This isn't a great error message, but this should never occur in real
598 // code anyway -- you'd have to create a buffer longer than a size_t can
599 // represent, which is sort of a contradiction.
600 const char *warning =
601 "This expression will create a string whose length is too big to "
602 "be represented as a size_t";
604 // Generate a report for this bug.
606 llvm::make_unique<BugReport>(*BT_AdditionOverflow, warning, N));
611 // From now on, assume an overflow didn't occur.
619 ProgramStateRef CStringChecker::setCStringLength(ProgramStateRef state,
622 assert(!strLength.isUndef() && "Attempt to set an undefined string length");
624 MR = MR->StripCasts();
626 switch (MR->getKind()) {
627 case MemRegion::StringRegionKind:
628 // FIXME: This can happen if we strcpy() into a string region. This is
629 // undefined [C99 6.4.5p6], but we should still warn about it.
632 case MemRegion::SymbolicRegionKind:
633 case MemRegion::AllocaRegionKind:
634 case MemRegion::VarRegionKind:
635 case MemRegion::FieldRegionKind:
636 case MemRegion::ObjCIvarRegionKind:
637 // These are the types we can currently track string lengths for.
640 case MemRegion::ElementRegionKind:
641 // FIXME: Handle element regions by upper-bounding the parent region's
646 // Other regions (mostly non-data) can't have a reliable C string length.
647 // For now, just ignore the change.
648 // FIXME: These are rare but not impossible. We should output some kind of
649 // warning for things like strcpy((char[]){'a', 0}, "b");
653 if (strLength.isUnknown())
654 return state->remove<CStringLength>(MR);
656 return state->set<CStringLength>(MR, strLength);
659 SVal CStringChecker::getCStringLengthForRegion(CheckerContext &C,
660 ProgramStateRef &state,
665 // If there's a recorded length, go ahead and return it.
666 const SVal *Recorded = state->get<CStringLength>(MR);
671 // Otherwise, get a new symbol and update the state.
672 SValBuilder &svalBuilder = C.getSValBuilder();
673 QualType sizeTy = svalBuilder.getContext().getSizeType();
674 SVal strLength = svalBuilder.getMetadataSymbolVal(CStringChecker::getTag(),
679 if (Optional<NonLoc> strLn = strLength.getAs<NonLoc>()) {
680 // In case of unbounded calls strlen etc bound the range to SIZE_MAX/4
681 BasicValueFactory &BVF = svalBuilder.getBasicValueFactory();
682 const llvm::APSInt &maxValInt = BVF.getMaxValue(sizeTy);
683 llvm::APSInt fourInt = APSIntType(maxValInt).getValue(4);
684 const llvm::APSInt *maxLengthInt = BVF.evalAPSInt(BO_Div, maxValInt,
686 NonLoc maxLength = svalBuilder.makeIntVal(*maxLengthInt);
687 SVal evalLength = svalBuilder.evalBinOpNN(state, BO_LE, *strLn,
689 state = state->assume(evalLength.castAs<DefinedOrUnknownSVal>(), true);
691 state = state->set<CStringLength>(MR, strLength);
697 SVal CStringChecker::getCStringLength(CheckerContext &C, ProgramStateRef &state,
698 const Expr *Ex, SVal Buf,
699 bool hypothetical) const {
700 const MemRegion *MR = Buf.getAsRegion();
702 // If we can't get a region, see if it's something we /know/ isn't a
703 // C string. In the context of locations, the only time we can issue such
704 // a warning is for labels.
705 if (Optional<loc::GotoLabel> Label = Buf.getAs<loc::GotoLabel>()) {
706 if (!Filter.CheckCStringNotNullTerm)
707 return UndefinedVal();
709 if (ExplodedNode *N = C.addTransition(state)) {
711 BT_NotCString.reset(new BuiltinBug(
712 Filter.CheckNameCStringNotNullTerm, categories::UnixAPI,
713 "Argument is not a null-terminated string."));
715 SmallString<120> buf;
716 llvm::raw_svector_ostream os(buf);
717 assert(CurrentFunctionDescription);
718 os << "Argument to " << CurrentFunctionDescription
719 << " is the address of the label '" << Label->getLabel()->getName()
720 << "', which is not a null-terminated string";
722 // Generate a report for this bug.
723 auto report = llvm::make_unique<BugReport>(*BT_NotCString, os.str(), N);
725 report->addRange(Ex->getSourceRange());
726 C.emitReport(std::move(report));
728 return UndefinedVal();
732 // If it's not a region and not a label, give up.
736 // If we have a region, strip casts from it and see if we can figure out
737 // its length. For anything we can't figure out, just return UnknownVal.
738 MR = MR->StripCasts();
740 switch (MR->getKind()) {
741 case MemRegion::StringRegionKind: {
742 // Modifying the contents of string regions is undefined [C99 6.4.5p6],
743 // so we can assume that the byte length is the correct C string length.
744 SValBuilder &svalBuilder = C.getSValBuilder();
745 QualType sizeTy = svalBuilder.getContext().getSizeType();
746 const StringLiteral *strLit = cast<StringRegion>(MR)->getStringLiteral();
747 return svalBuilder.makeIntVal(strLit->getByteLength(), sizeTy);
749 case MemRegion::SymbolicRegionKind:
750 case MemRegion::AllocaRegionKind:
751 case MemRegion::VarRegionKind:
752 case MemRegion::FieldRegionKind:
753 case MemRegion::ObjCIvarRegionKind:
754 return getCStringLengthForRegion(C, state, Ex, MR, hypothetical);
755 case MemRegion::CompoundLiteralRegionKind:
756 // FIXME: Can we track this? Is it necessary?
758 case MemRegion::ElementRegionKind:
759 // FIXME: How can we handle this? It's not good enough to subtract the
760 // offset from the base string length; consider "123\x00567" and &a[5].
763 // Other regions (mostly non-data) can't have a reliable C string length.
764 // In this case, an error is emitted and UndefinedVal is returned.
765 // The caller should always be prepared to handle this case.
766 if (!Filter.CheckCStringNotNullTerm)
767 return UndefinedVal();
769 if (ExplodedNode *N = C.addTransition(state)) {
771 BT_NotCString.reset(new BuiltinBug(
772 Filter.CheckNameCStringNotNullTerm, categories::UnixAPI,
773 "Argument is not a null-terminated string."));
775 SmallString<120> buf;
776 llvm::raw_svector_ostream os(buf);
778 assert(CurrentFunctionDescription);
779 os << "Argument to " << CurrentFunctionDescription << " is ";
781 if (SummarizeRegion(os, C.getASTContext(), MR))
782 os << ", which is not a null-terminated string";
784 os << "not a null-terminated string";
786 // Generate a report for this bug.
787 auto report = llvm::make_unique<BugReport>(*BT_NotCString, os.str(), N);
789 report->addRange(Ex->getSourceRange());
790 C.emitReport(std::move(report));
793 return UndefinedVal();
797 const StringLiteral *CStringChecker::getCStringLiteral(CheckerContext &C,
798 ProgramStateRef &state, const Expr *expr, SVal val) const {
800 // Get the memory region pointed to by the val.
801 const MemRegion *bufRegion = val.getAsRegion();
805 // Strip casts off the memory region.
806 bufRegion = bufRegion->StripCasts();
808 // Cast the memory region to a string region.
809 const StringRegion *strRegion= dyn_cast<StringRegion>(bufRegion);
813 // Return the actual string in the string region.
814 return strRegion->getStringLiteral();
817 ProgramStateRef CStringChecker::InvalidateBuffer(CheckerContext &C,
818 ProgramStateRef state,
819 const Expr *E, SVal V,
820 bool IsSourceBuffer) {
821 Optional<Loc> L = V.getAs<Loc>();
825 // FIXME: This is a simplified version of what's in CFRefCount.cpp -- it makes
826 // some assumptions about the value that CFRefCount can't. Even so, it should
827 // probably be refactored.
828 if (Optional<loc::MemRegionVal> MR = L->getAs<loc::MemRegionVal>()) {
829 const MemRegion *R = MR->getRegion()->StripCasts();
831 // Are we dealing with an ElementRegion? If so, we should be invalidating
833 if (const ElementRegion *ER = dyn_cast<ElementRegion>(R)) {
834 R = ER->getSuperRegion();
835 // FIXME: What about layers of ElementRegions?
838 // Invalidate this region.
839 const LocationContext *LCtx = C.getPredecessor()->getLocationContext();
841 bool CausesPointerEscape = false;
842 RegionAndSymbolInvalidationTraits ITraits;
843 // Invalidate and escape only indirect regions accessible through the source
845 if (IsSourceBuffer) {
847 RegionAndSymbolInvalidationTraits::TK_PreserveContents);
848 ITraits.setTrait(R, RegionAndSymbolInvalidationTraits::TK_SuppressEscape);
849 CausesPointerEscape = true;
852 return state->invalidateRegions(R, E, C.blockCount(), LCtx,
853 CausesPointerEscape, nullptr, nullptr,
857 // If we have a non-region value by chance, just remove the binding.
858 // FIXME: is this necessary or correct? This handles the non-Region
859 // cases. Is it ever valid to store to these?
860 return state->killBinding(*L);
863 bool CStringChecker::SummarizeRegion(raw_ostream &os, ASTContext &Ctx,
864 const MemRegion *MR) {
865 const TypedValueRegion *TVR = dyn_cast<TypedValueRegion>(MR);
867 switch (MR->getKind()) {
868 case MemRegion::FunctionTextRegionKind: {
869 const NamedDecl *FD = cast<FunctionTextRegion>(MR)->getDecl();
871 os << "the address of the function '" << *FD << '\'';
873 os << "the address of a function";
876 case MemRegion::BlockTextRegionKind:
879 case MemRegion::BlockDataRegionKind:
882 case MemRegion::CXXThisRegionKind:
883 case MemRegion::CXXTempObjectRegionKind:
884 os << "a C++ temp object of type " << TVR->getValueType().getAsString();
886 case MemRegion::VarRegionKind:
887 os << "a variable of type" << TVR->getValueType().getAsString();
889 case MemRegion::FieldRegionKind:
890 os << "a field of type " << TVR->getValueType().getAsString();
892 case MemRegion::ObjCIvarRegionKind:
893 os << "an instance variable of type " << TVR->getValueType().getAsString();
900 //===----------------------------------------------------------------------===//
901 // evaluation of individual function calls.
902 //===----------------------------------------------------------------------===//
904 void CStringChecker::evalCopyCommon(CheckerContext &C,
906 ProgramStateRef state,
907 const Expr *Size, const Expr *Dest,
908 const Expr *Source, bool Restricted,
909 bool IsMempcpy) const {
910 CurrentFunctionDescription = "memory copy function";
912 // See if the size argument is zero.
913 const LocationContext *LCtx = C.getLocationContext();
914 SVal sizeVal = state->getSVal(Size, LCtx);
915 QualType sizeTy = Size->getType();
917 ProgramStateRef stateZeroSize, stateNonZeroSize;
918 std::tie(stateZeroSize, stateNonZeroSize) =
919 assumeZero(C, state, sizeVal, sizeTy);
921 // Get the value of the Dest.
922 SVal destVal = state->getSVal(Dest, LCtx);
924 // If the size is zero, there won't be any actual memory access, so
925 // just bind the return value to the destination buffer and return.
926 if (stateZeroSize && !stateNonZeroSize) {
927 stateZeroSize = stateZeroSize->BindExpr(CE, LCtx, destVal);
928 C.addTransition(stateZeroSize);
932 // If the size can be nonzero, we have to check the other arguments.
933 if (stateNonZeroSize) {
934 state = stateNonZeroSize;
936 // Ensure the destination is not null. If it is NULL there will be a
937 // NULL pointer dereference.
938 state = checkNonNull(C, state, Dest, destVal);
942 // Get the value of the Src.
943 SVal srcVal = state->getSVal(Source, LCtx);
945 // Ensure the source is not null. If it is NULL there will be a
946 // NULL pointer dereference.
947 state = checkNonNull(C, state, Source, srcVal);
951 // Ensure the accesses are valid and that the buffers do not overlap.
952 const char * const writeWarning =
953 "Memory copy function overflows destination buffer";
954 state = CheckBufferAccess(C, state, Size, Dest, Source,
955 writeWarning, /* sourceWarning = */ nullptr);
957 state = CheckOverlap(C, state, Size, Dest, Source);
962 // If this is mempcpy, get the byte after the last byte copied and
965 loc::MemRegionVal destRegVal = destVal.castAs<loc::MemRegionVal>();
967 // Get the length to copy.
968 if (Optional<NonLoc> lenValNonLoc = sizeVal.getAs<NonLoc>()) {
969 // Get the byte after the last byte copied.
970 SValBuilder &SvalBuilder = C.getSValBuilder();
971 ASTContext &Ctx = SvalBuilder.getContext();
972 QualType CharPtrTy = Ctx.getPointerType(Ctx.CharTy);
973 loc::MemRegionVal DestRegCharVal = SvalBuilder.evalCast(destRegVal,
974 CharPtrTy, Dest->getType()).castAs<loc::MemRegionVal>();
975 SVal lastElement = C.getSValBuilder().evalBinOpLN(state, BO_Add,
980 // The byte after the last byte copied is the return value.
981 state = state->BindExpr(CE, LCtx, lastElement);
983 // If we don't know how much we copied, we can at least
984 // conjure a return value for later.
985 SVal result = C.getSValBuilder().conjureSymbolVal(nullptr, CE, LCtx,
987 state = state->BindExpr(CE, LCtx, result);
991 // All other copies return the destination buffer.
992 // (Well, bcopy() has a void return type, but this won't hurt.)
993 state = state->BindExpr(CE, LCtx, destVal);
996 // Invalidate the destination (regular invalidation without pointer-escaping
997 // the address of the top-level region).
998 // FIXME: Even if we can't perfectly model the copy, we should see if we
999 // can use LazyCompoundVals to copy the source values into the destination.
1000 // This would probably remove any existing bindings past the end of the
1001 // copied region, but that's still an improvement over blank invalidation.
1002 state = InvalidateBuffer(C, state, Dest, C.getSVal(Dest),
1003 /*IsSourceBuffer*/false);
1005 // Invalidate the source (const-invalidation without const-pointer-escaping
1006 // the address of the top-level region).
1007 state = InvalidateBuffer(C, state, Source, C.getSVal(Source),
1008 /*IsSourceBuffer*/true);
1010 C.addTransition(state);
1015 void CStringChecker::evalMemcpy(CheckerContext &C, const CallExpr *CE) const {
1016 if (CE->getNumArgs() < 3)
1019 // void *memcpy(void *restrict dst, const void *restrict src, size_t n);
1020 // The return value is the address of the destination buffer.
1021 const Expr *Dest = CE->getArg(0);
1022 ProgramStateRef state = C.getState();
1024 evalCopyCommon(C, CE, state, CE->getArg(2), Dest, CE->getArg(1), true);
1027 void CStringChecker::evalMempcpy(CheckerContext &C, const CallExpr *CE) const {
1028 if (CE->getNumArgs() < 3)
1031 // void *mempcpy(void *restrict dst, const void *restrict src, size_t n);
1032 // The return value is a pointer to the byte following the last written byte.
1033 const Expr *Dest = CE->getArg(0);
1034 ProgramStateRef state = C.getState();
1036 evalCopyCommon(C, CE, state, CE->getArg(2), Dest, CE->getArg(1), true, true);
1039 void CStringChecker::evalMemmove(CheckerContext &C, const CallExpr *CE) const {
1040 if (CE->getNumArgs() < 3)
1043 // void *memmove(void *dst, const void *src, size_t n);
1044 // The return value is the address of the destination buffer.
1045 const Expr *Dest = CE->getArg(0);
1046 ProgramStateRef state = C.getState();
1048 evalCopyCommon(C, CE, state, CE->getArg(2), Dest, CE->getArg(1));
1051 void CStringChecker::evalBcopy(CheckerContext &C, const CallExpr *CE) const {
1052 if (CE->getNumArgs() < 3)
1055 // void bcopy(const void *src, void *dst, size_t n);
1056 evalCopyCommon(C, CE, C.getState(),
1057 CE->getArg(2), CE->getArg(1), CE->getArg(0));
1060 void CStringChecker::evalMemcmp(CheckerContext &C, const CallExpr *CE) const {
1061 if (CE->getNumArgs() < 3)
1064 // int memcmp(const void *s1, const void *s2, size_t n);
1065 CurrentFunctionDescription = "memory comparison function";
1067 const Expr *Left = CE->getArg(0);
1068 const Expr *Right = CE->getArg(1);
1069 const Expr *Size = CE->getArg(2);
1071 ProgramStateRef state = C.getState();
1072 SValBuilder &svalBuilder = C.getSValBuilder();
1074 // See if the size argument is zero.
1075 const LocationContext *LCtx = C.getLocationContext();
1076 SVal sizeVal = state->getSVal(Size, LCtx);
1077 QualType sizeTy = Size->getType();
1079 ProgramStateRef stateZeroSize, stateNonZeroSize;
1080 std::tie(stateZeroSize, stateNonZeroSize) =
1081 assumeZero(C, state, sizeVal, sizeTy);
1083 // If the size can be zero, the result will be 0 in that case, and we don't
1084 // have to check either of the buffers.
1085 if (stateZeroSize) {
1086 state = stateZeroSize;
1087 state = state->BindExpr(CE, LCtx,
1088 svalBuilder.makeZeroVal(CE->getType()));
1089 C.addTransition(state);
1092 // If the size can be nonzero, we have to check the other arguments.
1093 if (stateNonZeroSize) {
1094 state = stateNonZeroSize;
1095 // If we know the two buffers are the same, we know the result is 0.
1096 // First, get the two buffers' addresses. Another checker will have already
1097 // made sure they're not undefined.
1098 DefinedOrUnknownSVal LV =
1099 state->getSVal(Left, LCtx).castAs<DefinedOrUnknownSVal>();
1100 DefinedOrUnknownSVal RV =
1101 state->getSVal(Right, LCtx).castAs<DefinedOrUnknownSVal>();
1103 // See if they are the same.
1104 DefinedOrUnknownSVal SameBuf = svalBuilder.evalEQ(state, LV, RV);
1105 ProgramStateRef StSameBuf, StNotSameBuf;
1106 std::tie(StSameBuf, StNotSameBuf) = state->assume(SameBuf);
1108 // If the two arguments might be the same buffer, we know the result is 0,
1109 // and we only need to check one size.
1112 state = CheckBufferAccess(C, state, Size, Left);
1114 state = StSameBuf->BindExpr(CE, LCtx,
1115 svalBuilder.makeZeroVal(CE->getType()));
1116 C.addTransition(state);
1120 // If the two arguments might be different buffers, we have to check the
1121 // size of both of them.
1123 state = StNotSameBuf;
1124 state = CheckBufferAccess(C, state, Size, Left, Right);
1126 // The return value is the comparison result, which we don't know.
1127 SVal CmpV = svalBuilder.conjureSymbolVal(nullptr, CE, LCtx,
1129 state = state->BindExpr(CE, LCtx, CmpV);
1130 C.addTransition(state);
1136 void CStringChecker::evalstrLength(CheckerContext &C,
1137 const CallExpr *CE) const {
1138 if (CE->getNumArgs() < 1)
1141 // size_t strlen(const char *s);
1142 evalstrLengthCommon(C, CE, /* IsStrnlen = */ false);
1145 void CStringChecker::evalstrnLength(CheckerContext &C,
1146 const CallExpr *CE) const {
1147 if (CE->getNumArgs() < 2)
1150 // size_t strnlen(const char *s, size_t maxlen);
1151 evalstrLengthCommon(C, CE, /* IsStrnlen = */ true);
1154 void CStringChecker::evalstrLengthCommon(CheckerContext &C, const CallExpr *CE,
1155 bool IsStrnlen) const {
1156 CurrentFunctionDescription = "string length function";
1157 ProgramStateRef state = C.getState();
1158 const LocationContext *LCtx = C.getLocationContext();
1161 const Expr *maxlenExpr = CE->getArg(1);
1162 SVal maxlenVal = state->getSVal(maxlenExpr, LCtx);
1164 ProgramStateRef stateZeroSize, stateNonZeroSize;
1165 std::tie(stateZeroSize, stateNonZeroSize) =
1166 assumeZero(C, state, maxlenVal, maxlenExpr->getType());
1168 // If the size can be zero, the result will be 0 in that case, and we don't
1169 // have to check the string itself.
1170 if (stateZeroSize) {
1171 SVal zero = C.getSValBuilder().makeZeroVal(CE->getType());
1172 stateZeroSize = stateZeroSize->BindExpr(CE, LCtx, zero);
1173 C.addTransition(stateZeroSize);
1176 // If the size is GUARANTEED to be zero, we're done!
1177 if (!stateNonZeroSize)
1180 // Otherwise, record the assumption that the size is nonzero.
1181 state = stateNonZeroSize;
1184 // Check that the string argument is non-null.
1185 const Expr *Arg = CE->getArg(0);
1186 SVal ArgVal = state->getSVal(Arg, LCtx);
1188 state = checkNonNull(C, state, Arg, ArgVal);
1193 SVal strLength = getCStringLength(C, state, Arg, ArgVal);
1195 // If the argument isn't a valid C string, there's no valid state to
1197 if (strLength.isUndef())
1200 DefinedOrUnknownSVal result = UnknownVal();
1202 // If the check is for strnlen() then bind the return value to no more than
1203 // the maxlen value.
1205 QualType cmpTy = C.getSValBuilder().getConditionType();
1207 // It's a little unfortunate to be getting this again,
1208 // but it's not that expensive...
1209 const Expr *maxlenExpr = CE->getArg(1);
1210 SVal maxlenVal = state->getSVal(maxlenExpr, LCtx);
1212 Optional<NonLoc> strLengthNL = strLength.getAs<NonLoc>();
1213 Optional<NonLoc> maxlenValNL = maxlenVal.getAs<NonLoc>();
1215 if (strLengthNL && maxlenValNL) {
1216 ProgramStateRef stateStringTooLong, stateStringNotTooLong;
1218 // Check if the strLength is greater than the maxlen.
1219 std::tie(stateStringTooLong, stateStringNotTooLong) = state->assume(
1221 .evalBinOpNN(state, BO_GT, *strLengthNL, *maxlenValNL, cmpTy)
1222 .castAs<DefinedOrUnknownSVal>());
1224 if (stateStringTooLong && !stateStringNotTooLong) {
1225 // If the string is longer than maxlen, return maxlen.
1226 result = *maxlenValNL;
1227 } else if (stateStringNotTooLong && !stateStringTooLong) {
1228 // If the string is shorter than maxlen, return its length.
1229 result = *strLengthNL;
1233 if (result.isUnknown()) {
1234 // If we don't have enough information for a comparison, there's
1235 // no guarantee the full string length will actually be returned.
1236 // All we know is the return value is the min of the string length
1237 // and the limit. This is better than nothing.
1238 result = C.getSValBuilder().conjureSymbolVal(nullptr, CE, LCtx,
1240 NonLoc resultNL = result.castAs<NonLoc>();
1243 state = state->assume(C.getSValBuilder().evalBinOpNN(
1244 state, BO_LE, resultNL, *strLengthNL, cmpTy)
1245 .castAs<DefinedOrUnknownSVal>(), true);
1249 state = state->assume(C.getSValBuilder().evalBinOpNN(
1250 state, BO_LE, resultNL, *maxlenValNL, cmpTy)
1251 .castAs<DefinedOrUnknownSVal>(), true);
1256 // This is a plain strlen(), not strnlen().
1257 result = strLength.castAs<DefinedOrUnknownSVal>();
1259 // If we don't know the length of the string, conjure a return
1260 // value, so it can be used in constraints, at least.
1261 if (result.isUnknown()) {
1262 result = C.getSValBuilder().conjureSymbolVal(nullptr, CE, LCtx,
1267 // Bind the return value.
1268 assert(!result.isUnknown() && "Should have conjured a value by now");
1269 state = state->BindExpr(CE, LCtx, result);
1270 C.addTransition(state);
1273 void CStringChecker::evalStrcpy(CheckerContext &C, const CallExpr *CE) const {
1274 if (CE->getNumArgs() < 2)
1277 // char *strcpy(char *restrict dst, const char *restrict src);
1278 evalStrcpyCommon(C, CE,
1279 /* returnEnd = */ false,
1280 /* isBounded = */ false,
1281 /* isAppending = */ false);
1284 void CStringChecker::evalStrncpy(CheckerContext &C, const CallExpr *CE) const {
1285 if (CE->getNumArgs() < 3)
1288 // char *strncpy(char *restrict dst, const char *restrict src, size_t n);
1289 evalStrcpyCommon(C, CE,
1290 /* returnEnd = */ false,
1291 /* isBounded = */ true,
1292 /* isAppending = */ false);
1295 void CStringChecker::evalStpcpy(CheckerContext &C, const CallExpr *CE) const {
1296 if (CE->getNumArgs() < 2)
1299 // char *stpcpy(char *restrict dst, const char *restrict src);
1300 evalStrcpyCommon(C, CE,
1301 /* returnEnd = */ true,
1302 /* isBounded = */ false,
1303 /* isAppending = */ false);
1306 void CStringChecker::evalStrcat(CheckerContext &C, const CallExpr *CE) const {
1307 if (CE->getNumArgs() < 2)
1310 //char *strcat(char *restrict s1, const char *restrict s2);
1311 evalStrcpyCommon(C, CE,
1312 /* returnEnd = */ false,
1313 /* isBounded = */ false,
1314 /* isAppending = */ true);
1317 void CStringChecker::evalStrncat(CheckerContext &C, const CallExpr *CE) const {
1318 if (CE->getNumArgs() < 3)
1321 //char *strncat(char *restrict s1, const char *restrict s2, size_t n);
1322 evalStrcpyCommon(C, CE,
1323 /* returnEnd = */ false,
1324 /* isBounded = */ true,
1325 /* isAppending = */ true);
1328 void CStringChecker::evalStrcpyCommon(CheckerContext &C, const CallExpr *CE,
1329 bool returnEnd, bool isBounded,
1330 bool isAppending) const {
1331 CurrentFunctionDescription = "string copy function";
1332 ProgramStateRef state = C.getState();
1333 const LocationContext *LCtx = C.getLocationContext();
1335 // Check that the destination is non-null.
1336 const Expr *Dst = CE->getArg(0);
1337 SVal DstVal = state->getSVal(Dst, LCtx);
1339 state = checkNonNull(C, state, Dst, DstVal);
1343 // Check that the source is non-null.
1344 const Expr *srcExpr = CE->getArg(1);
1345 SVal srcVal = state->getSVal(srcExpr, LCtx);
1346 state = checkNonNull(C, state, srcExpr, srcVal);
1350 // Get the string length of the source.
1351 SVal strLength = getCStringLength(C, state, srcExpr, srcVal);
1353 // If the source isn't a valid C string, give up.
1354 if (strLength.isUndef())
1357 SValBuilder &svalBuilder = C.getSValBuilder();
1358 QualType cmpTy = svalBuilder.getConditionType();
1359 QualType sizeTy = svalBuilder.getContext().getSizeType();
1361 // These two values allow checking two kinds of errors:
1362 // - actual overflows caused by a source that doesn't fit in the destination
1363 // - potential overflows caused by a bound that could exceed the destination
1364 SVal amountCopied = UnknownVal();
1365 SVal maxLastElementIndex = UnknownVal();
1366 const char *boundWarning = nullptr;
1368 // If the function is strncpy, strncat, etc... it is bounded.
1370 // Get the max number of characters to copy.
1371 const Expr *lenExpr = CE->getArg(2);
1372 SVal lenVal = state->getSVal(lenExpr, LCtx);
1374 // Protect against misdeclared strncpy().
1375 lenVal = svalBuilder.evalCast(lenVal, sizeTy, lenExpr->getType());
1377 Optional<NonLoc> strLengthNL = strLength.getAs<NonLoc>();
1378 Optional<NonLoc> lenValNL = lenVal.getAs<NonLoc>();
1380 // If we know both values, we might be able to figure out how much
1382 if (strLengthNL && lenValNL) {
1383 ProgramStateRef stateSourceTooLong, stateSourceNotTooLong;
1385 // Check if the max number to copy is less than the length of the src.
1386 // If the bound is equal to the source length, strncpy won't null-
1387 // terminate the result!
1388 std::tie(stateSourceTooLong, stateSourceNotTooLong) = state->assume(
1389 svalBuilder.evalBinOpNN(state, BO_GE, *strLengthNL, *lenValNL, cmpTy)
1390 .castAs<DefinedOrUnknownSVal>());
1392 if (stateSourceTooLong && !stateSourceNotTooLong) {
1393 // Max number to copy is less than the length of the src, so the actual
1394 // strLength copied is the max number arg.
1395 state = stateSourceTooLong;
1396 amountCopied = lenVal;
1398 } else if (!stateSourceTooLong && stateSourceNotTooLong) {
1399 // The source buffer entirely fits in the bound.
1400 state = stateSourceNotTooLong;
1401 amountCopied = strLength;
1405 // We still want to know if the bound is known to be too large.
1408 // For strncat, the check is strlen(dst) + lenVal < sizeof(dst)
1410 // Get the string length of the destination. If the destination is
1411 // memory that can't have a string length, we shouldn't be copying
1413 SVal dstStrLength = getCStringLength(C, state, Dst, DstVal);
1414 if (dstStrLength.isUndef())
1417 if (Optional<NonLoc> dstStrLengthNL = dstStrLength.getAs<NonLoc>()) {
1418 maxLastElementIndex = svalBuilder.evalBinOpNN(state, BO_Add,
1422 boundWarning = "Size argument is greater than the free space in the "
1423 "destination buffer";
1427 // For strncpy, this is just checking that lenVal <= sizeof(dst)
1428 // (Yes, strncpy and strncat differ in how they treat termination.
1429 // strncat ALWAYS terminates, but strncpy doesn't.)
1431 // We need a special case for when the copy size is zero, in which
1432 // case strncpy will do no work at all. Our bounds check uses n-1
1433 // as the last element accessed, so n == 0 is problematic.
1434 ProgramStateRef StateZeroSize, StateNonZeroSize;
1435 std::tie(StateZeroSize, StateNonZeroSize) =
1436 assumeZero(C, state, *lenValNL, sizeTy);
1438 // If the size is known to be zero, we're done.
1439 if (StateZeroSize && !StateNonZeroSize) {
1440 StateZeroSize = StateZeroSize->BindExpr(CE, LCtx, DstVal);
1441 C.addTransition(StateZeroSize);
1445 // Otherwise, go ahead and figure out the last element we'll touch.
1446 // We don't record the non-zero assumption here because we can't
1447 // be sure. We won't warn on a possible zero.
1448 NonLoc one = svalBuilder.makeIntVal(1, sizeTy).castAs<NonLoc>();
1449 maxLastElementIndex = svalBuilder.evalBinOpNN(state, BO_Sub, *lenValNL,
1451 boundWarning = "Size argument is greater than the length of the "
1452 "destination buffer";
1456 // If we couldn't pin down the copy length, at least bound it.
1457 // FIXME: We should actually run this code path for append as well, but
1458 // right now it creates problems with constraints (since we can end up
1459 // trying to pass constraints from symbol to symbol).
1460 if (amountCopied.isUnknown() && !isAppending) {
1461 // Try to get a "hypothetical" string length symbol, which we can later
1462 // set as a real value if that turns out to be the case.
1463 amountCopied = getCStringLength(C, state, lenExpr, srcVal, true);
1464 assert(!amountCopied.isUndef());
1466 if (Optional<NonLoc> amountCopiedNL = amountCopied.getAs<NonLoc>()) {
1468 // amountCopied <= lenVal
1469 SVal copiedLessThanBound = svalBuilder.evalBinOpNN(state, BO_LE,
1473 state = state->assume(
1474 copiedLessThanBound.castAs<DefinedOrUnknownSVal>(), true);
1480 // amountCopied <= strlen(source)
1481 SVal copiedLessThanSrc = svalBuilder.evalBinOpNN(state, BO_LE,
1485 state = state->assume(
1486 copiedLessThanSrc.castAs<DefinedOrUnknownSVal>(), true);
1494 // The function isn't bounded. The amount copied should match the length
1495 // of the source buffer.
1496 amountCopied = strLength;
1501 // This represents the number of characters copied into the destination
1502 // buffer. (It may not actually be the strlen if the destination buffer
1503 // is not terminated.)
1504 SVal finalStrLength = UnknownVal();
1506 // If this is an appending function (strcat, strncat...) then set the
1507 // string length to strlen(src) + strlen(dst) since the buffer will
1508 // ultimately contain both.
1510 // Get the string length of the destination. If the destination is memory
1511 // that can't have a string length, we shouldn't be copying into it anyway.
1512 SVal dstStrLength = getCStringLength(C, state, Dst, DstVal);
1513 if (dstStrLength.isUndef())
1516 Optional<NonLoc> srcStrLengthNL = amountCopied.getAs<NonLoc>();
1517 Optional<NonLoc> dstStrLengthNL = dstStrLength.getAs<NonLoc>();
1519 // If we know both string lengths, we might know the final string length.
1520 if (srcStrLengthNL && dstStrLengthNL) {
1521 // Make sure the two lengths together don't overflow a size_t.
1522 state = checkAdditionOverflow(C, state, *srcStrLengthNL, *dstStrLengthNL);
1526 finalStrLength = svalBuilder.evalBinOpNN(state, BO_Add, *srcStrLengthNL,
1527 *dstStrLengthNL, sizeTy);
1530 // If we couldn't get a single value for the final string length,
1531 // we can at least bound it by the individual lengths.
1532 if (finalStrLength.isUnknown()) {
1533 // Try to get a "hypothetical" string length symbol, which we can later
1534 // set as a real value if that turns out to be the case.
1535 finalStrLength = getCStringLength(C, state, CE, DstVal, true);
1536 assert(!finalStrLength.isUndef());
1538 if (Optional<NonLoc> finalStrLengthNL = finalStrLength.getAs<NonLoc>()) {
1539 if (srcStrLengthNL) {
1540 // finalStrLength >= srcStrLength
1541 SVal sourceInResult = svalBuilder.evalBinOpNN(state, BO_GE,
1545 state = state->assume(sourceInResult.castAs<DefinedOrUnknownSVal>(),
1551 if (dstStrLengthNL) {
1552 // finalStrLength >= dstStrLength
1553 SVal destInResult = svalBuilder.evalBinOpNN(state, BO_GE,
1558 state->assume(destInResult.castAs<DefinedOrUnknownSVal>(), true);
1566 // Otherwise, this is a copy-over function (strcpy, strncpy, ...), and
1567 // the final string length will match the input string length.
1568 finalStrLength = amountCopied;
1571 // The final result of the function will either be a pointer past the last
1572 // copied element, or a pointer to the start of the destination buffer.
1573 SVal Result = (returnEnd ? UnknownVal() : DstVal);
1577 // If the destination is a MemRegion, try to check for a buffer overflow and
1578 // record the new string length.
1579 if (Optional<loc::MemRegionVal> dstRegVal =
1580 DstVal.getAs<loc::MemRegionVal>()) {
1581 QualType ptrTy = Dst->getType();
1583 // If we have an exact value on a bounded copy, use that to check for
1584 // overflows, rather than our estimate about how much is actually copied.
1586 if (Optional<NonLoc> maxLastNL = maxLastElementIndex.getAs<NonLoc>()) {
1587 SVal maxLastElement = svalBuilder.evalBinOpLN(state, BO_Add, *dstRegVal,
1589 state = CheckLocation(C, state, CE->getArg(2), maxLastElement,
1596 // Then, if the final length is known...
1597 if (Optional<NonLoc> knownStrLength = finalStrLength.getAs<NonLoc>()) {
1598 SVal lastElement = svalBuilder.evalBinOpLN(state, BO_Add, *dstRegVal,
1599 *knownStrLength, ptrTy);
1601 // ...and we haven't checked the bound, we'll check the actual copy.
1602 if (!boundWarning) {
1603 const char * const warningMsg =
1604 "String copy function overflows destination buffer";
1605 state = CheckLocation(C, state, Dst, lastElement, warningMsg);
1610 // If this is a stpcpy-style copy, the last element is the return value.
1612 Result = lastElement;
1615 // Invalidate the destination (regular invalidation without pointer-escaping
1616 // the address of the top-level region). This must happen before we set the
1617 // C string length because invalidation will clear the length.
1618 // FIXME: Even if we can't perfectly model the copy, we should see if we
1619 // can use LazyCompoundVals to copy the source values into the destination.
1620 // This would probably remove any existing bindings past the end of the
1621 // string, but that's still an improvement over blank invalidation.
1622 state = InvalidateBuffer(C, state, Dst, *dstRegVal,
1623 /*IsSourceBuffer*/false);
1625 // Invalidate the source (const-invalidation without const-pointer-escaping
1626 // the address of the top-level region).
1627 state = InvalidateBuffer(C, state, srcExpr, srcVal, /*IsSourceBuffer*/true);
1629 // Set the C string length of the destination, if we know it.
1630 if (isBounded && !isAppending) {
1631 // strncpy is annoying in that it doesn't guarantee to null-terminate
1632 // the result string. If the original string didn't fit entirely inside
1633 // the bound (including the null-terminator), we don't know how long the
1635 if (amountCopied != strLength)
1636 finalStrLength = UnknownVal();
1638 state = setCStringLength(state, dstRegVal->getRegion(), finalStrLength);
1643 // If this is a stpcpy-style copy, but we were unable to check for a buffer
1644 // overflow, we still need a result. Conjure a return value.
1645 if (returnEnd && Result.isUnknown()) {
1646 Result = svalBuilder.conjureSymbolVal(nullptr, CE, LCtx, C.blockCount());
1649 // Set the return value.
1650 state = state->BindExpr(CE, LCtx, Result);
1651 C.addTransition(state);
1654 void CStringChecker::evalStrcmp(CheckerContext &C, const CallExpr *CE) const {
1655 if (CE->getNumArgs() < 2)
1658 //int strcmp(const char *s1, const char *s2);
1659 evalStrcmpCommon(C, CE, /* isBounded = */ false, /* ignoreCase = */ false);
1662 void CStringChecker::evalStrncmp(CheckerContext &C, const CallExpr *CE) const {
1663 if (CE->getNumArgs() < 3)
1666 //int strncmp(const char *s1, const char *s2, size_t n);
1667 evalStrcmpCommon(C, CE, /* isBounded = */ true, /* ignoreCase = */ false);
1670 void CStringChecker::evalStrcasecmp(CheckerContext &C,
1671 const CallExpr *CE) const {
1672 if (CE->getNumArgs() < 2)
1675 //int strcasecmp(const char *s1, const char *s2);
1676 evalStrcmpCommon(C, CE, /* isBounded = */ false, /* ignoreCase = */ true);
1679 void CStringChecker::evalStrncasecmp(CheckerContext &C,
1680 const CallExpr *CE) const {
1681 if (CE->getNumArgs() < 3)
1684 //int strncasecmp(const char *s1, const char *s2, size_t n);
1685 evalStrcmpCommon(C, CE, /* isBounded = */ true, /* ignoreCase = */ true);
1688 void CStringChecker::evalStrcmpCommon(CheckerContext &C, const CallExpr *CE,
1689 bool isBounded, bool ignoreCase) const {
1690 CurrentFunctionDescription = "string comparison function";
1691 ProgramStateRef state = C.getState();
1692 const LocationContext *LCtx = C.getLocationContext();
1694 // Check that the first string is non-null
1695 const Expr *s1 = CE->getArg(0);
1696 SVal s1Val = state->getSVal(s1, LCtx);
1697 state = checkNonNull(C, state, s1, s1Val);
1701 // Check that the second string is non-null.
1702 const Expr *s2 = CE->getArg(1);
1703 SVal s2Val = state->getSVal(s2, LCtx);
1704 state = checkNonNull(C, state, s2, s2Val);
1708 // Get the string length of the first string or give up.
1709 SVal s1Length = getCStringLength(C, state, s1, s1Val);
1710 if (s1Length.isUndef())
1713 // Get the string length of the second string or give up.
1714 SVal s2Length = getCStringLength(C, state, s2, s2Val);
1715 if (s2Length.isUndef())
1718 // If we know the two buffers are the same, we know the result is 0.
1719 // First, get the two buffers' addresses. Another checker will have already
1720 // made sure they're not undefined.
1721 DefinedOrUnknownSVal LV = s1Val.castAs<DefinedOrUnknownSVal>();
1722 DefinedOrUnknownSVal RV = s2Val.castAs<DefinedOrUnknownSVal>();
1724 // See if they are the same.
1725 SValBuilder &svalBuilder = C.getSValBuilder();
1726 DefinedOrUnknownSVal SameBuf = svalBuilder.evalEQ(state, LV, RV);
1727 ProgramStateRef StSameBuf, StNotSameBuf;
1728 std::tie(StSameBuf, StNotSameBuf) = state->assume(SameBuf);
1730 // If the two arguments might be the same buffer, we know the result is 0,
1731 // and we only need to check one size.
1733 StSameBuf = StSameBuf->BindExpr(CE, LCtx,
1734 svalBuilder.makeZeroVal(CE->getType()));
1735 C.addTransition(StSameBuf);
1737 // If the two arguments are GUARANTEED to be the same, we're done!
1742 assert(StNotSameBuf);
1743 state = StNotSameBuf;
1745 // At this point we can go about comparing the two buffers.
1746 // For now, we only do this if they're both known string literals.
1748 // Attempt to extract string literals from both expressions.
1749 const StringLiteral *s1StrLiteral = getCStringLiteral(C, state, s1, s1Val);
1750 const StringLiteral *s2StrLiteral = getCStringLiteral(C, state, s2, s2Val);
1751 bool canComputeResult = false;
1753 if (s1StrLiteral && s2StrLiteral) {
1754 StringRef s1StrRef = s1StrLiteral->getString();
1755 StringRef s2StrRef = s2StrLiteral->getString();
1758 // Get the max number of characters to compare.
1759 const Expr *lenExpr = CE->getArg(2);
1760 SVal lenVal = state->getSVal(lenExpr, LCtx);
1762 // If the length is known, we can get the right substrings.
1763 if (const llvm::APSInt *len = svalBuilder.getKnownValue(state, lenVal)) {
1764 // Create substrings of each to compare the prefix.
1765 s1StrRef = s1StrRef.substr(0, (size_t)len->getZExtValue());
1766 s2StrRef = s2StrRef.substr(0, (size_t)len->getZExtValue());
1767 canComputeResult = true;
1770 // This is a normal, unbounded strcmp.
1771 canComputeResult = true;
1774 if (canComputeResult) {
1775 // Real strcmp stops at null characters.
1776 size_t s1Term = s1StrRef.find('\0');
1777 if (s1Term != StringRef::npos)
1778 s1StrRef = s1StrRef.substr(0, s1Term);
1780 size_t s2Term = s2StrRef.find('\0');
1781 if (s2Term != StringRef::npos)
1782 s2StrRef = s2StrRef.substr(0, s2Term);
1784 // Use StringRef's comparison methods to compute the actual result.
1788 // Compare string 1 to string 2 the same way strcasecmp() does.
1789 result = s1StrRef.compare_lower(s2StrRef);
1791 // Compare string 1 to string 2 the same way strcmp() does.
1792 result = s1StrRef.compare(s2StrRef);
1795 // Build the SVal of the comparison and bind the return value.
1796 SVal resultVal = svalBuilder.makeIntVal(result, CE->getType());
1797 state = state->BindExpr(CE, LCtx, resultVal);
1801 if (!canComputeResult) {
1802 // Conjure a symbolic value. It's the best we can do.
1803 SVal resultVal = svalBuilder.conjureSymbolVal(nullptr, CE, LCtx,
1805 state = state->BindExpr(CE, LCtx, resultVal);
1808 // Record this as a possible path.
1809 C.addTransition(state);
1812 void CStringChecker::evalStrsep(CheckerContext &C, const CallExpr *CE) const {
1813 //char *strsep(char **stringp, const char *delim);
1814 if (CE->getNumArgs() < 2)
1817 // Sanity: does the search string parameter match the return type?
1818 const Expr *SearchStrPtr = CE->getArg(0);
1819 QualType CharPtrTy = SearchStrPtr->getType()->getPointeeType();
1820 if (CharPtrTy.isNull() ||
1821 CE->getType().getUnqualifiedType() != CharPtrTy.getUnqualifiedType())
1824 CurrentFunctionDescription = "strsep()";
1825 ProgramStateRef State = C.getState();
1826 const LocationContext *LCtx = C.getLocationContext();
1828 // Check that the search string pointer is non-null (though it may point to
1830 SVal SearchStrVal = State->getSVal(SearchStrPtr, LCtx);
1831 State = checkNonNull(C, State, SearchStrPtr, SearchStrVal);
1835 // Check that the delimiter string is non-null.
1836 const Expr *DelimStr = CE->getArg(1);
1837 SVal DelimStrVal = State->getSVal(DelimStr, LCtx);
1838 State = checkNonNull(C, State, DelimStr, DelimStrVal);
1842 SValBuilder &SVB = C.getSValBuilder();
1844 if (Optional<Loc> SearchStrLoc = SearchStrVal.getAs<Loc>()) {
1845 // Get the current value of the search string pointer, as a char*.
1846 Result = State->getSVal(*SearchStrLoc, CharPtrTy);
1848 // Invalidate the search string, representing the change of one delimiter
1849 // character to NUL.
1850 State = InvalidateBuffer(C, State, SearchStrPtr, Result,
1851 /*IsSourceBuffer*/false);
1853 // Overwrite the search string pointer. The new value is either an address
1854 // further along in the same string, or NULL if there are no more tokens.
1855 State = State->bindLoc(*SearchStrLoc,
1856 SVB.conjureSymbolVal(getTag(), CE, LCtx, CharPtrTy,
1859 assert(SearchStrVal.isUnknown());
1860 // Conjure a symbolic value. It's the best we can do.
1861 Result = SVB.conjureSymbolVal(nullptr, CE, LCtx, C.blockCount());
1864 // Set the return value, and finish.
1865 State = State->BindExpr(CE, LCtx, Result);
1866 C.addTransition(State);
1870 //===----------------------------------------------------------------------===//
1871 // The driver method, and other Checker callbacks.
1872 //===----------------------------------------------------------------------===//
1874 bool CStringChecker::evalCall(const CallExpr *CE, CheckerContext &C) const {
1875 const FunctionDecl *FDecl = C.getCalleeDecl(CE);
1880 // FIXME: Poorly-factored string switches are slow.
1881 FnCheck evalFunction = nullptr;
1882 if (C.isCLibraryFunction(FDecl, "memcpy"))
1883 evalFunction = &CStringChecker::evalMemcpy;
1884 else if (C.isCLibraryFunction(FDecl, "mempcpy"))
1885 evalFunction = &CStringChecker::evalMempcpy;
1886 else if (C.isCLibraryFunction(FDecl, "memcmp"))
1887 evalFunction = &CStringChecker::evalMemcmp;
1888 else if (C.isCLibraryFunction(FDecl, "memmove"))
1889 evalFunction = &CStringChecker::evalMemmove;
1890 else if (C.isCLibraryFunction(FDecl, "strcpy"))
1891 evalFunction = &CStringChecker::evalStrcpy;
1892 else if (C.isCLibraryFunction(FDecl, "strncpy"))
1893 evalFunction = &CStringChecker::evalStrncpy;
1894 else if (C.isCLibraryFunction(FDecl, "stpcpy"))
1895 evalFunction = &CStringChecker::evalStpcpy;
1896 else if (C.isCLibraryFunction(FDecl, "strcat"))
1897 evalFunction = &CStringChecker::evalStrcat;
1898 else if (C.isCLibraryFunction(FDecl, "strncat"))
1899 evalFunction = &CStringChecker::evalStrncat;
1900 else if (C.isCLibraryFunction(FDecl, "strlen"))
1901 evalFunction = &CStringChecker::evalstrLength;
1902 else if (C.isCLibraryFunction(FDecl, "strnlen"))
1903 evalFunction = &CStringChecker::evalstrnLength;
1904 else if (C.isCLibraryFunction(FDecl, "strcmp"))
1905 evalFunction = &CStringChecker::evalStrcmp;
1906 else if (C.isCLibraryFunction(FDecl, "strncmp"))
1907 evalFunction = &CStringChecker::evalStrncmp;
1908 else if (C.isCLibraryFunction(FDecl, "strcasecmp"))
1909 evalFunction = &CStringChecker::evalStrcasecmp;
1910 else if (C.isCLibraryFunction(FDecl, "strncasecmp"))
1911 evalFunction = &CStringChecker::evalStrncasecmp;
1912 else if (C.isCLibraryFunction(FDecl, "strsep"))
1913 evalFunction = &CStringChecker::evalStrsep;
1914 else if (C.isCLibraryFunction(FDecl, "bcopy"))
1915 evalFunction = &CStringChecker::evalBcopy;
1916 else if (C.isCLibraryFunction(FDecl, "bcmp"))
1917 evalFunction = &CStringChecker::evalMemcmp;
1919 // If the callee isn't a string function, let another checker handle it.
1923 // Check and evaluate the call.
1924 (this->*evalFunction)(C, CE);
1926 // If the evaluate call resulted in no change, chain to the next eval call
1928 // Note, the custom CString evaluation calls assume that basic safety
1929 // properties are held. However, if the user chooses to turn off some of these
1930 // checks, we ignore the issues and leave the call evaluation to a generic
1932 if (!C.isDifferent())
1938 void CStringChecker::checkPreStmt(const DeclStmt *DS, CheckerContext &C) const {
1939 // Record string length for char a[] = "abc";
1940 ProgramStateRef state = C.getState();
1942 for (const auto *I : DS->decls()) {
1943 const VarDecl *D = dyn_cast<VarDecl>(I);
1947 // FIXME: Handle array fields of structs.
1948 if (!D->getType()->isArrayType())
1951 const Expr *Init = D->getInit();
1954 if (!isa<StringLiteral>(Init))
1957 Loc VarLoc = state->getLValue(D, C.getLocationContext());
1958 const MemRegion *MR = VarLoc.getAsRegion();
1962 SVal StrVal = state->getSVal(Init, C.getLocationContext());
1963 assert(StrVal.isValid() && "Initializer string is unknown or undefined");
1964 DefinedOrUnknownSVal strLength =
1965 getCStringLength(C, state, Init, StrVal).castAs<DefinedOrUnknownSVal>();
1967 state = state->set<CStringLength>(MR, strLength);
1970 C.addTransition(state);
1973 bool CStringChecker::wantsRegionChangeUpdate(ProgramStateRef state) const {
1974 CStringLengthTy Entries = state->get<CStringLength>();
1975 return !Entries.isEmpty();
1979 CStringChecker::checkRegionChanges(ProgramStateRef state,
1980 const InvalidatedSymbols *,
1981 ArrayRef<const MemRegion *> ExplicitRegions,
1982 ArrayRef<const MemRegion *> Regions,
1983 const CallEvent *Call) const {
1984 CStringLengthTy Entries = state->get<CStringLength>();
1985 if (Entries.isEmpty())
1988 llvm::SmallPtrSet<const MemRegion *, 8> Invalidated;
1989 llvm::SmallPtrSet<const MemRegion *, 32> SuperRegions;
1991 // First build sets for the changed regions and their super-regions.
1992 for (ArrayRef<const MemRegion *>::iterator
1993 I = Regions.begin(), E = Regions.end(); I != E; ++I) {
1994 const MemRegion *MR = *I;
1995 Invalidated.insert(MR);
1997 SuperRegions.insert(MR);
1998 while (const SubRegion *SR = dyn_cast<SubRegion>(MR)) {
1999 MR = SR->getSuperRegion();
2000 SuperRegions.insert(MR);
2004 CStringLengthTy::Factory &F = state->get_context<CStringLength>();
2006 // Then loop over the entries in the current state.
2007 for (CStringLengthTy::iterator I = Entries.begin(),
2008 E = Entries.end(); I != E; ++I) {
2009 const MemRegion *MR = I.getKey();
2011 // Is this entry for a super-region of a changed region?
2012 if (SuperRegions.count(MR)) {
2013 Entries = F.remove(Entries, MR);
2017 // Is this entry for a sub-region of a changed region?
2018 const MemRegion *Super = MR;
2019 while (const SubRegion *SR = dyn_cast<SubRegion>(Super)) {
2020 Super = SR->getSuperRegion();
2021 if (Invalidated.count(Super)) {
2022 Entries = F.remove(Entries, MR);
2028 return state->set<CStringLength>(Entries);
2031 void CStringChecker::checkLiveSymbols(ProgramStateRef state,
2032 SymbolReaper &SR) const {
2033 // Mark all symbols in our string length map as valid.
2034 CStringLengthTy Entries = state->get<CStringLength>();
2036 for (CStringLengthTy::iterator I = Entries.begin(), E = Entries.end();
2038 SVal Len = I.getData();
2040 for (SymExpr::symbol_iterator si = Len.symbol_begin(),
2041 se = Len.symbol_end(); si != se; ++si)
2046 void CStringChecker::checkDeadSymbols(SymbolReaper &SR,
2047 CheckerContext &C) const {
2048 if (!SR.hasDeadSymbols())
2051 ProgramStateRef state = C.getState();
2052 CStringLengthTy Entries = state->get<CStringLength>();
2053 if (Entries.isEmpty())
2056 CStringLengthTy::Factory &F = state->get_context<CStringLength>();
2057 for (CStringLengthTy::iterator I = Entries.begin(), E = Entries.end();
2059 SVal Len = I.getData();
2060 if (SymbolRef Sym = Len.getAsSymbol()) {
2062 Entries = F.remove(Entries, I.getKey());
2066 state = state->set<CStringLength>(Entries);
2067 C.addTransition(state);
2070 #define REGISTER_CHECKER(name) \
2071 void ento::register##name(CheckerManager &mgr) { \
2072 CStringChecker *checker = mgr.registerChecker<CStringChecker>(); \
2073 checker->Filter.Check##name = true; \
2074 checker->Filter.CheckName##name = mgr.getCurrentCheckName(); \
2077 REGISTER_CHECKER(CStringNullArg)
2078 REGISTER_CHECKER(CStringOutOfBounds)
2079 REGISTER_CHECKER(CStringBufferOverlap)
2080 REGISTER_CHECKER(CStringNotNullTerm)
2082 void ento::registerCStringCheckerBasic(CheckerManager &Mgr) {
2083 registerCStringNullArg(Mgr);