1 //===-- StreamChecker.cpp -----------------------------------------*- 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 defines checkers that model and check stream handling functions.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "ClangSACheckers.h"
15 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
16 #include "clang/StaticAnalyzer/Core/Checker.h"
17 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
19 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
21 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
22 #include "llvm/ADT/ImmutableMap.h"
23
24 using namespace clang;
25 using namespace ento;
26
27 namespace {
28
29 struct StreamState {
30 enum Kind { Opened, Closed, OpenFailed, Escaped } K;
31 const Stmt *S;
32
StreamState__anon8c422d8e0111::StreamState33 StreamState(Kind k, const Stmt *s) : K(k), S(s) {}
34
isOpened__anon8c422d8e0111::StreamState35 bool isOpened() const { return K == Opened; }
isClosed__anon8c422d8e0111::StreamState36 bool isClosed() const { return K == Closed; }
37 //bool isOpenFailed() const { return K == OpenFailed; }
38 //bool isEscaped() const { return K == Escaped; }
39
operator ==__anon8c422d8e0111::StreamState40 bool operator==(const StreamState &X) const {
41 return K == X.K && S == X.S;
42 }
43
getOpened__anon8c422d8e0111::StreamState44 static StreamState getOpened(const Stmt *s) { return StreamState(Opened, s); }
getClosed__anon8c422d8e0111::StreamState45 static StreamState getClosed(const Stmt *s) { return StreamState(Closed, s); }
getOpenFailed__anon8c422d8e0111::StreamState46 static StreamState getOpenFailed(const Stmt *s) {
47 return StreamState(OpenFailed, s);
48 }
getEscaped__anon8c422d8e0111::StreamState49 static StreamState getEscaped(const Stmt *s) {
50 return StreamState(Escaped, s);
51 }
52
Profile__anon8c422d8e0111::StreamState53 void Profile(llvm::FoldingSetNodeID &ID) const {
54 ID.AddInteger(K);
55 ID.AddPointer(S);
56 }
57 };
58
59 class StreamChecker : public Checker<eval::Call,
60 check::DeadSymbols > {
61 mutable IdentifierInfo *II_fopen, *II_tmpfile, *II_fclose, *II_fread,
62 *II_fwrite,
63 *II_fseek, *II_ftell, *II_rewind, *II_fgetpos, *II_fsetpos,
64 *II_clearerr, *II_feof, *II_ferror, *II_fileno;
65 mutable std::unique_ptr<BuiltinBug> BT_nullfp, BT_illegalwhence,
66 BT_doubleclose, BT_ResourceLeak;
67
68 public:
StreamChecker()69 StreamChecker()
70 : II_fopen(nullptr), II_tmpfile(nullptr), II_fclose(nullptr),
71 II_fread(nullptr), II_fwrite(nullptr), II_fseek(nullptr),
72 II_ftell(nullptr), II_rewind(nullptr), II_fgetpos(nullptr),
73 II_fsetpos(nullptr), II_clearerr(nullptr), II_feof(nullptr),
74 II_ferror(nullptr), II_fileno(nullptr) {}
75
76 bool evalCall(const CallExpr *CE, CheckerContext &C) const;
77 void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
78
79 private:
80 void Fopen(CheckerContext &C, const CallExpr *CE) const;
81 void Tmpfile(CheckerContext &C, const CallExpr *CE) const;
82 void Fclose(CheckerContext &C, const CallExpr *CE) const;
83 void Fread(CheckerContext &C, const CallExpr *CE) const;
84 void Fwrite(CheckerContext &C, const CallExpr *CE) const;
85 void Fseek(CheckerContext &C, const CallExpr *CE) const;
86 void Ftell(CheckerContext &C, const CallExpr *CE) const;
87 void Rewind(CheckerContext &C, const CallExpr *CE) const;
88 void Fgetpos(CheckerContext &C, const CallExpr *CE) const;
89 void Fsetpos(CheckerContext &C, const CallExpr *CE) const;
90 void Clearerr(CheckerContext &C, const CallExpr *CE) const;
91 void Feof(CheckerContext &C, const CallExpr *CE) const;
92 void Ferror(CheckerContext &C, const CallExpr *CE) const;
93 void Fileno(CheckerContext &C, const CallExpr *CE) const;
94
95 void OpenFileAux(CheckerContext &C, const CallExpr *CE) const;
96
97 ProgramStateRef CheckNullStream(SVal SV, ProgramStateRef state,
98 CheckerContext &C) const;
99 ProgramStateRef CheckDoubleClose(const CallExpr *CE, ProgramStateRef state,
100 CheckerContext &C) const;
101 };
102
103 } // end anonymous namespace
104
REGISTER_MAP_WITH_PROGRAMSTATE(StreamMap,SymbolRef,StreamState)105 REGISTER_MAP_WITH_PROGRAMSTATE(StreamMap, SymbolRef, StreamState)
106
107
108 bool StreamChecker::evalCall(const CallExpr *CE, CheckerContext &C) const {
109 const FunctionDecl *FD = C.getCalleeDecl(CE);
110 if (!FD || FD->getKind() != Decl::Function)
111 return false;
112
113 ASTContext &Ctx = C.getASTContext();
114 if (!II_fopen)
115 II_fopen = &Ctx.Idents.get("fopen");
116 if (!II_tmpfile)
117 II_tmpfile = &Ctx.Idents.get("tmpfile");
118 if (!II_fclose)
119 II_fclose = &Ctx.Idents.get("fclose");
120 if (!II_fread)
121 II_fread = &Ctx.Idents.get("fread");
122 if (!II_fwrite)
123 II_fwrite = &Ctx.Idents.get("fwrite");
124 if (!II_fseek)
125 II_fseek = &Ctx.Idents.get("fseek");
126 if (!II_ftell)
127 II_ftell = &Ctx.Idents.get("ftell");
128 if (!II_rewind)
129 II_rewind = &Ctx.Idents.get("rewind");
130 if (!II_fgetpos)
131 II_fgetpos = &Ctx.Idents.get("fgetpos");
132 if (!II_fsetpos)
133 II_fsetpos = &Ctx.Idents.get("fsetpos");
134 if (!II_clearerr)
135 II_clearerr = &Ctx.Idents.get("clearerr");
136 if (!II_feof)
137 II_feof = &Ctx.Idents.get("feof");
138 if (!II_ferror)
139 II_ferror = &Ctx.Idents.get("ferror");
140 if (!II_fileno)
141 II_fileno = &Ctx.Idents.get("fileno");
142
143 if (FD->getIdentifier() == II_fopen) {
144 Fopen(C, CE);
145 return true;
146 }
147 if (FD->getIdentifier() == II_tmpfile) {
148 Tmpfile(C, CE);
149 return true;
150 }
151 if (FD->getIdentifier() == II_fclose) {
152 Fclose(C, CE);
153 return true;
154 }
155 if (FD->getIdentifier() == II_fread) {
156 Fread(C, CE);
157 return true;
158 }
159 if (FD->getIdentifier() == II_fwrite) {
160 Fwrite(C, CE);
161 return true;
162 }
163 if (FD->getIdentifier() == II_fseek) {
164 Fseek(C, CE);
165 return true;
166 }
167 if (FD->getIdentifier() == II_ftell) {
168 Ftell(C, CE);
169 return true;
170 }
171 if (FD->getIdentifier() == II_rewind) {
172 Rewind(C, CE);
173 return true;
174 }
175 if (FD->getIdentifier() == II_fgetpos) {
176 Fgetpos(C, CE);
177 return true;
178 }
179 if (FD->getIdentifier() == II_fsetpos) {
180 Fsetpos(C, CE);
181 return true;
182 }
183 if (FD->getIdentifier() == II_clearerr) {
184 Clearerr(C, CE);
185 return true;
186 }
187 if (FD->getIdentifier() == II_feof) {
188 Feof(C, CE);
189 return true;
190 }
191 if (FD->getIdentifier() == II_ferror) {
192 Ferror(C, CE);
193 return true;
194 }
195 if (FD->getIdentifier() == II_fileno) {
196 Fileno(C, CE);
197 return true;
198 }
199
200 return false;
201 }
202
Fopen(CheckerContext & C,const CallExpr * CE) const203 void StreamChecker::Fopen(CheckerContext &C, const CallExpr *CE) const {
204 OpenFileAux(C, CE);
205 }
206
Tmpfile(CheckerContext & C,const CallExpr * CE) const207 void StreamChecker::Tmpfile(CheckerContext &C, const CallExpr *CE) const {
208 OpenFileAux(C, CE);
209 }
210
OpenFileAux(CheckerContext & C,const CallExpr * CE) const211 void StreamChecker::OpenFileAux(CheckerContext &C, const CallExpr *CE) const {
212 ProgramStateRef state = C.getState();
213 SValBuilder &svalBuilder = C.getSValBuilder();
214 const LocationContext *LCtx = C.getPredecessor()->getLocationContext();
215 DefinedSVal RetVal = svalBuilder.conjureSymbolVal(nullptr, CE, LCtx,
216 C.blockCount())
217 .castAs<DefinedSVal>();
218 state = state->BindExpr(CE, C.getLocationContext(), RetVal);
219
220 ConstraintManager &CM = C.getConstraintManager();
221 // Bifurcate the state into two: one with a valid FILE* pointer, the other
222 // with a NULL.
223 ProgramStateRef stateNotNull, stateNull;
224 std::tie(stateNotNull, stateNull) = CM.assumeDual(state, RetVal);
225
226 if (SymbolRef Sym = RetVal.getAsSymbol()) {
227 // if RetVal is not NULL, set the symbol's state to Opened.
228 stateNotNull =
229 stateNotNull->set<StreamMap>(Sym,StreamState::getOpened(CE));
230 stateNull =
231 stateNull->set<StreamMap>(Sym, StreamState::getOpenFailed(CE));
232
233 C.addTransition(stateNotNull);
234 C.addTransition(stateNull);
235 }
236 }
237
Fclose(CheckerContext & C,const CallExpr * CE) const238 void StreamChecker::Fclose(CheckerContext &C, const CallExpr *CE) const {
239 ProgramStateRef state = CheckDoubleClose(CE, C.getState(), C);
240 if (state)
241 C.addTransition(state);
242 }
243
Fread(CheckerContext & C,const CallExpr * CE) const244 void StreamChecker::Fread(CheckerContext &C, const CallExpr *CE) const {
245 ProgramStateRef state = C.getState();
246 if (!CheckNullStream(state->getSVal(CE->getArg(3), C.getLocationContext()),
247 state, C))
248 return;
249 }
250
Fwrite(CheckerContext & C,const CallExpr * CE) const251 void StreamChecker::Fwrite(CheckerContext &C, const CallExpr *CE) const {
252 ProgramStateRef state = C.getState();
253 if (!CheckNullStream(state->getSVal(CE->getArg(3), C.getLocationContext()),
254 state, C))
255 return;
256 }
257
Fseek(CheckerContext & C,const CallExpr * CE) const258 void StreamChecker::Fseek(CheckerContext &C, const CallExpr *CE) const {
259 ProgramStateRef state = C.getState();
260 if (!(state = CheckNullStream(state->getSVal(CE->getArg(0),
261 C.getLocationContext()), state, C)))
262 return;
263 // Check the legality of the 'whence' argument of 'fseek'.
264 SVal Whence = state->getSVal(CE->getArg(2), C.getLocationContext());
265 Optional<nonloc::ConcreteInt> CI = Whence.getAs<nonloc::ConcreteInt>();
266
267 if (!CI)
268 return;
269
270 int64_t x = CI->getValue().getSExtValue();
271 if (x >= 0 && x <= 2)
272 return;
273
274 if (ExplodedNode *N = C.generateNonFatalErrorNode(state)) {
275 if (!BT_illegalwhence)
276 BT_illegalwhence.reset(
277 new BuiltinBug(this, "Illegal whence argument",
278 "The whence argument to fseek() should be "
279 "SEEK_SET, SEEK_END, or SEEK_CUR."));
280 C.emitReport(llvm::make_unique<BugReport>(
281 *BT_illegalwhence, BT_illegalwhence->getDescription(), N));
282 }
283 }
284
Ftell(CheckerContext & C,const CallExpr * CE) const285 void StreamChecker::Ftell(CheckerContext &C, const CallExpr *CE) const {
286 ProgramStateRef state = C.getState();
287 if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
288 state, C))
289 return;
290 }
291
Rewind(CheckerContext & C,const CallExpr * CE) const292 void StreamChecker::Rewind(CheckerContext &C, const CallExpr *CE) const {
293 ProgramStateRef state = C.getState();
294 if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
295 state, C))
296 return;
297 }
298
Fgetpos(CheckerContext & C,const CallExpr * CE) const299 void StreamChecker::Fgetpos(CheckerContext &C, const CallExpr *CE) const {
300 ProgramStateRef state = C.getState();
301 if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
302 state, C))
303 return;
304 }
305
Fsetpos(CheckerContext & C,const CallExpr * CE) const306 void StreamChecker::Fsetpos(CheckerContext &C, const CallExpr *CE) const {
307 ProgramStateRef state = C.getState();
308 if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
309 state, C))
310 return;
311 }
312
Clearerr(CheckerContext & C,const CallExpr * CE) const313 void StreamChecker::Clearerr(CheckerContext &C, const CallExpr *CE) const {
314 ProgramStateRef state = C.getState();
315 if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
316 state, C))
317 return;
318 }
319
Feof(CheckerContext & C,const CallExpr * CE) const320 void StreamChecker::Feof(CheckerContext &C, const CallExpr *CE) const {
321 ProgramStateRef state = C.getState();
322 if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
323 state, C))
324 return;
325 }
326
Ferror(CheckerContext & C,const CallExpr * CE) const327 void StreamChecker::Ferror(CheckerContext &C, const CallExpr *CE) const {
328 ProgramStateRef state = C.getState();
329 if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
330 state, C))
331 return;
332 }
333
Fileno(CheckerContext & C,const CallExpr * CE) const334 void StreamChecker::Fileno(CheckerContext &C, const CallExpr *CE) const {
335 ProgramStateRef state = C.getState();
336 if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
337 state, C))
338 return;
339 }
340
CheckNullStream(SVal SV,ProgramStateRef state,CheckerContext & C) const341 ProgramStateRef StreamChecker::CheckNullStream(SVal SV, ProgramStateRef state,
342 CheckerContext &C) const {
343 Optional<DefinedSVal> DV = SV.getAs<DefinedSVal>();
344 if (!DV)
345 return nullptr;
346
347 ConstraintManager &CM = C.getConstraintManager();
348 ProgramStateRef stateNotNull, stateNull;
349 std::tie(stateNotNull, stateNull) = CM.assumeDual(state, *DV);
350
351 if (!stateNotNull && stateNull) {
352 if (ExplodedNode *N = C.generateErrorNode(stateNull)) {
353 if (!BT_nullfp)
354 BT_nullfp.reset(new BuiltinBug(this, "NULL stream pointer",
355 "Stream pointer might be NULL."));
356 C.emitReport(llvm::make_unique<BugReport>(
357 *BT_nullfp, BT_nullfp->getDescription(), N));
358 }
359 return nullptr;
360 }
361 return stateNotNull;
362 }
363
CheckDoubleClose(const CallExpr * CE,ProgramStateRef state,CheckerContext & C) const364 ProgramStateRef StreamChecker::CheckDoubleClose(const CallExpr *CE,
365 ProgramStateRef state,
366 CheckerContext &C) const {
367 SymbolRef Sym =
368 state->getSVal(CE->getArg(0), C.getLocationContext()).getAsSymbol();
369 if (!Sym)
370 return state;
371
372 const StreamState *SS = state->get<StreamMap>(Sym);
373
374 // If the file stream is not tracked, return.
375 if (!SS)
376 return state;
377
378 // Check: Double close a File Descriptor could cause undefined behaviour.
379 // Conforming to man-pages
380 if (SS->isClosed()) {
381 ExplodedNode *N = C.generateErrorNode();
382 if (N) {
383 if (!BT_doubleclose)
384 BT_doubleclose.reset(new BuiltinBug(
385 this, "Double fclose", "Try to close a file Descriptor already"
386 " closed. Cause undefined behaviour."));
387 C.emitReport(llvm::make_unique<BugReport>(
388 *BT_doubleclose, BT_doubleclose->getDescription(), N));
389 }
390 return nullptr;
391 }
392
393 // Close the File Descriptor.
394 return state->set<StreamMap>(Sym, StreamState::getClosed(CE));
395 }
396
checkDeadSymbols(SymbolReaper & SymReaper,CheckerContext & C) const397 void StreamChecker::checkDeadSymbols(SymbolReaper &SymReaper,
398 CheckerContext &C) const {
399 // TODO: Clean up the state.
400 for (SymbolReaper::dead_iterator I = SymReaper.dead_begin(),
401 E = SymReaper.dead_end(); I != E; ++I) {
402 SymbolRef Sym = *I;
403 ProgramStateRef state = C.getState();
404 const StreamState *SS = state->get<StreamMap>(Sym);
405 if (!SS)
406 continue;
407
408 if (SS->isOpened()) {
409 ExplodedNode *N = C.generateErrorNode();
410 if (N) {
411 if (!BT_ResourceLeak)
412 BT_ResourceLeak.reset(new BuiltinBug(
413 this, "Resource Leak",
414 "Opened File never closed. Potential Resource leak."));
415 C.emitReport(llvm::make_unique<BugReport>(
416 *BT_ResourceLeak, BT_ResourceLeak->getDescription(), N));
417 }
418 }
419 }
420 }
421
registerStreamChecker(CheckerManager & mgr)422 void ento::registerStreamChecker(CheckerManager &mgr) {
423 mgr.registerChecker<StreamChecker>();
424 }
425