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1 //= ProgramState.cpp - Path-Sensitive "State" for tracking values --*- C++ -*--=
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 //  This file implements ProgramState and ProgramStateManager.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
15 #include "clang/Analysis/CFG.h"
16 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
17 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/SubEngine.h"
19 #include "clang/StaticAnalyzer/Core/PathSensitive/TaintManager.h"
20 #include "llvm/Support/raw_ostream.h"
21 
22 using namespace clang;
23 using namespace ento;
24 
25 namespace clang { namespace  ento {
26 /// Increments the number of times this state is referenced.
27 
ProgramStateRetain(const ProgramState * state)28 void ProgramStateRetain(const ProgramState *state) {
29   ++const_cast<ProgramState*>(state)->refCount;
30 }
31 
32 /// Decrement the number of times this state is referenced.
ProgramStateRelease(const ProgramState * state)33 void ProgramStateRelease(const ProgramState *state) {
34   assert(state->refCount > 0);
35   ProgramState *s = const_cast<ProgramState*>(state);
36   if (--s->refCount == 0) {
37     ProgramStateManager &Mgr = s->getStateManager();
38     Mgr.StateSet.RemoveNode(s);
39     s->~ProgramState();
40     Mgr.freeStates.push_back(s);
41   }
42 }
43 }}
44 
ProgramState(ProgramStateManager * mgr,const Environment & env,StoreRef st,GenericDataMap gdm)45 ProgramState::ProgramState(ProgramStateManager *mgr, const Environment& env,
46                  StoreRef st, GenericDataMap gdm)
47   : stateMgr(mgr),
48     Env(env),
49     store(st.getStore()),
50     GDM(gdm),
51     refCount(0) {
52   stateMgr->getStoreManager().incrementReferenceCount(store);
53 }
54 
ProgramState(const ProgramState & RHS)55 ProgramState::ProgramState(const ProgramState &RHS)
56     : llvm::FoldingSetNode(),
57       stateMgr(RHS.stateMgr),
58       Env(RHS.Env),
59       store(RHS.store),
60       GDM(RHS.GDM),
61       refCount(0) {
62   stateMgr->getStoreManager().incrementReferenceCount(store);
63 }
64 
~ProgramState()65 ProgramState::~ProgramState() {
66   if (store)
67     stateMgr->getStoreManager().decrementReferenceCount(store);
68 }
69 
ProgramStateManager(ASTContext & Ctx,StoreManagerCreator CreateSMgr,ConstraintManagerCreator CreateCMgr,llvm::BumpPtrAllocator & alloc,SubEngine * SubEng)70 ProgramStateManager::ProgramStateManager(ASTContext &Ctx,
71                                          StoreManagerCreator CreateSMgr,
72                                          ConstraintManagerCreator CreateCMgr,
73                                          llvm::BumpPtrAllocator &alloc,
74                                          SubEngine *SubEng)
75   : Eng(SubEng), EnvMgr(alloc), GDMFactory(alloc),
76     svalBuilder(createSimpleSValBuilder(alloc, Ctx, *this)),
77     CallEventMgr(new CallEventManager(alloc)), Alloc(alloc) {
78   StoreMgr = (*CreateSMgr)(*this);
79   ConstraintMgr = (*CreateCMgr)(*this, SubEng);
80 }
81 
82 
~ProgramStateManager()83 ProgramStateManager::~ProgramStateManager() {
84   for (GDMContextsTy::iterator I=GDMContexts.begin(), E=GDMContexts.end();
85        I!=E; ++I)
86     I->second.second(I->second.first);
87 }
88 
89 ProgramStateRef
removeDeadBindings(ProgramStateRef state,const StackFrameContext * LCtx,SymbolReaper & SymReaper)90 ProgramStateManager::removeDeadBindings(ProgramStateRef state,
91                                    const StackFrameContext *LCtx,
92                                    SymbolReaper& SymReaper) {
93 
94   // This code essentially performs a "mark-and-sweep" of the VariableBindings.
95   // The roots are any Block-level exprs and Decls that our liveness algorithm
96   // tells us are live.  We then see what Decls they may reference, and keep
97   // those around.  This code more than likely can be made faster, and the
98   // frequency of which this method is called should be experimented with
99   // for optimum performance.
100   ProgramState NewState = *state;
101 
102   NewState.Env = EnvMgr.removeDeadBindings(NewState.Env, SymReaper, state);
103 
104   // Clean up the store.
105   StoreRef newStore = StoreMgr->removeDeadBindings(NewState.getStore(), LCtx,
106                                                    SymReaper);
107   NewState.setStore(newStore);
108   SymReaper.setReapedStore(newStore);
109 
110   ProgramStateRef Result = getPersistentState(NewState);
111   return ConstraintMgr->removeDeadBindings(Result, SymReaper);
112 }
113 
bindLoc(Loc LV,SVal V,bool notifyChanges) const114 ProgramStateRef ProgramState::bindLoc(Loc LV, SVal V, bool notifyChanges) const {
115   ProgramStateManager &Mgr = getStateManager();
116   ProgramStateRef newState = makeWithStore(Mgr.StoreMgr->Bind(getStore(),
117                                                              LV, V));
118   const MemRegion *MR = LV.getAsRegion();
119   if (MR && Mgr.getOwningEngine() && notifyChanges)
120     return Mgr.getOwningEngine()->processRegionChange(newState, MR);
121 
122   return newState;
123 }
124 
bindDefault(SVal loc,SVal V) const125 ProgramStateRef ProgramState::bindDefault(SVal loc, SVal V) const {
126   ProgramStateManager &Mgr = getStateManager();
127   const MemRegion *R = loc.castAs<loc::MemRegionVal>().getRegion();
128   const StoreRef &newStore = Mgr.StoreMgr->BindDefault(getStore(), R, V);
129   ProgramStateRef new_state = makeWithStore(newStore);
130   return Mgr.getOwningEngine() ?
131            Mgr.getOwningEngine()->processRegionChange(new_state, R) :
132            new_state;
133 }
134 
135 typedef ArrayRef<const MemRegion *> RegionList;
136 typedef ArrayRef<SVal> ValueList;
137 
138 ProgramStateRef
invalidateRegions(RegionList Regions,const Expr * E,unsigned Count,const LocationContext * LCtx,bool CausedByPointerEscape,InvalidatedSymbols * IS,const CallEvent * Call,RegionAndSymbolInvalidationTraits * ITraits) const139 ProgramState::invalidateRegions(RegionList Regions,
140                              const Expr *E, unsigned Count,
141                              const LocationContext *LCtx,
142                              bool CausedByPointerEscape,
143                              InvalidatedSymbols *IS,
144                              const CallEvent *Call,
145                              RegionAndSymbolInvalidationTraits *ITraits) const {
146   SmallVector<SVal, 8> Values;
147   for (RegionList::const_iterator I = Regions.begin(),
148                                   End = Regions.end(); I != End; ++I)
149     Values.push_back(loc::MemRegionVal(*I));
150 
151   return invalidateRegionsImpl(Values, E, Count, LCtx, CausedByPointerEscape,
152                                IS, ITraits, Call);
153 }
154 
155 ProgramStateRef
invalidateRegions(ValueList Values,const Expr * E,unsigned Count,const LocationContext * LCtx,bool CausedByPointerEscape,InvalidatedSymbols * IS,const CallEvent * Call,RegionAndSymbolInvalidationTraits * ITraits) const156 ProgramState::invalidateRegions(ValueList Values,
157                              const Expr *E, unsigned Count,
158                              const LocationContext *LCtx,
159                              bool CausedByPointerEscape,
160                              InvalidatedSymbols *IS,
161                              const CallEvent *Call,
162                              RegionAndSymbolInvalidationTraits *ITraits) const {
163 
164   return invalidateRegionsImpl(Values, E, Count, LCtx, CausedByPointerEscape,
165                                IS, ITraits, Call);
166 }
167 
168 ProgramStateRef
invalidateRegionsImpl(ValueList Values,const Expr * E,unsigned Count,const LocationContext * LCtx,bool CausedByPointerEscape,InvalidatedSymbols * IS,RegionAndSymbolInvalidationTraits * ITraits,const CallEvent * Call) const169 ProgramState::invalidateRegionsImpl(ValueList Values,
170                                     const Expr *E, unsigned Count,
171                                     const LocationContext *LCtx,
172                                     bool CausedByPointerEscape,
173                                     InvalidatedSymbols *IS,
174                                     RegionAndSymbolInvalidationTraits *ITraits,
175                                     const CallEvent *Call) const {
176   ProgramStateManager &Mgr = getStateManager();
177   SubEngine* Eng = Mgr.getOwningEngine();
178 
179   InvalidatedSymbols Invalidated;
180   if (!IS)
181     IS = &Invalidated;
182 
183   RegionAndSymbolInvalidationTraits ITraitsLocal;
184   if (!ITraits)
185     ITraits = &ITraitsLocal;
186 
187   if (Eng) {
188     StoreManager::InvalidatedRegions TopLevelInvalidated;
189     StoreManager::InvalidatedRegions Invalidated;
190     const StoreRef &newStore
191     = Mgr.StoreMgr->invalidateRegions(getStore(), Values, E, Count, LCtx, Call,
192                                       *IS, *ITraits, &TopLevelInvalidated,
193                                       &Invalidated);
194 
195     ProgramStateRef newState = makeWithStore(newStore);
196 
197     if (CausedByPointerEscape) {
198       newState = Eng->notifyCheckersOfPointerEscape(newState, IS,
199                                                     TopLevelInvalidated,
200                                                     Invalidated, Call,
201                                                     *ITraits);
202     }
203 
204     return Eng->processRegionChanges(newState, IS, TopLevelInvalidated,
205                                      Invalidated, Call);
206   }
207 
208   const StoreRef &newStore =
209   Mgr.StoreMgr->invalidateRegions(getStore(), Values, E, Count, LCtx, Call,
210                                   *IS, *ITraits, nullptr, nullptr);
211   return makeWithStore(newStore);
212 }
213 
killBinding(Loc LV) const214 ProgramStateRef ProgramState::killBinding(Loc LV) const {
215   assert(!LV.getAs<loc::MemRegionVal>() && "Use invalidateRegion instead.");
216 
217   Store OldStore = getStore();
218   const StoreRef &newStore =
219     getStateManager().StoreMgr->killBinding(OldStore, LV);
220 
221   if (newStore.getStore() == OldStore)
222     return this;
223 
224   return makeWithStore(newStore);
225 }
226 
227 ProgramStateRef
enterStackFrame(const CallEvent & Call,const StackFrameContext * CalleeCtx) const228 ProgramState::enterStackFrame(const CallEvent &Call,
229                               const StackFrameContext *CalleeCtx) const {
230   const StoreRef &NewStore =
231     getStateManager().StoreMgr->enterStackFrame(getStore(), Call, CalleeCtx);
232   return makeWithStore(NewStore);
233 }
234 
getSValAsScalarOrLoc(const MemRegion * R) const235 SVal ProgramState::getSValAsScalarOrLoc(const MemRegion *R) const {
236   // We only want to do fetches from regions that we can actually bind
237   // values.  For example, SymbolicRegions of type 'id<...>' cannot
238   // have direct bindings (but their can be bindings on their subregions).
239   if (!R->isBoundable())
240     return UnknownVal();
241 
242   if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) {
243     QualType T = TR->getValueType();
244     if (Loc::isLocType(T) || T->isIntegralOrEnumerationType())
245       return getSVal(R);
246   }
247 
248   return UnknownVal();
249 }
250 
getSVal(Loc location,QualType T) const251 SVal ProgramState::getSVal(Loc location, QualType T) const {
252   SVal V = getRawSVal(cast<Loc>(location), T);
253 
254   // If 'V' is a symbolic value that is *perfectly* constrained to
255   // be a constant value, use that value instead to lessen the burden
256   // on later analysis stages (so we have less symbolic values to reason
257   // about).
258   if (!T.isNull()) {
259     if (SymbolRef sym = V.getAsSymbol()) {
260       if (const llvm::APSInt *Int = getStateManager()
261                                     .getConstraintManager()
262                                     .getSymVal(this, sym)) {
263         // FIXME: Because we don't correctly model (yet) sign-extension
264         // and truncation of symbolic values, we need to convert
265         // the integer value to the correct signedness and bitwidth.
266         //
267         // This shows up in the following:
268         //
269         //   char foo();
270         //   unsigned x = foo();
271         //   if (x == 54)
272         //     ...
273         //
274         //  The symbolic value stored to 'x' is actually the conjured
275         //  symbol for the call to foo(); the type of that symbol is 'char',
276         //  not unsigned.
277         const llvm::APSInt &NewV = getBasicVals().Convert(T, *Int);
278 
279         if (V.getAs<Loc>())
280           return loc::ConcreteInt(NewV);
281         else
282           return nonloc::ConcreteInt(NewV);
283       }
284     }
285   }
286 
287   return V;
288 }
289 
BindExpr(const Stmt * S,const LocationContext * LCtx,SVal V,bool Invalidate) const290 ProgramStateRef ProgramState::BindExpr(const Stmt *S,
291                                            const LocationContext *LCtx,
292                                            SVal V, bool Invalidate) const{
293   Environment NewEnv =
294     getStateManager().EnvMgr.bindExpr(Env, EnvironmentEntry(S, LCtx), V,
295                                       Invalidate);
296   if (NewEnv == Env)
297     return this;
298 
299   ProgramState NewSt = *this;
300   NewSt.Env = NewEnv;
301   return getStateManager().getPersistentState(NewSt);
302 }
303 
assumeInBound(DefinedOrUnknownSVal Idx,DefinedOrUnknownSVal UpperBound,bool Assumption,QualType indexTy) const304 ProgramStateRef ProgramState::assumeInBound(DefinedOrUnknownSVal Idx,
305                                       DefinedOrUnknownSVal UpperBound,
306                                       bool Assumption,
307                                       QualType indexTy) const {
308   if (Idx.isUnknown() || UpperBound.isUnknown())
309     return this;
310 
311   // Build an expression for 0 <= Idx < UpperBound.
312   // This is the same as Idx + MIN < UpperBound + MIN, if overflow is allowed.
313   // FIXME: This should probably be part of SValBuilder.
314   ProgramStateManager &SM = getStateManager();
315   SValBuilder &svalBuilder = SM.getSValBuilder();
316   ASTContext &Ctx = svalBuilder.getContext();
317 
318   // Get the offset: the minimum value of the array index type.
319   BasicValueFactory &BVF = svalBuilder.getBasicValueFactory();
320   // FIXME: This should be using ValueManager::ArrayindexTy...somehow.
321   if (indexTy.isNull())
322     indexTy = Ctx.IntTy;
323   nonloc::ConcreteInt Min(BVF.getMinValue(indexTy));
324 
325   // Adjust the index.
326   SVal newIdx = svalBuilder.evalBinOpNN(this, BO_Add,
327                                         Idx.castAs<NonLoc>(), Min, indexTy);
328   if (newIdx.isUnknownOrUndef())
329     return this;
330 
331   // Adjust the upper bound.
332   SVal newBound =
333     svalBuilder.evalBinOpNN(this, BO_Add, UpperBound.castAs<NonLoc>(),
334                             Min, indexTy);
335 
336   if (newBound.isUnknownOrUndef())
337     return this;
338 
339   // Build the actual comparison.
340   SVal inBound = svalBuilder.evalBinOpNN(this, BO_LT, newIdx.castAs<NonLoc>(),
341                                          newBound.castAs<NonLoc>(), Ctx.IntTy);
342   if (inBound.isUnknownOrUndef())
343     return this;
344 
345   // Finally, let the constraint manager take care of it.
346   ConstraintManager &CM = SM.getConstraintManager();
347   return CM.assume(this, inBound.castAs<DefinedSVal>(), Assumption);
348 }
349 
isNull(SVal V) const350 ConditionTruthVal ProgramState::isNull(SVal V) const {
351   if (V.isZeroConstant())
352     return true;
353 
354   if (V.isConstant())
355     return false;
356 
357   SymbolRef Sym = V.getAsSymbol(/* IncludeBaseRegion */ true);
358   if (!Sym)
359     return ConditionTruthVal();
360 
361   return getStateManager().ConstraintMgr->isNull(this, Sym);
362 }
363 
getInitialState(const LocationContext * InitLoc)364 ProgramStateRef ProgramStateManager::getInitialState(const LocationContext *InitLoc) {
365   ProgramState State(this,
366                 EnvMgr.getInitialEnvironment(),
367                 StoreMgr->getInitialStore(InitLoc),
368                 GDMFactory.getEmptyMap());
369 
370   return getPersistentState(State);
371 }
372 
getPersistentStateWithGDM(ProgramStateRef FromState,ProgramStateRef GDMState)373 ProgramStateRef ProgramStateManager::getPersistentStateWithGDM(
374                                                      ProgramStateRef FromState,
375                                                      ProgramStateRef GDMState) {
376   ProgramState NewState(*FromState);
377   NewState.GDM = GDMState->GDM;
378   return getPersistentState(NewState);
379 }
380 
getPersistentState(ProgramState & State)381 ProgramStateRef ProgramStateManager::getPersistentState(ProgramState &State) {
382 
383   llvm::FoldingSetNodeID ID;
384   State.Profile(ID);
385   void *InsertPos;
386 
387   if (ProgramState *I = StateSet.FindNodeOrInsertPos(ID, InsertPos))
388     return I;
389 
390   ProgramState *newState = nullptr;
391   if (!freeStates.empty()) {
392     newState = freeStates.back();
393     freeStates.pop_back();
394   }
395   else {
396     newState = (ProgramState*) Alloc.Allocate<ProgramState>();
397   }
398   new (newState) ProgramState(State);
399   StateSet.InsertNode(newState, InsertPos);
400   return newState;
401 }
402 
makeWithStore(const StoreRef & store) const403 ProgramStateRef ProgramState::makeWithStore(const StoreRef &store) const {
404   ProgramState NewSt(*this);
405   NewSt.setStore(store);
406   return getStateManager().getPersistentState(NewSt);
407 }
408 
setStore(const StoreRef & newStore)409 void ProgramState::setStore(const StoreRef &newStore) {
410   Store newStoreStore = newStore.getStore();
411   if (newStoreStore)
412     stateMgr->getStoreManager().incrementReferenceCount(newStoreStore);
413   if (store)
414     stateMgr->getStoreManager().decrementReferenceCount(store);
415   store = newStoreStore;
416 }
417 
418 //===----------------------------------------------------------------------===//
419 //  State pretty-printing.
420 //===----------------------------------------------------------------------===//
421 
print(raw_ostream & Out,const char * NL,const char * Sep) const422 void ProgramState::print(raw_ostream &Out,
423                          const char *NL, const char *Sep) const {
424   // Print the store.
425   ProgramStateManager &Mgr = getStateManager();
426   Mgr.getStoreManager().print(getStore(), Out, NL, Sep);
427 
428   // Print out the environment.
429   Env.print(Out, NL, Sep);
430 
431   // Print out the constraints.
432   Mgr.getConstraintManager().print(this, Out, NL, Sep);
433 
434   // Print checker-specific data.
435   Mgr.getOwningEngine()->printState(Out, this, NL, Sep);
436 }
437 
printDOT(raw_ostream & Out) const438 void ProgramState::printDOT(raw_ostream &Out) const {
439   print(Out, "\\l", "\\|");
440 }
441 
dump() const442 LLVM_DUMP_METHOD void ProgramState::dump() const {
443   print(llvm::errs());
444 }
445 
printTaint(raw_ostream & Out,const char * NL,const char * Sep) const446 void ProgramState::printTaint(raw_ostream &Out,
447                               const char *NL, const char *Sep) const {
448   TaintMapImpl TM = get<TaintMap>();
449 
450   if (!TM.isEmpty())
451     Out <<"Tainted Symbols:" << NL;
452 
453   for (TaintMapImpl::iterator I = TM.begin(), E = TM.end(); I != E; ++I) {
454     Out << I->first << " : " << I->second << NL;
455   }
456 }
457 
dumpTaint() const458 void ProgramState::dumpTaint() const {
459   printTaint(llvm::errs());
460 }
461 
462 //===----------------------------------------------------------------------===//
463 // Generic Data Map.
464 //===----------------------------------------------------------------------===//
465 
FindGDM(void * K) const466 void *const* ProgramState::FindGDM(void *K) const {
467   return GDM.lookup(K);
468 }
469 
470 void*
FindGDMContext(void * K,void * (* CreateContext)(llvm::BumpPtrAllocator &),void (* DeleteContext)(void *))471 ProgramStateManager::FindGDMContext(void *K,
472                                void *(*CreateContext)(llvm::BumpPtrAllocator&),
473                                void (*DeleteContext)(void*)) {
474 
475   std::pair<void*, void (*)(void*)>& p = GDMContexts[K];
476   if (!p.first) {
477     p.first = CreateContext(Alloc);
478     p.second = DeleteContext;
479   }
480 
481   return p.first;
482 }
483 
addGDM(ProgramStateRef St,void * Key,void * Data)484 ProgramStateRef ProgramStateManager::addGDM(ProgramStateRef St, void *Key, void *Data){
485   ProgramState::GenericDataMap M1 = St->getGDM();
486   ProgramState::GenericDataMap M2 = GDMFactory.add(M1, Key, Data);
487 
488   if (M1 == M2)
489     return St;
490 
491   ProgramState NewSt = *St;
492   NewSt.GDM = M2;
493   return getPersistentState(NewSt);
494 }
495 
removeGDM(ProgramStateRef state,void * Key)496 ProgramStateRef ProgramStateManager::removeGDM(ProgramStateRef state, void *Key) {
497   ProgramState::GenericDataMap OldM = state->getGDM();
498   ProgramState::GenericDataMap NewM = GDMFactory.remove(OldM, Key);
499 
500   if (NewM == OldM)
501     return state;
502 
503   ProgramState NewState = *state;
504   NewState.GDM = NewM;
505   return getPersistentState(NewState);
506 }
507 
scan(nonloc::LazyCompoundVal val)508 bool ScanReachableSymbols::scan(nonloc::LazyCompoundVal val) {
509   bool wasVisited = !visited.insert(val.getCVData()).second;
510   if (wasVisited)
511     return true;
512 
513   StoreManager &StoreMgr = state->getStateManager().getStoreManager();
514   // FIXME: We don't really want to use getBaseRegion() here because pointer
515   // arithmetic doesn't apply, but scanReachableSymbols only accepts base
516   // regions right now.
517   const MemRegion *R = val.getRegion()->getBaseRegion();
518   return StoreMgr.scanReachableSymbols(val.getStore(), R, *this);
519 }
520 
scan(nonloc::CompoundVal val)521 bool ScanReachableSymbols::scan(nonloc::CompoundVal val) {
522   for (nonloc::CompoundVal::iterator I=val.begin(), E=val.end(); I!=E; ++I)
523     if (!scan(*I))
524       return false;
525 
526   return true;
527 }
528 
scan(const SymExpr * sym)529 bool ScanReachableSymbols::scan(const SymExpr *sym) {
530   bool wasVisited = !visited.insert(sym).second;
531   if (wasVisited)
532     return true;
533 
534   if (!visitor.VisitSymbol(sym))
535     return false;
536 
537   // TODO: should be rewritten using SymExpr::symbol_iterator.
538   switch (sym->getKind()) {
539     case SymExpr::SymbolRegionValueKind:
540     case SymExpr::SymbolConjuredKind:
541     case SymExpr::SymbolDerivedKind:
542     case SymExpr::SymbolExtentKind:
543     case SymExpr::SymbolMetadataKind:
544       break;
545     case SymExpr::SymbolCastKind:
546       return scan(cast<SymbolCast>(sym)->getOperand());
547     case SymExpr::SymIntExprKind:
548       return scan(cast<SymIntExpr>(sym)->getLHS());
549     case SymExpr::IntSymExprKind:
550       return scan(cast<IntSymExpr>(sym)->getRHS());
551     case SymExpr::SymSymExprKind: {
552       const SymSymExpr *x = cast<SymSymExpr>(sym);
553       return scan(x->getLHS()) && scan(x->getRHS());
554     }
555   }
556   return true;
557 }
558 
scan(SVal val)559 bool ScanReachableSymbols::scan(SVal val) {
560   if (Optional<loc::MemRegionVal> X = val.getAs<loc::MemRegionVal>())
561     return scan(X->getRegion());
562 
563   if (Optional<nonloc::LazyCompoundVal> X =
564           val.getAs<nonloc::LazyCompoundVal>())
565     return scan(*X);
566 
567   if (Optional<nonloc::LocAsInteger> X = val.getAs<nonloc::LocAsInteger>())
568     return scan(X->getLoc());
569 
570   if (SymbolRef Sym = val.getAsSymbol())
571     return scan(Sym);
572 
573   if (const SymExpr *Sym = val.getAsSymbolicExpression())
574     return scan(Sym);
575 
576   if (Optional<nonloc::CompoundVal> X = val.getAs<nonloc::CompoundVal>())
577     return scan(*X);
578 
579   return true;
580 }
581 
scan(const MemRegion * R)582 bool ScanReachableSymbols::scan(const MemRegion *R) {
583   if (isa<MemSpaceRegion>(R))
584     return true;
585 
586   bool wasVisited = !visited.insert(R).second;
587   if (wasVisited)
588     return true;
589 
590   if (!visitor.VisitMemRegion(R))
591     return false;
592 
593   // If this is a symbolic region, visit the symbol for the region.
594   if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
595     if (!visitor.VisitSymbol(SR->getSymbol()))
596       return false;
597 
598   // If this is a subregion, also visit the parent regions.
599   if (const SubRegion *SR = dyn_cast<SubRegion>(R)) {
600     const MemRegion *Super = SR->getSuperRegion();
601     if (!scan(Super))
602       return false;
603 
604     // When we reach the topmost region, scan all symbols in it.
605     if (isa<MemSpaceRegion>(Super)) {
606       StoreManager &StoreMgr = state->getStateManager().getStoreManager();
607       if (!StoreMgr.scanReachableSymbols(state->getStore(), SR, *this))
608         return false;
609     }
610   }
611 
612   // Regions captured by a block are also implicitly reachable.
613   if (const BlockDataRegion *BDR = dyn_cast<BlockDataRegion>(R)) {
614     BlockDataRegion::referenced_vars_iterator I = BDR->referenced_vars_begin(),
615                                               E = BDR->referenced_vars_end();
616     for ( ; I != E; ++I) {
617       if (!scan(I.getCapturedRegion()))
618         return false;
619     }
620   }
621 
622   return true;
623 }
624 
scanReachableSymbols(SVal val,SymbolVisitor & visitor) const625 bool ProgramState::scanReachableSymbols(SVal val, SymbolVisitor& visitor) const {
626   ScanReachableSymbols S(this, visitor);
627   return S.scan(val);
628 }
629 
scanReachableSymbols(const SVal * I,const SVal * E,SymbolVisitor & visitor) const630 bool ProgramState::scanReachableSymbols(const SVal *I, const SVal *E,
631                                    SymbolVisitor &visitor) const {
632   ScanReachableSymbols S(this, visitor);
633   for ( ; I != E; ++I) {
634     if (!S.scan(*I))
635       return false;
636   }
637   return true;
638 }
639 
scanReachableSymbols(const MemRegion * const * I,const MemRegion * const * E,SymbolVisitor & visitor) const640 bool ProgramState::scanReachableSymbols(const MemRegion * const *I,
641                                    const MemRegion * const *E,
642                                    SymbolVisitor &visitor) const {
643   ScanReachableSymbols S(this, visitor);
644   for ( ; I != E; ++I) {
645     if (!S.scan(*I))
646       return false;
647   }
648   return true;
649 }
650 
addTaint(const Stmt * S,const LocationContext * LCtx,TaintTagType Kind) const651 ProgramStateRef ProgramState::addTaint(const Stmt *S,
652                                            const LocationContext *LCtx,
653                                            TaintTagType Kind) const {
654   if (const Expr *E = dyn_cast_or_null<Expr>(S))
655     S = E->IgnoreParens();
656 
657   SymbolRef Sym = getSVal(S, LCtx).getAsSymbol();
658   if (Sym)
659     return addTaint(Sym, Kind);
660 
661   const MemRegion *R = getSVal(S, LCtx).getAsRegion();
662   addTaint(R, Kind);
663 
664   // Cannot add taint, so just return the state.
665   return this;
666 }
667 
addTaint(const MemRegion * R,TaintTagType Kind) const668 ProgramStateRef ProgramState::addTaint(const MemRegion *R,
669                                            TaintTagType Kind) const {
670   if (const SymbolicRegion *SR = dyn_cast_or_null<SymbolicRegion>(R))
671     return addTaint(SR->getSymbol(), Kind);
672   return this;
673 }
674 
addTaint(SymbolRef Sym,TaintTagType Kind) const675 ProgramStateRef ProgramState::addTaint(SymbolRef Sym,
676                                            TaintTagType Kind) const {
677   // If this is a symbol cast, remove the cast before adding the taint. Taint
678   // is cast agnostic.
679   while (const SymbolCast *SC = dyn_cast<SymbolCast>(Sym))
680     Sym = SC->getOperand();
681 
682   ProgramStateRef NewState = set<TaintMap>(Sym, Kind);
683   assert(NewState);
684   return NewState;
685 }
686 
isTainted(const Stmt * S,const LocationContext * LCtx,TaintTagType Kind) const687 bool ProgramState::isTainted(const Stmt *S, const LocationContext *LCtx,
688                              TaintTagType Kind) const {
689   if (const Expr *E = dyn_cast_or_null<Expr>(S))
690     S = E->IgnoreParens();
691 
692   SVal val = getSVal(S, LCtx);
693   return isTainted(val, Kind);
694 }
695 
isTainted(SVal V,TaintTagType Kind) const696 bool ProgramState::isTainted(SVal V, TaintTagType Kind) const {
697   if (const SymExpr *Sym = V.getAsSymExpr())
698     return isTainted(Sym, Kind);
699   if (const MemRegion *Reg = V.getAsRegion())
700     return isTainted(Reg, Kind);
701   return false;
702 }
703 
isTainted(const MemRegion * Reg,TaintTagType K) const704 bool ProgramState::isTainted(const MemRegion *Reg, TaintTagType K) const {
705   if (!Reg)
706     return false;
707 
708   // Element region (array element) is tainted if either the base or the offset
709   // are tainted.
710   if (const ElementRegion *ER = dyn_cast<ElementRegion>(Reg))
711     return isTainted(ER->getSuperRegion(), K) || isTainted(ER->getIndex(), K);
712 
713   if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(Reg))
714     return isTainted(SR->getSymbol(), K);
715 
716   if (const SubRegion *ER = dyn_cast<SubRegion>(Reg))
717     return isTainted(ER->getSuperRegion(), K);
718 
719   return false;
720 }
721 
isTainted(SymbolRef Sym,TaintTagType Kind) const722 bool ProgramState::isTainted(SymbolRef Sym, TaintTagType Kind) const {
723   if (!Sym)
724     return false;
725 
726   // Traverse all the symbols this symbol depends on to see if any are tainted.
727   bool Tainted = false;
728   for (SymExpr::symbol_iterator SI = Sym->symbol_begin(), SE =Sym->symbol_end();
729        SI != SE; ++SI) {
730     if (!isa<SymbolData>(*SI))
731       continue;
732 
733     const TaintTagType *Tag = get<TaintMap>(*SI);
734     Tainted = (Tag && *Tag == Kind);
735 
736     // If this is a SymbolDerived with a tainted parent, it's also tainted.
737     if (const SymbolDerived *SD = dyn_cast<SymbolDerived>(*SI))
738       Tainted = Tainted || isTainted(SD->getParentSymbol(), Kind);
739 
740     // If memory region is tainted, data is also tainted.
741     if (const SymbolRegionValue *SRV = dyn_cast<SymbolRegionValue>(*SI))
742       Tainted = Tainted || isTainted(SRV->getRegion(), Kind);
743 
744     // If If this is a SymbolCast from a tainted value, it's also tainted.
745     if (const SymbolCast *SC = dyn_cast<SymbolCast>(*SI))
746       Tainted = Tainted || isTainted(SC->getOperand(), Kind);
747 
748     if (Tainted)
749       return true;
750   }
751 
752   return Tainted;
753 }
754 
755