1 //== GenericTaintChecker.cpp ----------------------------------- -*- 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 checker defines the attack surface for generic taint propagation.
12 // The taint information produced by it might be useful to other checkers. For
13 // example, checkers should report errors which involve tainted data more
14 // aggressively, even if the involved symbols are under constrained.
16 //===----------------------------------------------------------------------===//
17 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
18 #include "clang/AST/Attr.h"
19 #include "clang/Basic/Builtins.h"
20 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
21 #include "clang/StaticAnalyzer/Core/Checker.h"
22 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
23 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
24 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
27 using namespace clang;
31 class GenericTaintChecker
32 : public Checker<check::PostStmt<CallExpr>, check::PreStmt<CallExpr>> {
34 static void *getTag() {
39 void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;
41 void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
44 static const unsigned InvalidArgIndex = UINT_MAX;
45 /// Denotes the return vale.
46 static const unsigned ReturnValueIndex = UINT_MAX - 1;
48 mutable std::unique_ptr<BugType> BT;
49 inline void initBugType() const {
51 BT.reset(new BugType(this, "Use of Untrusted Data", "Untrusted Data"));
54 /// Catch taint related bugs. Check if tainted data is passed to a
56 bool checkPre(const CallExpr *CE, CheckerContext &C) const;
58 /// Add taint sources on a pre-visit.
59 void addSourcesPre(const CallExpr *CE, CheckerContext &C) const;
61 /// Propagate taint generated at pre-visit.
62 bool propagateFromPre(const CallExpr *CE, CheckerContext &C) const;
64 /// Add taint sources on a post visit.
65 void addSourcesPost(const CallExpr *CE, CheckerContext &C) const;
67 /// Check if the region the expression evaluates to is the standard input,
68 /// and thus, is tainted.
69 static bool isStdin(const Expr *E, CheckerContext &C);
71 /// Given a pointer argument, return the value it points to.
72 static Optional<SVal> getPointedToSVal(CheckerContext &C, const Expr *Arg);
74 /// Functions defining the attack surface.
75 typedef ProgramStateRef (GenericTaintChecker::*FnCheck)(
76 const CallExpr *, CheckerContext &C) const;
77 ProgramStateRef postScanf(const CallExpr *CE, CheckerContext &C) const;
78 ProgramStateRef postSocket(const CallExpr *CE, CheckerContext &C) const;
79 ProgramStateRef postRetTaint(const CallExpr *CE, CheckerContext &C) const;
81 /// Taint the scanned input if the file is tainted.
82 ProgramStateRef preFscanf(const CallExpr *CE, CheckerContext &C) const;
84 /// Check for CWE-134: Uncontrolled Format String.
85 static const char MsgUncontrolledFormatString[];
86 bool checkUncontrolledFormatString(const CallExpr *CE,
87 CheckerContext &C) const;
90 /// CERT/STR02-C. "Sanitize data passed to complex subsystems"
91 /// CWE-78, "Failure to Sanitize Data into an OS Command"
92 static const char MsgSanitizeSystemArgs[];
93 bool checkSystemCall(const CallExpr *CE, StringRef Name,
94 CheckerContext &C) const;
96 /// Check if tainted data is used as a buffer size ins strn.. functions,
98 static const char MsgTaintedBufferSize[];
99 bool checkTaintedBufferSize(const CallExpr *CE, const FunctionDecl *FDecl,
100 CheckerContext &C) const;
102 /// Generate a report if the expression is tainted or points to tainted data.
103 bool generateReportIfTainted(const Expr *E, const char Msg[],
104 CheckerContext &C) const;
106 typedef SmallVector<unsigned, 2> ArgVector;
108 /// A struct used to specify taint propagation rules for a function.
110 /// If any of the possible taint source arguments is tainted, all of the
111 /// destination arguments should also be tainted. Use InvalidArgIndex in the
112 /// src list to specify that all of the arguments can introduce taint. Use
113 /// InvalidArgIndex in the dst arguments to signify that all the non-const
114 /// pointer and reference arguments might be tainted on return. If
115 /// ReturnValueIndex is added to the dst list, the return value will be
117 struct TaintPropagationRule {
118 /// List of arguments which can be taint sources and should be checked.
120 /// List of arguments which should be tainted on function return.
122 // TODO: Check if using other data structures would be more optimal.
124 TaintPropagationRule() {}
126 TaintPropagationRule(unsigned SArg, unsigned DArg, bool TaintRet = false) {
127 SrcArgs.push_back(SArg);
128 DstArgs.push_back(DArg);
130 DstArgs.push_back(ReturnValueIndex);
133 TaintPropagationRule(unsigned SArg1, unsigned SArg2, unsigned DArg,
134 bool TaintRet = false) {
135 SrcArgs.push_back(SArg1);
136 SrcArgs.push_back(SArg2);
137 DstArgs.push_back(DArg);
139 DstArgs.push_back(ReturnValueIndex);
142 /// Get the propagation rule for a given function.
143 static TaintPropagationRule
144 getTaintPropagationRule(const FunctionDecl *FDecl, StringRef Name,
147 inline void addSrcArg(unsigned A) { SrcArgs.push_back(A); }
148 inline void addDstArg(unsigned A) { DstArgs.push_back(A); }
150 inline bool isNull() const { return SrcArgs.empty(); }
152 inline bool isDestinationArgument(unsigned ArgNum) const {
153 return (std::find(DstArgs.begin(), DstArgs.end(), ArgNum) !=
157 static inline bool isTaintedOrPointsToTainted(const Expr *E,
158 ProgramStateRef State,
160 if (State->isTainted(E, C.getLocationContext()) || isStdin(E, C))
163 if (!E->getType().getTypePtr()->isPointerType())
166 Optional<SVal> V = getPointedToSVal(C, E);
167 return (V && State->isTainted(*V));
170 /// Pre-process a function which propagates taint according to the
172 ProgramStateRef process(const CallExpr *CE, CheckerContext &C) const;
176 const unsigned GenericTaintChecker::ReturnValueIndex;
177 const unsigned GenericTaintChecker::InvalidArgIndex;
179 const char GenericTaintChecker::MsgUncontrolledFormatString[] =
180 "Untrusted data is used as a format string "
181 "(CWE-134: Uncontrolled Format String)";
183 const char GenericTaintChecker::MsgSanitizeSystemArgs[] =
184 "Untrusted data is passed to a system call "
185 "(CERT/STR02-C. Sanitize data passed to complex subsystems)";
187 const char GenericTaintChecker::MsgTaintedBufferSize[] =
188 "Untrusted data is used to specify the buffer size "
189 "(CERT/STR31-C. Guarantee that storage for strings has sufficient space "
191 "character data and the null terminator)";
193 } // end of anonymous namespace
195 /// A set which is used to pass information from call pre-visit instruction
196 /// to the call post-visit. The values are unsigned integers, which are either
197 /// ReturnValueIndex, or indexes of the pointer/reference argument, which
198 /// points to data, which should be tainted on return.
199 REGISTER_SET_WITH_PROGRAMSTATE(TaintArgsOnPostVisit, unsigned)
201 GenericTaintChecker::TaintPropagationRule
202 GenericTaintChecker::TaintPropagationRule::getTaintPropagationRule(
203 const FunctionDecl *FDecl, StringRef Name, CheckerContext &C) {
204 // TODO: Currently, we might lose precision here: we always mark a return
205 // value as tainted even if it's just a pointer, pointing to tainted data.
207 // Check for exact name match for functions without builtin substitutes.
208 TaintPropagationRule Rule =
209 llvm::StringSwitch<TaintPropagationRule>(Name)
210 .Case("atoi", TaintPropagationRule(0, ReturnValueIndex))
211 .Case("atol", TaintPropagationRule(0, ReturnValueIndex))
212 .Case("atoll", TaintPropagationRule(0, ReturnValueIndex))
213 .Case("getc", TaintPropagationRule(0, ReturnValueIndex))
214 .Case("fgetc", TaintPropagationRule(0, ReturnValueIndex))
215 .Case("getc_unlocked", TaintPropagationRule(0, ReturnValueIndex))
216 .Case("getw", TaintPropagationRule(0, ReturnValueIndex))
217 .Case("toupper", TaintPropagationRule(0, ReturnValueIndex))
218 .Case("tolower", TaintPropagationRule(0, ReturnValueIndex))
219 .Case("strchr", TaintPropagationRule(0, ReturnValueIndex))
220 .Case("strrchr", TaintPropagationRule(0, ReturnValueIndex))
221 .Case("read", TaintPropagationRule(0, 2, 1, true))
222 .Case("pread", TaintPropagationRule(InvalidArgIndex, 1, true))
223 .Case("gets", TaintPropagationRule(InvalidArgIndex, 0, true))
224 .Case("fgets", TaintPropagationRule(2, 0, true))
225 .Case("getline", TaintPropagationRule(2, 0))
226 .Case("getdelim", TaintPropagationRule(3, 0))
227 .Case("fgetln", TaintPropagationRule(0, ReturnValueIndex))
228 .Default(TaintPropagationRule());
233 // Check if it's one of the memory setting/copying functions.
234 // This check is specialized but faster then calling isCLibraryFunction.
236 if ((BId = FDecl->getMemoryFunctionKind()))
238 case Builtin::BImemcpy:
239 case Builtin::BImemmove:
240 case Builtin::BIstrncpy:
241 case Builtin::BIstrncat:
242 return TaintPropagationRule(1, 2, 0, true);
243 case Builtin::BIstrlcpy:
244 case Builtin::BIstrlcat:
245 return TaintPropagationRule(1, 2, 0, false);
246 case Builtin::BIstrndup:
247 return TaintPropagationRule(0, 1, ReturnValueIndex);
253 // Process all other functions which could be defined as builtins.
255 if (C.isCLibraryFunction(FDecl, "snprintf") ||
256 C.isCLibraryFunction(FDecl, "sprintf"))
257 return TaintPropagationRule(InvalidArgIndex, 0, true);
258 else if (C.isCLibraryFunction(FDecl, "strcpy") ||
259 C.isCLibraryFunction(FDecl, "stpcpy") ||
260 C.isCLibraryFunction(FDecl, "strcat"))
261 return TaintPropagationRule(1, 0, true);
262 else if (C.isCLibraryFunction(FDecl, "bcopy"))
263 return TaintPropagationRule(0, 2, 1, false);
264 else if (C.isCLibraryFunction(FDecl, "strdup") ||
265 C.isCLibraryFunction(FDecl, "strdupa"))
266 return TaintPropagationRule(0, ReturnValueIndex);
267 else if (C.isCLibraryFunction(FDecl, "wcsdup"))
268 return TaintPropagationRule(0, ReturnValueIndex);
271 // Skipping the following functions, since they might be used for cleansing
272 // or smart memory copy:
273 // - memccpy - copying until hitting a special character.
275 return TaintPropagationRule();
278 void GenericTaintChecker::checkPreStmt(const CallExpr *CE,
279 CheckerContext &C) const {
280 // Check for errors first.
285 addSourcesPre(CE, C);
288 void GenericTaintChecker::checkPostStmt(const CallExpr *CE,
289 CheckerContext &C) const {
290 if (propagateFromPre(CE, C))
292 addSourcesPost(CE, C);
295 void GenericTaintChecker::addSourcesPre(const CallExpr *CE,
296 CheckerContext &C) const {
297 ProgramStateRef State = nullptr;
298 const FunctionDecl *FDecl = C.getCalleeDecl(CE);
299 if (!FDecl || FDecl->getKind() != Decl::Function)
302 StringRef Name = C.getCalleeName(FDecl);
306 // First, try generating a propagation rule for this function.
307 TaintPropagationRule Rule =
308 TaintPropagationRule::getTaintPropagationRule(FDecl, Name, C);
309 if (!Rule.isNull()) {
310 State = Rule.process(CE, C);
313 C.addTransition(State);
317 // Otherwise, check if we have custom pre-processing implemented.
318 FnCheck evalFunction = llvm::StringSwitch<FnCheck>(Name)
319 .Case("fscanf", &GenericTaintChecker::preFscanf)
321 // Check and evaluate the call.
323 State = (this->*evalFunction)(CE, C);
326 C.addTransition(State);
329 bool GenericTaintChecker::propagateFromPre(const CallExpr *CE,
330 CheckerContext &C) const {
331 ProgramStateRef State = C.getState();
333 // Depending on what was tainted at pre-visit, we determined a set of
334 // arguments which should be tainted after the function returns. These are
335 // stored in the state as TaintArgsOnPostVisit set.
336 TaintArgsOnPostVisitTy TaintArgs = State->get<TaintArgsOnPostVisit>();
337 if (TaintArgs.isEmpty())
340 for (llvm::ImmutableSet<unsigned>::iterator I = TaintArgs.begin(),
343 unsigned ArgNum = *I;
345 // Special handling for the tainted return value.
346 if (ArgNum == ReturnValueIndex) {
347 State = State->addTaint(CE, C.getLocationContext());
351 // The arguments are pointer arguments. The data they are pointing at is
352 // tainted after the call.
353 if (CE->getNumArgs() < (ArgNum + 1))
355 const Expr *Arg = CE->getArg(ArgNum);
356 Optional<SVal> V = getPointedToSVal(C, Arg);
358 State = State->addTaint(*V);
361 // Clear up the taint info from the state.
362 State = State->remove<TaintArgsOnPostVisit>();
364 if (State != C.getState()) {
365 C.addTransition(State);
371 void GenericTaintChecker::addSourcesPost(const CallExpr *CE,
372 CheckerContext &C) const {
373 // Define the attack surface.
374 // Set the evaluation function by switching on the callee name.
375 const FunctionDecl *FDecl = C.getCalleeDecl(CE);
376 if (!FDecl || FDecl->getKind() != Decl::Function)
379 StringRef Name = C.getCalleeName(FDecl);
382 FnCheck evalFunction =
383 llvm::StringSwitch<FnCheck>(Name)
384 .Case("scanf", &GenericTaintChecker::postScanf)
385 // TODO: Add support for vfscanf & family.
386 .Case("getchar", &GenericTaintChecker::postRetTaint)
387 .Case("getchar_unlocked", &GenericTaintChecker::postRetTaint)
388 .Case("getenv", &GenericTaintChecker::postRetTaint)
389 .Case("fopen", &GenericTaintChecker::postRetTaint)
390 .Case("fdopen", &GenericTaintChecker::postRetTaint)
391 .Case("freopen", &GenericTaintChecker::postRetTaint)
392 .Case("getch", &GenericTaintChecker::postRetTaint)
393 .Case("wgetch", &GenericTaintChecker::postRetTaint)
394 .Case("socket", &GenericTaintChecker::postSocket)
397 // If the callee isn't defined, it is not of security concern.
398 // Check and evaluate the call.
399 ProgramStateRef State = nullptr;
401 State = (this->*evalFunction)(CE, C);
405 C.addTransition(State);
408 bool GenericTaintChecker::checkPre(const CallExpr *CE,
409 CheckerContext &C) const {
411 if (checkUncontrolledFormatString(CE, C))
414 const FunctionDecl *FDecl = C.getCalleeDecl(CE);
415 if (!FDecl || FDecl->getKind() != Decl::Function)
418 StringRef Name = C.getCalleeName(FDecl);
422 if (checkSystemCall(CE, Name, C))
425 if (checkTaintedBufferSize(CE, FDecl, C))
431 Optional<SVal> GenericTaintChecker::getPointedToSVal(CheckerContext &C,
433 ProgramStateRef State = C.getState();
434 SVal AddrVal = C.getSVal(Arg->IgnoreParens());
435 if (AddrVal.isUnknownOrUndef())
438 Optional<Loc> AddrLoc = AddrVal.getAs<Loc>();
442 QualType ArgTy = Arg->getType().getCanonicalType();
443 if (!ArgTy->isPointerType())
446 QualType ValTy = ArgTy->getPointeeType();
448 // Do not dereference void pointers. Treat them as byte pointers instead.
449 // FIXME: we might want to consider more than just the first byte.
450 if (ValTy->isVoidType())
451 ValTy = C.getASTContext().CharTy;
453 return State->getSVal(*AddrLoc, ValTy);
457 GenericTaintChecker::TaintPropagationRule::process(const CallExpr *CE,
458 CheckerContext &C) const {
459 ProgramStateRef State = C.getState();
461 // Check for taint in arguments.
462 bool IsTainted = false;
463 for (ArgVector::const_iterator I = SrcArgs.begin(), E = SrcArgs.end(); I != E;
465 unsigned ArgNum = *I;
467 if (ArgNum == InvalidArgIndex) {
468 // Check if any of the arguments is tainted, but skip the
469 // destination arguments.
470 for (unsigned int i = 0; i < CE->getNumArgs(); ++i) {
471 if (isDestinationArgument(i))
473 if ((IsTainted = isTaintedOrPointsToTainted(CE->getArg(i), State, C)))
479 if (CE->getNumArgs() < (ArgNum + 1))
481 if ((IsTainted = isTaintedOrPointsToTainted(CE->getArg(ArgNum), State, C)))
487 // Mark the arguments which should be tainted after the function returns.
488 for (ArgVector::const_iterator I = DstArgs.begin(), E = DstArgs.end(); I != E;
490 unsigned ArgNum = *I;
492 // Should we mark all arguments as tainted?
493 if (ArgNum == InvalidArgIndex) {
494 // For all pointer and references that were passed in:
495 // If they are not pointing to const data, mark data as tainted.
496 // TODO: So far we are just going one level down; ideally we'd need to
498 for (unsigned int i = 0; i < CE->getNumArgs(); ++i) {
499 const Expr *Arg = CE->getArg(i);
500 // Process pointer argument.
501 const Type *ArgTy = Arg->getType().getTypePtr();
502 QualType PType = ArgTy->getPointeeType();
503 if ((!PType.isNull() && !PType.isConstQualified()) ||
504 (ArgTy->isReferenceType() && !Arg->getType().isConstQualified()))
505 State = State->add<TaintArgsOnPostVisit>(i);
510 // Should mark the return value?
511 if (ArgNum == ReturnValueIndex) {
512 State = State->add<TaintArgsOnPostVisit>(ReturnValueIndex);
516 // Mark the given argument.
517 assert(ArgNum < CE->getNumArgs());
518 State = State->add<TaintArgsOnPostVisit>(ArgNum);
524 // If argument 0 (file descriptor) is tainted, all arguments except for arg 0
525 // and arg 1 should get taint.
526 ProgramStateRef GenericTaintChecker::preFscanf(const CallExpr *CE,
527 CheckerContext &C) const {
528 assert(CE->getNumArgs() >= 2);
529 ProgramStateRef State = C.getState();
531 // Check is the file descriptor is tainted.
532 if (State->isTainted(CE->getArg(0), C.getLocationContext()) ||
533 isStdin(CE->getArg(0), C)) {
534 // All arguments except for the first two should get taint.
535 for (unsigned int i = 2; i < CE->getNumArgs(); ++i)
536 State = State->add<TaintArgsOnPostVisit>(i);
543 // If argument 0(protocol domain) is network, the return value should get taint.
544 ProgramStateRef GenericTaintChecker::postSocket(const CallExpr *CE,
545 CheckerContext &C) const {
546 ProgramStateRef State = C.getState();
547 if (CE->getNumArgs() < 3)
550 SourceLocation DomLoc = CE->getArg(0)->getExprLoc();
551 StringRef DomName = C.getMacroNameOrSpelling(DomLoc);
552 // White list the internal communication protocols.
553 if (DomName.equals("AF_SYSTEM") || DomName.equals("AF_LOCAL") ||
554 DomName.equals("AF_UNIX") || DomName.equals("AF_RESERVED_36"))
556 State = State->addTaint(CE, C.getLocationContext());
560 ProgramStateRef GenericTaintChecker::postScanf(const CallExpr *CE,
561 CheckerContext &C) const {
562 ProgramStateRef State = C.getState();
563 if (CE->getNumArgs() < 2)
566 // All arguments except for the very first one should get taint.
567 for (unsigned int i = 1; i < CE->getNumArgs(); ++i) {
568 // The arguments are pointer arguments. The data they are pointing at is
569 // tainted after the call.
570 const Expr *Arg = CE->getArg(i);
571 Optional<SVal> V = getPointedToSVal(C, Arg);
573 State = State->addTaint(*V);
578 ProgramStateRef GenericTaintChecker::postRetTaint(const CallExpr *CE,
579 CheckerContext &C) const {
580 return C.getState()->addTaint(CE, C.getLocationContext());
583 bool GenericTaintChecker::isStdin(const Expr *E, CheckerContext &C) {
584 ProgramStateRef State = C.getState();
585 SVal Val = C.getSVal(E);
587 // stdin is a pointer, so it would be a region.
588 const MemRegion *MemReg = Val.getAsRegion();
590 // The region should be symbolic, we do not know it's value.
591 const SymbolicRegion *SymReg = dyn_cast_or_null<SymbolicRegion>(MemReg);
595 // Get it's symbol and find the declaration region it's pointing to.
596 const SymbolRegionValue *Sm =
597 dyn_cast<SymbolRegionValue>(SymReg->getSymbol());
600 const DeclRegion *DeclReg = dyn_cast_or_null<DeclRegion>(Sm->getRegion());
604 // This region corresponds to a declaration, find out if it's a global/extern
605 // variable named stdin with the proper type.
606 if (const VarDecl *D = dyn_cast_or_null<VarDecl>(DeclReg->getDecl())) {
607 D = D->getCanonicalDecl();
608 if ((D->getName().find("stdin") != StringRef::npos) && D->isExternC())
609 if (const PointerType *PtrTy =
610 dyn_cast<PointerType>(D->getType().getTypePtr()))
611 if (PtrTy->getPointeeType().getCanonicalType() ==
612 C.getASTContext().getFILEType().getCanonicalType())
618 static bool getPrintfFormatArgumentNum(const CallExpr *CE,
619 const CheckerContext &C,
620 unsigned int &ArgNum) {
621 // Find if the function contains a format string argument.
622 // Handles: fprintf, printf, sprintf, snprintf, vfprintf, vprintf, vsprintf,
623 // vsnprintf, syslog, custom annotated functions.
624 const FunctionDecl *FDecl = C.getCalleeDecl(CE);
627 for (const auto *Format : FDecl->specific_attrs<FormatAttr>()) {
628 ArgNum = Format->getFormatIdx() - 1;
629 if ((Format->getType()->getName() == "printf") && CE->getNumArgs() > ArgNum)
633 // Or if a function is named setproctitle (this is a heuristic).
634 if (C.getCalleeName(CE).find("setproctitle") != StringRef::npos) {
642 bool GenericTaintChecker::generateReportIfTainted(const Expr *E,
644 CheckerContext &C) const {
648 ProgramStateRef State = C.getState();
649 Optional<SVal> PointedToSVal = getPointedToSVal(C, E);
651 if (PointedToSVal && State->isTainted(*PointedToSVal))
652 TaintedSVal = *PointedToSVal;
653 else if (State->isTainted(E, C.getLocationContext()))
654 TaintedSVal = C.getSVal(E);
658 // Generate diagnostic.
659 if (ExplodedNode *N = C.generateNonFatalErrorNode()) {
661 auto report = llvm::make_unique<BugReport>(*BT, Msg, N);
662 report->addRange(E->getSourceRange());
663 report->addVisitor(llvm::make_unique<TaintBugVisitor>(TaintedSVal));
664 C.emitReport(std::move(report));
670 bool GenericTaintChecker::checkUncontrolledFormatString(
671 const CallExpr *CE, CheckerContext &C) const {
672 // Check if the function contains a format string argument.
673 unsigned int ArgNum = 0;
674 if (!getPrintfFormatArgumentNum(CE, C, ArgNum))
677 // If either the format string content or the pointer itself are tainted,
679 return generateReportIfTainted(CE->getArg(ArgNum),
680 MsgUncontrolledFormatString, C);
683 bool GenericTaintChecker::checkSystemCall(const CallExpr *CE, StringRef Name,
684 CheckerContext &C) const {
685 // TODO: It might make sense to run this check on demand. In some cases,
686 // we should check if the environment has been cleansed here. We also might
687 // need to know if the user was reset before these calls(seteuid).
688 unsigned ArgNum = llvm::StringSwitch<unsigned>(Name)
701 if (ArgNum == UINT_MAX || CE->getNumArgs() < (ArgNum + 1))
704 return generateReportIfTainted(CE->getArg(ArgNum), MsgSanitizeSystemArgs, C);
707 // TODO: Should this check be a part of the CString checker?
708 // If yes, should taint be a global setting?
709 bool GenericTaintChecker::checkTaintedBufferSize(const CallExpr *CE,
710 const FunctionDecl *FDecl,
711 CheckerContext &C) const {
712 // If the function has a buffer size argument, set ArgNum.
713 unsigned ArgNum = InvalidArgIndex;
715 if ((BId = FDecl->getMemoryFunctionKind()))
717 case Builtin::BImemcpy:
718 case Builtin::BImemmove:
719 case Builtin::BIstrncpy:
722 case Builtin::BIstrndup:
729 if (ArgNum == InvalidArgIndex) {
730 if (C.isCLibraryFunction(FDecl, "malloc") ||
731 C.isCLibraryFunction(FDecl, "calloc") ||
732 C.isCLibraryFunction(FDecl, "alloca"))
734 else if (C.isCLibraryFunction(FDecl, "memccpy"))
736 else if (C.isCLibraryFunction(FDecl, "realloc"))
738 else if (C.isCLibraryFunction(FDecl, "bcopy"))
742 return ArgNum != InvalidArgIndex && CE->getNumArgs() > ArgNum &&
743 generateReportIfTainted(CE->getArg(ArgNum), MsgTaintedBufferSize, C);
746 void ento::registerGenericTaintChecker(CheckerManager &mgr) {
747 mgr.registerChecker<GenericTaintChecker>();