BugReporterVisitors.cpp revision f8ba81e8bbc4d0d424c3b4c3581a9467e972c4de
1// BugReporterVisitors.cpp - Helpers for reporting bugs -----------*- 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 a set of BugReporter "visitors" which can be used to 11// enhance the diagnostics reported for a bug. 12// 13//===----------------------------------------------------------------------===// 14#include "clang/StaticAnalyzer/Core/BugReporter/BugReporterVisitor.h" 15#include "clang/AST/Expr.h" 16#include "clang/AST/ExprObjC.h" 17#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h" 18#include "clang/StaticAnalyzer/Core/BugReporter/PathDiagnostic.h" 19#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h" 20#include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h" 21#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" 22#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" 23#include "llvm/ADT/SmallString.h" 24#include "llvm/ADT/StringExtras.h" 25#include "llvm/Support/raw_ostream.h" 26 27using namespace clang; 28using namespace ento; 29 30using llvm::FoldingSetNodeID; 31 32//===----------------------------------------------------------------------===// 33// Utility functions. 34//===----------------------------------------------------------------------===// 35 36bool bugreporter::isDeclRefExprToReference(const Expr *E) { 37 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) { 38 return DRE->getDecl()->getType()->isReferenceType(); 39 } 40 return false; 41} 42 43const Expr *bugreporter::getDerefExpr(const Stmt *S) { 44 // Pattern match for a few useful cases (do something smarter later): 45 // a[0], p->f, *p 46 const Expr *E = dyn_cast<Expr>(S); 47 if (!E) 48 return 0; 49 E = E->IgnoreParenCasts(); 50 51 while (true) { 52 if (const BinaryOperator *B = dyn_cast<BinaryOperator>(E)) { 53 assert(B->isAssignmentOp()); 54 E = B->getLHS()->IgnoreParenCasts(); 55 continue; 56 } 57 else if (const UnaryOperator *U = dyn_cast<UnaryOperator>(E)) { 58 if (U->getOpcode() == UO_Deref) 59 return U->getSubExpr()->IgnoreParenCasts(); 60 } 61 else if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) { 62 if (ME->isArrow() || isDeclRefExprToReference(ME->getBase())) { 63 return ME->getBase()->IgnoreParenCasts(); 64 } 65 } 66 else if (const ObjCIvarRefExpr *IvarRef = dyn_cast<ObjCIvarRefExpr>(E)) { 67 return IvarRef->getBase()->IgnoreParenCasts(); 68 } 69 else if (const ArraySubscriptExpr *AE = dyn_cast<ArraySubscriptExpr>(E)) { 70 return AE->getBase(); 71 } 72 break; 73 } 74 75 return NULL; 76} 77 78const Stmt *bugreporter::GetDenomExpr(const ExplodedNode *N) { 79 const Stmt *S = N->getLocationAs<PreStmt>()->getStmt(); 80 if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(S)) 81 return BE->getRHS(); 82 return NULL; 83} 84 85const Stmt *bugreporter::GetRetValExpr(const ExplodedNode *N) { 86 const Stmt *S = N->getLocationAs<PostStmt>()->getStmt(); 87 if (const ReturnStmt *RS = dyn_cast<ReturnStmt>(S)) 88 return RS->getRetValue(); 89 return NULL; 90} 91 92//===----------------------------------------------------------------------===// 93// Definitions for bug reporter visitors. 94//===----------------------------------------------------------------------===// 95 96PathDiagnosticPiece* 97BugReporterVisitor::getEndPath(BugReporterContext &BRC, 98 const ExplodedNode *EndPathNode, 99 BugReport &BR) { 100 return 0; 101} 102 103PathDiagnosticPiece* 104BugReporterVisitor::getDefaultEndPath(BugReporterContext &BRC, 105 const ExplodedNode *EndPathNode, 106 BugReport &BR) { 107 PathDiagnosticLocation L = 108 PathDiagnosticLocation::createEndOfPath(EndPathNode,BRC.getSourceManager()); 109 110 BugReport::ranges_iterator Beg, End; 111 llvm::tie(Beg, End) = BR.getRanges(); 112 113 // Only add the statement itself as a range if we didn't specify any 114 // special ranges for this report. 115 PathDiagnosticPiece *P = new PathDiagnosticEventPiece(L, 116 BR.getDescription(), 117 Beg == End); 118 for (; Beg != End; ++Beg) 119 P->addRange(*Beg); 120 121 return P; 122} 123 124 125namespace { 126/// Emits an extra note at the return statement of an interesting stack frame. 127/// 128/// The returned value is marked as an interesting value, and if it's null, 129/// adds a visitor to track where it became null. 130/// 131/// This visitor is intended to be used when another visitor discovers that an 132/// interesting value comes from an inlined function call. 133class ReturnVisitor : public BugReporterVisitorImpl<ReturnVisitor> { 134 const StackFrameContext *StackFrame; 135 enum { 136 Initial, 137 MaybeUnsuppress, 138 Satisfied 139 } Mode; 140 bool InitiallySuppressed; 141 142public: 143 ReturnVisitor(const StackFrameContext *Frame, bool Suppressed) 144 : StackFrame(Frame), Mode(Initial), InitiallySuppressed(Suppressed) {} 145 146 static void *getTag() { 147 static int Tag = 0; 148 return static_cast<void *>(&Tag); 149 } 150 151 virtual void Profile(llvm::FoldingSetNodeID &ID) const { 152 ID.AddPointer(ReturnVisitor::getTag()); 153 ID.AddPointer(StackFrame); 154 ID.AddBoolean(InitiallySuppressed); 155 } 156 157 /// Adds a ReturnVisitor if the given statement represents a call that was 158 /// inlined. 159 /// 160 /// This will search back through the ExplodedGraph, starting from the given 161 /// node, looking for when the given statement was processed. If it turns out 162 /// the statement is a call that was inlined, we add the visitor to the 163 /// bug report, so it can print a note later. 164 static void addVisitorIfNecessary(const ExplodedNode *Node, const Stmt *S, 165 BugReport &BR) { 166 if (!CallEvent::isCallStmt(S)) 167 return; 168 169 // First, find when we processed the statement. 170 do { 171 if (Optional<CallExitEnd> CEE = Node->getLocationAs<CallExitEnd>()) 172 if (CEE->getCalleeContext()->getCallSite() == S) 173 break; 174 if (Optional<StmtPoint> SP = Node->getLocationAs<StmtPoint>()) 175 if (SP->getStmt() == S) 176 break; 177 178 Node = Node->getFirstPred(); 179 } while (Node); 180 181 // Next, step over any post-statement checks. 182 while (Node && Node->getLocation().getAs<PostStmt>()) 183 Node = Node->getFirstPred(); 184 if (!Node) 185 return; 186 187 // Finally, see if we inlined the call. 188 Optional<CallExitEnd> CEE = Node->getLocationAs<CallExitEnd>(); 189 if (!CEE) 190 return; 191 192 const StackFrameContext *CalleeContext = CEE->getCalleeContext(); 193 if (CalleeContext->getCallSite() != S) 194 return; 195 196 // Check the return value. 197 ProgramStateRef State = Node->getState(); 198 SVal RetVal = State->getSVal(S, Node->getLocationContext()); 199 200 // Handle cases where a reference is returned and then immediately used. 201 if (cast<Expr>(S)->isGLValue()) 202 if (Optional<Loc> LValue = RetVal.getAs<Loc>()) 203 RetVal = State->getSVal(*LValue); 204 205 // See if the return value is NULL. If so, suppress the report. 206 SubEngine *Eng = State->getStateManager().getOwningEngine(); 207 assert(Eng && "Cannot file a bug report without an owning engine"); 208 AnalyzerOptions &Options = Eng->getAnalysisManager().options; 209 210 bool InitiallySuppressed = false; 211 if (Options.shouldSuppressNullReturnPaths()) 212 if (Optional<Loc> RetLoc = RetVal.getAs<Loc>()) 213 InitiallySuppressed = !State->assume(*RetLoc, true); 214 215 BR.markInteresting(CalleeContext); 216 BR.addVisitor(new ReturnVisitor(CalleeContext, InitiallySuppressed)); 217 } 218 219 /// Returns true if any counter-suppression heuristics are enabled for 220 /// ReturnVisitor. 221 static bool hasCounterSuppression(AnalyzerOptions &Options) { 222 return Options.shouldAvoidSuppressingNullArgumentPaths(); 223 } 224 225 PathDiagnosticPiece *visitNodeInitial(const ExplodedNode *N, 226 const ExplodedNode *PrevN, 227 BugReporterContext &BRC, 228 BugReport &BR) { 229 // Only print a message at the interesting return statement. 230 if (N->getLocationContext() != StackFrame) 231 return 0; 232 233 Optional<StmtPoint> SP = N->getLocationAs<StmtPoint>(); 234 if (!SP) 235 return 0; 236 237 const ReturnStmt *Ret = dyn_cast<ReturnStmt>(SP->getStmt()); 238 if (!Ret) 239 return 0; 240 241 // Okay, we're at the right return statement, but do we have the return 242 // value available? 243 ProgramStateRef State = N->getState(); 244 SVal V = State->getSVal(Ret, StackFrame); 245 if (V.isUnknownOrUndef()) 246 return 0; 247 248 // Don't print any more notes after this one. 249 Mode = Satisfied; 250 251 const Expr *RetE = Ret->getRetValue(); 252 assert(RetE && "Tracking a return value for a void function"); 253 254 // Handle cases where a reference is returned and then immediately used. 255 Optional<Loc> LValue; 256 if (RetE->isGLValue()) { 257 if ((LValue = V.getAs<Loc>())) { 258 SVal RValue = State->getRawSVal(*LValue, RetE->getType()); 259 if (RValue.getAs<DefinedSVal>()) 260 V = RValue; 261 } 262 } 263 264 // Ignore aggregate rvalues. 265 if (V.getAs<nonloc::LazyCompoundVal>() || 266 V.getAs<nonloc::CompoundVal>()) 267 return 0; 268 269 RetE = RetE->IgnoreParenCasts(); 270 271 // If we can't prove the return value is 0, just mark it interesting, and 272 // make sure to track it into any further inner functions. 273 if (State->assume(V.castAs<DefinedSVal>(), true)) { 274 BR.markInteresting(V); 275 ReturnVisitor::addVisitorIfNecessary(N, RetE, BR); 276 return 0; 277 } 278 279 // If we're returning 0, we should track where that 0 came from. 280 bugreporter::trackNullOrUndefValue(N, RetE, BR); 281 282 // Build an appropriate message based on the return value. 283 SmallString<64> Msg; 284 llvm::raw_svector_ostream Out(Msg); 285 286 if (V.getAs<Loc>()) { 287 // If we have counter-suppression enabled, make sure we keep visiting 288 // future nodes. We want to emit a path note as well, in case 289 // the report is resurrected as valid later on. 290 ExprEngine &Eng = BRC.getBugReporter().getEngine(); 291 AnalyzerOptions &Options = Eng.getAnalysisManager().options; 292 if (InitiallySuppressed && hasCounterSuppression(Options)) 293 Mode = MaybeUnsuppress; 294 295 if (RetE->getType()->isObjCObjectPointerType()) 296 Out << "Returning nil"; 297 else 298 Out << "Returning null pointer"; 299 } else { 300 Out << "Returning zero"; 301 } 302 303 if (LValue) { 304 if (const MemRegion *MR = LValue->getAsRegion()) { 305 if (MR->canPrintPretty()) { 306 Out << " (reference to '"; 307 MR->printPretty(Out); 308 Out << "')"; 309 } 310 } 311 } else { 312 // FIXME: We should have a more generalized location printing mechanism. 313 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetE)) 314 if (const DeclaratorDecl *DD = dyn_cast<DeclaratorDecl>(DR->getDecl())) 315 Out << " (loaded from '" << *DD << "')"; 316 } 317 318 PathDiagnosticLocation L(Ret, BRC.getSourceManager(), StackFrame); 319 return new PathDiagnosticEventPiece(L, Out.str()); 320 } 321 322 PathDiagnosticPiece *visitNodeMaybeUnsuppress(const ExplodedNode *N, 323 const ExplodedNode *PrevN, 324 BugReporterContext &BRC, 325 BugReport &BR) { 326#ifndef NDEBUG 327 ExprEngine &Eng = BRC.getBugReporter().getEngine(); 328 AnalyzerOptions &Options = Eng.getAnalysisManager().options; 329 assert(hasCounterSuppression(Options)); 330#endif 331 332 // Are we at the entry node for this call? 333 Optional<CallEnter> CE = N->getLocationAs<CallEnter>(); 334 if (!CE) 335 return 0; 336 337 if (CE->getCalleeContext() != StackFrame) 338 return 0; 339 340 Mode = Satisfied; 341 342 // Don't automatically suppress a report if one of the arguments is 343 // known to be a null pointer. Instead, start tracking /that/ null 344 // value back to its origin. 345 ProgramStateManager &StateMgr = BRC.getStateManager(); 346 CallEventManager &CallMgr = StateMgr.getCallEventManager(); 347 348 ProgramStateRef State = N->getState(); 349 CallEventRef<> Call = CallMgr.getCaller(StackFrame, State); 350 for (unsigned I = 0, E = Call->getNumArgs(); I != E; ++I) { 351 Optional<Loc> ArgV = Call->getArgSVal(I).getAs<Loc>(); 352 if (!ArgV) 353 continue; 354 355 const Expr *ArgE = Call->getArgExpr(I); 356 if (!ArgE) 357 continue; 358 359 // Is it possible for this argument to be non-null? 360 if (State->assume(*ArgV, true)) 361 continue; 362 363 if (bugreporter::trackNullOrUndefValue(N, ArgE, BR, /*IsArg=*/true)) 364 BR.removeInvalidation(ReturnVisitor::getTag(), StackFrame); 365 366 // If we /can't/ track the null pointer, we should err on the side of 367 // false negatives, and continue towards marking this report invalid. 368 // (We will still look at the other arguments, though.) 369 } 370 371 return 0; 372 } 373 374 PathDiagnosticPiece *VisitNode(const ExplodedNode *N, 375 const ExplodedNode *PrevN, 376 BugReporterContext &BRC, 377 BugReport &BR) { 378 switch (Mode) { 379 case Initial: 380 return visitNodeInitial(N, PrevN, BRC, BR); 381 case MaybeUnsuppress: 382 return visitNodeMaybeUnsuppress(N, PrevN, BRC, BR); 383 case Satisfied: 384 return 0; 385 } 386 387 llvm_unreachable("Invalid visit mode!"); 388 } 389 390 PathDiagnosticPiece *getEndPath(BugReporterContext &BRC, 391 const ExplodedNode *N, 392 BugReport &BR) { 393 if (InitiallySuppressed) 394 BR.markInvalid(ReturnVisitor::getTag(), StackFrame); 395 return 0; 396 } 397}; 398} // end anonymous namespace 399 400 401void FindLastStoreBRVisitor ::Profile(llvm::FoldingSetNodeID &ID) const { 402 static int tag = 0; 403 ID.AddPointer(&tag); 404 ID.AddPointer(R); 405 ID.Add(V); 406} 407 408PathDiagnosticPiece *FindLastStoreBRVisitor::VisitNode(const ExplodedNode *Succ, 409 const ExplodedNode *Pred, 410 BugReporterContext &BRC, 411 BugReport &BR) { 412 413 if (Satisfied) 414 return NULL; 415 416 const ExplodedNode *StoreSite = 0; 417 const Expr *InitE = 0; 418 bool IsParam = false; 419 420 // First see if we reached the declaration of the region. 421 if (const VarRegion *VR = dyn_cast<VarRegion>(R)) { 422 if (Optional<PostStmt> P = Pred->getLocationAs<PostStmt>()) { 423 if (const DeclStmt *DS = P->getStmtAs<DeclStmt>()) { 424 if (DS->getSingleDecl() == VR->getDecl()) { 425 StoreSite = Pred; 426 InitE = VR->getDecl()->getInit(); 427 } 428 } 429 } 430 } 431 432 // Otherwise, see if this is the store site: 433 // (1) Succ has this binding and Pred does not, i.e. this is 434 // where the binding first occurred. 435 // (2) Succ has this binding and is a PostStore node for this region, i.e. 436 // the same binding was re-assigned here. 437 if (!StoreSite) { 438 if (Succ->getState()->getSVal(R) != V) 439 return NULL; 440 441 if (Pred->getState()->getSVal(R) == V) { 442 Optional<PostStore> PS = Succ->getLocationAs<PostStore>(); 443 if (!PS || PS->getLocationValue() != R) 444 return NULL; 445 } 446 447 StoreSite = Succ; 448 449 // If this is an assignment expression, we can track the value 450 // being assigned. 451 if (Optional<PostStmt> P = Succ->getLocationAs<PostStmt>()) 452 if (const BinaryOperator *BO = P->getStmtAs<BinaryOperator>()) 453 if (BO->isAssignmentOp()) 454 InitE = BO->getRHS(); 455 456 // If this is a call entry, the variable should be a parameter. 457 // FIXME: Handle CXXThisRegion as well. (This is not a priority because 458 // 'this' should never be NULL, but this visitor isn't just for NULL and 459 // UndefinedVal.) 460 if (Optional<CallEnter> CE = Succ->getLocationAs<CallEnter>()) { 461 if (const VarRegion *VR = dyn_cast<VarRegion>(R)) { 462 const ParmVarDecl *Param = cast<ParmVarDecl>(VR->getDecl()); 463 464 ProgramStateManager &StateMgr = BRC.getStateManager(); 465 CallEventManager &CallMgr = StateMgr.getCallEventManager(); 466 467 CallEventRef<> Call = CallMgr.getCaller(CE->getCalleeContext(), 468 Succ->getState()); 469 InitE = Call->getArgExpr(Param->getFunctionScopeIndex()); 470 IsParam = true; 471 } 472 } 473 474 // If this is a CXXTempObjectRegion, the Expr responsible for its creation 475 // is wrapped inside of it. 476 if (const CXXTempObjectRegion *TmpR = dyn_cast<CXXTempObjectRegion>(R)) 477 InitE = TmpR->getExpr(); 478 } 479 480 if (!StoreSite) 481 return NULL; 482 Satisfied = true; 483 484 // If we have an expression that provided the value, try to track where it 485 // came from. 486 if (InitE) { 487 if (V.isUndef() || V.getAs<loc::ConcreteInt>()) { 488 if (!IsParam) 489 InitE = InitE->IgnoreParenCasts(); 490 bugreporter::trackNullOrUndefValue(StoreSite, InitE, BR, IsParam); 491 } else { 492 ReturnVisitor::addVisitorIfNecessary(StoreSite, InitE->IgnoreParenCasts(), 493 BR); 494 } 495 } 496 497 if (!R->canPrintPretty()) 498 return 0; 499 500 // Okay, we've found the binding. Emit an appropriate message. 501 SmallString<256> sbuf; 502 llvm::raw_svector_ostream os(sbuf); 503 504 if (Optional<PostStmt> PS = StoreSite->getLocationAs<PostStmt>()) { 505 const Stmt *S = PS->getStmt(); 506 const char *action = 0; 507 const DeclStmt *DS = dyn_cast<DeclStmt>(S); 508 const VarRegion *VR = dyn_cast<VarRegion>(R); 509 510 if (DS) { 511 action = "initialized to "; 512 } else if (isa<BlockExpr>(S)) { 513 action = "captured by block as "; 514 if (VR) { 515 // See if we can get the BlockVarRegion. 516 ProgramStateRef State = StoreSite->getState(); 517 SVal V = State->getSVal(S, PS->getLocationContext()); 518 if (const BlockDataRegion *BDR = 519 dyn_cast_or_null<BlockDataRegion>(V.getAsRegion())) { 520 if (const VarRegion *OriginalR = BDR->getOriginalRegion(VR)) { 521 if (Optional<KnownSVal> KV = 522 State->getSVal(OriginalR).getAs<KnownSVal>()) 523 BR.addVisitor(new FindLastStoreBRVisitor(*KV, OriginalR)); 524 } 525 } 526 } 527 } 528 529 if (action) { 530 if (!R) 531 return 0; 532 533 os << '\''; 534 R->printPretty(os); 535 os << "' "; 536 537 if (V.getAs<loc::ConcreteInt>()) { 538 bool b = false; 539 if (R->isBoundable()) { 540 if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) { 541 if (TR->getValueType()->isObjCObjectPointerType()) { 542 os << action << "nil"; 543 b = true; 544 } 545 } 546 } 547 548 if (!b) 549 os << action << "a null pointer value"; 550 } else if (Optional<nonloc::ConcreteInt> CVal = 551 V.getAs<nonloc::ConcreteInt>()) { 552 os << action << CVal->getValue(); 553 } 554 else if (DS) { 555 if (V.isUndef()) { 556 if (isa<VarRegion>(R)) { 557 const VarDecl *VD = cast<VarDecl>(DS->getSingleDecl()); 558 if (VD->getInit()) 559 os << "initialized to a garbage value"; 560 else 561 os << "declared without an initial value"; 562 } 563 } 564 else { 565 os << "initialized here"; 566 } 567 } 568 } 569 } else if (StoreSite->getLocation().getAs<CallEnter>()) { 570 if (const VarRegion *VR = dyn_cast<VarRegion>(R)) { 571 const ParmVarDecl *Param = cast<ParmVarDecl>(VR->getDecl()); 572 573 os << "Passing "; 574 575 if (V.getAs<loc::ConcreteInt>()) { 576 if (Param->getType()->isObjCObjectPointerType()) 577 os << "nil object reference"; 578 else 579 os << "null pointer value"; 580 } else if (V.isUndef()) { 581 os << "uninitialized value"; 582 } else if (Optional<nonloc::ConcreteInt> CI = 583 V.getAs<nonloc::ConcreteInt>()) { 584 os << "the value " << CI->getValue(); 585 } else { 586 os << "value"; 587 } 588 589 // Printed parameter indexes are 1-based, not 0-based. 590 unsigned Idx = Param->getFunctionScopeIndex() + 1; 591 os << " via " << Idx << llvm::getOrdinalSuffix(Idx) << " parameter '"; 592 593 R->printPretty(os); 594 os << '\''; 595 } 596 } 597 598 if (os.str().empty()) { 599 if (V.getAs<loc::ConcreteInt>()) { 600 bool b = false; 601 if (R->isBoundable()) { 602 if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) { 603 if (TR->getValueType()->isObjCObjectPointerType()) { 604 os << "nil object reference stored to "; 605 b = true; 606 } 607 } 608 } 609 610 if (!b) 611 os << "Null pointer value stored to "; 612 } 613 else if (V.isUndef()) { 614 os << "Uninitialized value stored to "; 615 } else if (Optional<nonloc::ConcreteInt> CV = 616 V.getAs<nonloc::ConcreteInt>()) { 617 os << "The value " << CV->getValue() << " is assigned to "; 618 } 619 else 620 os << "Value assigned to "; 621 622 os << '\''; 623 R->printPretty(os); 624 os << '\''; 625 } 626 627 // Construct a new PathDiagnosticPiece. 628 ProgramPoint P = StoreSite->getLocation(); 629 PathDiagnosticLocation L; 630 if (P.getAs<CallEnter>() && InitE) 631 L = PathDiagnosticLocation(InitE, BRC.getSourceManager(), 632 P.getLocationContext()); 633 else 634 L = PathDiagnosticLocation::create(P, BRC.getSourceManager()); 635 if (!L.isValid()) 636 return NULL; 637 return new PathDiagnosticEventPiece(L, os.str()); 638} 639 640void TrackConstraintBRVisitor::Profile(llvm::FoldingSetNodeID &ID) const { 641 static int tag = 0; 642 ID.AddPointer(&tag); 643 ID.AddBoolean(Assumption); 644 ID.Add(Constraint); 645} 646 647/// Return the tag associated with this visitor. This tag will be used 648/// to make all PathDiagnosticPieces created by this visitor. 649const char *TrackConstraintBRVisitor::getTag() { 650 return "TrackConstraintBRVisitor"; 651} 652 653PathDiagnosticPiece * 654TrackConstraintBRVisitor::VisitNode(const ExplodedNode *N, 655 const ExplodedNode *PrevN, 656 BugReporterContext &BRC, 657 BugReport &BR) { 658 if (isSatisfied) 659 return NULL; 660 661 // Check if in the previous state it was feasible for this constraint 662 // to *not* be true. 663 if (PrevN->getState()->assume(Constraint, !Assumption)) { 664 665 isSatisfied = true; 666 667 // As a sanity check, make sure that the negation of the constraint 668 // was infeasible in the current state. If it is feasible, we somehow 669 // missed the transition point. 670 if (N->getState()->assume(Constraint, !Assumption)) 671 return NULL; 672 673 // We found the transition point for the constraint. We now need to 674 // pretty-print the constraint. (work-in-progress) 675 std::string sbuf; 676 llvm::raw_string_ostream os(sbuf); 677 678 if (Constraint.getAs<Loc>()) { 679 os << "Assuming pointer value is "; 680 os << (Assumption ? "non-null" : "null"); 681 } 682 683 if (os.str().empty()) 684 return NULL; 685 686 // Construct a new PathDiagnosticPiece. 687 ProgramPoint P = N->getLocation(); 688 PathDiagnosticLocation L = 689 PathDiagnosticLocation::create(P, BRC.getSourceManager()); 690 if (!L.isValid()) 691 return NULL; 692 693 PathDiagnosticEventPiece *X = new PathDiagnosticEventPiece(L, os.str()); 694 X->setTag(getTag()); 695 return X; 696 } 697 698 return NULL; 699} 700 701SuppressInlineDefensiveChecksVisitor:: 702SuppressInlineDefensiveChecksVisitor(DefinedSVal Value, const ExplodedNode *N) 703 : V(Value), IsSatisfied(false), IsTrackingTurnedOn(false) { 704 705 // Check if the visitor is disabled. 706 SubEngine *Eng = N->getState()->getStateManager().getOwningEngine(); 707 assert(Eng && "Cannot file a bug report without an owning engine"); 708 AnalyzerOptions &Options = Eng->getAnalysisManager().options; 709 if (!Options.shouldSuppressInlinedDefensiveChecks()) 710 IsSatisfied = true; 711 712 assert(N->getState()->isNull(V).isConstrainedTrue() && 713 "The visitor only tracks the cases where V is constrained to 0"); 714} 715 716void SuppressInlineDefensiveChecksVisitor::Profile(FoldingSetNodeID &ID) const { 717 static int id = 0; 718 ID.AddPointer(&id); 719 ID.Add(V); 720} 721 722const char *SuppressInlineDefensiveChecksVisitor::getTag() { 723 return "IDCVisitor"; 724} 725 726PathDiagnosticPiece * 727SuppressInlineDefensiveChecksVisitor::VisitNode(const ExplodedNode *Succ, 728 const ExplodedNode *Pred, 729 BugReporterContext &BRC, 730 BugReport &BR) { 731 if (IsSatisfied) 732 return 0; 733 734 // Start tracking after we see the first state in which the value is null. 735 if (!IsTrackingTurnedOn) 736 if (Succ->getState()->isNull(V).isConstrainedTrue()) 737 IsTrackingTurnedOn = true; 738 if (!IsTrackingTurnedOn) 739 return 0; 740 741 // Check if in the previous state it was feasible for this value 742 // to *not* be null. 743 if (!Pred->getState()->isNull(V).isConstrainedTrue()) { 744 IsSatisfied = true; 745 746 assert(Succ->getState()->isNull(V).isConstrainedTrue()); 747 748 // Check if this is inlined defensive checks. 749 const LocationContext *CurLC =Succ->getLocationContext(); 750 const LocationContext *ReportLC = BR.getErrorNode()->getLocationContext(); 751 if (CurLC != ReportLC && !CurLC->isParentOf(ReportLC)) 752 BR.markInvalid("Suppress IDC", CurLC); 753 } 754 return 0; 755} 756 757static const MemRegion *getLocationRegionIfReference(const Expr *E, 758 const ExplodedNode *N) { 759 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(E)) { 760 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 761 if (!VD->getType()->isReferenceType()) 762 return 0; 763 ProgramStateManager &StateMgr = N->getState()->getStateManager(); 764 MemRegionManager &MRMgr = StateMgr.getRegionManager(); 765 return MRMgr.getVarRegion(VD, N->getLocationContext()); 766 } 767 } 768 769 // FIXME: This does not handle other kinds of null references, 770 // for example, references from FieldRegions: 771 // struct Wrapper { int &ref; }; 772 // Wrapper w = { *(int *)0 }; 773 // w.ref = 1; 774 775 return 0; 776} 777 778bool bugreporter::trackNullOrUndefValue(const ExplodedNode *N, 779 const Stmt *S, 780 BugReport &report, bool IsArg) { 781 if (!S || !N) 782 return false; 783 784 if (const ExprWithCleanups *EWC = dyn_cast<ExprWithCleanups>(S)) 785 S = EWC->getSubExpr(); 786 if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(S)) 787 S = OVE->getSourceExpr(); 788 789 // Peel off the ternary operator. 790 if (const ConditionalOperator *CO = dyn_cast<ConditionalOperator>(S)) { 791 ProgramStateRef State = N->getState(); 792 SVal CondVal = State->getSVal(CO->getCond(), N->getLocationContext()); 793 if (State->isNull(CondVal).isConstrainedTrue()) { 794 S = CO->getTrueExpr(); 795 } else { 796 assert(State->isNull(CondVal).isConstrainedFalse()); 797 S = CO->getFalseExpr(); 798 } 799 } 800 801 const Expr *Inner = 0; 802 if (const Expr *Ex = dyn_cast<Expr>(S)) { 803 Ex = Ex->IgnoreParenCasts(); 804 if (ExplodedGraph::isInterestingLValueExpr(Ex) || CallEvent::isCallStmt(Ex)) 805 Inner = Ex; 806 } 807 808 if (IsArg) { 809 assert(N->getLocation().getAs<CallEnter>() && "Tracking arg but not at call"); 810 } else { 811 // Walk through nodes until we get one that matches the statement exactly. 812 // Alternately, if we hit a known lvalue for the statement, we know we've 813 // gone too far (though we can likely track the lvalue better anyway). 814 do { 815 const ProgramPoint &pp = N->getLocation(); 816 if (Optional<PostStmt> ps = pp.getAs<PostStmt>()) { 817 if (ps->getStmt() == S || ps->getStmt() == Inner) 818 break; 819 } else if (Optional<CallExitEnd> CEE = pp.getAs<CallExitEnd>()) { 820 if (CEE->getCalleeContext()->getCallSite() == S || 821 CEE->getCalleeContext()->getCallSite() == Inner) 822 break; 823 } 824 N = N->getFirstPred(); 825 } while (N); 826 827 if (!N) 828 return false; 829 } 830 831 ProgramStateRef state = N->getState(); 832 833 // See if the expression we're interested refers to a variable. 834 // If so, we can track both its contents and constraints on its value. 835 if (Inner && ExplodedGraph::isInterestingLValueExpr(Inner)) { 836 const MemRegion *R = 0; 837 838 // Find the ExplodedNode where the lvalue (the value of 'Ex') 839 // was computed. We need this for getting the location value. 840 const ExplodedNode *LVNode = N; 841 while (LVNode) { 842 if (Optional<PostStmt> P = LVNode->getLocation().getAs<PostStmt>()) { 843 if (P->getStmt() == Inner) 844 break; 845 } 846 LVNode = LVNode->getFirstPred(); 847 } 848 assert(LVNode && "Unable to find the lvalue node."); 849 ProgramStateRef LVState = LVNode->getState(); 850 SVal LVal = LVState->getSVal(Inner, LVNode->getLocationContext()); 851 852 if (LVState->isNull(LVal).isConstrainedTrue()) { 853 // In case of C++ references, we want to differentiate between a null 854 // reference and reference to null pointer. 855 // If the LVal is null, check if we are dealing with null reference. 856 // For those, we want to track the location of the reference. 857 if (const MemRegion *RR = getLocationRegionIfReference(Inner, N)) 858 R = RR; 859 } else { 860 R = LVState->getSVal(Inner, LVNode->getLocationContext()).getAsRegion(); 861 862 // If this is a C++ reference to a null pointer, we are tracking the 863 // pointer. In additon, we should find the store at which the reference 864 // got initialized. 865 if (const MemRegion *RR = getLocationRegionIfReference(Inner, N)) { 866 if (Optional<KnownSVal> KV = LVal.getAs<KnownSVal>()) 867 report.addVisitor(new FindLastStoreBRVisitor(*KV, RR)); 868 } 869 } 870 871 if (R) { 872 // Mark both the variable region and its contents as interesting. 873 SVal V = state->getRawSVal(loc::MemRegionVal(R)); 874 875 // If the value matches the default for the variable region, that 876 // might mean that it's been cleared out of the state. Fall back to 877 // the full argument expression (with casts and such intact). 878 if (IsArg) { 879 bool UseArgValue = V.isUnknownOrUndef() || V.isZeroConstant(); 880 if (!UseArgValue) { 881 const SymbolRegionValue *SRV = 882 dyn_cast_or_null<SymbolRegionValue>(V.getAsLocSymbol()); 883 if (SRV) 884 UseArgValue = (SRV->getRegion() == R); 885 } 886 if (UseArgValue) 887 V = state->getSValAsScalarOrLoc(S, N->getLocationContext()); 888 } 889 890 report.markInteresting(R); 891 report.markInteresting(V); 892 report.addVisitor(new UndefOrNullArgVisitor(R)); 893 894 if (isa<SymbolicRegion>(R)) { 895 TrackConstraintBRVisitor *VI = 896 new TrackConstraintBRVisitor(loc::MemRegionVal(R), false); 897 report.addVisitor(VI); 898 } 899 900 // If the contents are symbolic, find out when they became null. 901 if (V.getAsLocSymbol()) { 902 BugReporterVisitor *ConstraintTracker = 903 new TrackConstraintBRVisitor(V.castAs<DefinedSVal>(), false); 904 report.addVisitor(ConstraintTracker); 905 906 // Add visitor, which will suppress inline defensive checks. 907 if (N->getState()->isNull(V).isConstrainedTrue()) { 908 BugReporterVisitor *IDCSuppressor = 909 new SuppressInlineDefensiveChecksVisitor(V.castAs<DefinedSVal>(), 910 N); 911 report.addVisitor(IDCSuppressor); 912 } 913 } 914 915 if (Optional<KnownSVal> KV = V.getAs<KnownSVal>()) 916 report.addVisitor(new FindLastStoreBRVisitor(*KV, R)); 917 return true; 918 } 919 } 920 921 // If the expression is not an "lvalue expression", we can still 922 // track the constraints on its contents. 923 SVal V = state->getSValAsScalarOrLoc(S, N->getLocationContext()); 924 925 // If the value came from an inlined function call, we should at least make 926 // sure that function isn't pruned in our output. 927 if (const Expr *E = dyn_cast<Expr>(S)) 928 S = E->IgnoreParenCasts(); 929 ReturnVisitor::addVisitorIfNecessary(N, S, report); 930 931 // Uncomment this to find cases where we aren't properly getting the 932 // base value that was dereferenced. 933 // assert(!V.isUnknownOrUndef()); 934 // Is it a symbolic value? 935 if (Optional<loc::MemRegionVal> L = V.getAs<loc::MemRegionVal>()) { 936 // At this point we are dealing with the region's LValue. 937 // However, if the rvalue is a symbolic region, we should track it as well. 938 SVal RVal = state->getSVal(L->getRegion()); 939 const MemRegion *RegionRVal = RVal.getAsRegion(); 940 report.addVisitor(new UndefOrNullArgVisitor(L->getRegion())); 941 942 if (RegionRVal && isa<SymbolicRegion>(RegionRVal)) { 943 report.markInteresting(RegionRVal); 944 report.addVisitor(new TrackConstraintBRVisitor( 945 loc::MemRegionVal(RegionRVal), false)); 946 } 947 } 948 949 return true; 950} 951 952BugReporterVisitor * 953FindLastStoreBRVisitor::createVisitorObject(const ExplodedNode *N, 954 const MemRegion *R) { 955 assert(R && "The memory region is null."); 956 957 ProgramStateRef state = N->getState(); 958 if (Optional<KnownSVal> KV = state->getSVal(R).getAs<KnownSVal>()) 959 return new FindLastStoreBRVisitor(*KV, R); 960 return 0; 961} 962 963PathDiagnosticPiece *NilReceiverBRVisitor::VisitNode(const ExplodedNode *N, 964 const ExplodedNode *PrevN, 965 BugReporterContext &BRC, 966 BugReport &BR) { 967 Optional<PostStmt> P = N->getLocationAs<PostStmt>(); 968 if (!P) 969 return 0; 970 const ObjCMessageExpr *ME = P->getStmtAs<ObjCMessageExpr>(); 971 if (!ME) 972 return 0; 973 const Expr *Receiver = ME->getInstanceReceiver(); 974 if (!Receiver) 975 return 0; 976 ProgramStateRef state = N->getState(); 977 const SVal &V = state->getSVal(Receiver, N->getLocationContext()); 978 Optional<DefinedOrUnknownSVal> DV = V.getAs<DefinedOrUnknownSVal>(); 979 if (!DV) 980 return 0; 981 state = state->assume(*DV, true); 982 if (state) 983 return 0; 984 985 // The receiver was nil, and hence the method was skipped. 986 // Register a BugReporterVisitor to issue a message telling us how 987 // the receiver was null. 988 bugreporter::trackNullOrUndefValue(N, Receiver, BR); 989 // Issue a message saying that the method was skipped. 990 PathDiagnosticLocation L(Receiver, BRC.getSourceManager(), 991 N->getLocationContext()); 992 return new PathDiagnosticEventPiece(L, "No method is called " 993 "because the receiver is nil"); 994} 995 996// Registers every VarDecl inside a Stmt with a last store visitor. 997void FindLastStoreBRVisitor::registerStatementVarDecls(BugReport &BR, 998 const Stmt *S) { 999 const ExplodedNode *N = BR.getErrorNode(); 1000 std::deque<const Stmt *> WorkList; 1001 WorkList.push_back(S); 1002 1003 while (!WorkList.empty()) { 1004 const Stmt *Head = WorkList.front(); 1005 WorkList.pop_front(); 1006 1007 ProgramStateRef state = N->getState(); 1008 ProgramStateManager &StateMgr = state->getStateManager(); 1009 1010 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Head)) { 1011 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 1012 const VarRegion *R = 1013 StateMgr.getRegionManager().getVarRegion(VD, N->getLocationContext()); 1014 1015 // What did we load? 1016 SVal V = state->getSVal(S, N->getLocationContext()); 1017 1018 if (V.getAs<loc::ConcreteInt>() || V.getAs<nonloc::ConcreteInt>()) { 1019 // Register a new visitor with the BugReport. 1020 BR.addVisitor(new FindLastStoreBRVisitor(V.castAs<KnownSVal>(), R)); 1021 } 1022 } 1023 } 1024 1025 for (Stmt::const_child_iterator I = Head->child_begin(); 1026 I != Head->child_end(); ++I) 1027 WorkList.push_back(*I); 1028 } 1029} 1030 1031//===----------------------------------------------------------------------===// 1032// Visitor that tries to report interesting diagnostics from conditions. 1033//===----------------------------------------------------------------------===// 1034 1035/// Return the tag associated with this visitor. This tag will be used 1036/// to make all PathDiagnosticPieces created by this visitor. 1037const char *ConditionBRVisitor::getTag() { 1038 return "ConditionBRVisitor"; 1039} 1040 1041PathDiagnosticPiece *ConditionBRVisitor::VisitNode(const ExplodedNode *N, 1042 const ExplodedNode *Prev, 1043 BugReporterContext &BRC, 1044 BugReport &BR) { 1045 PathDiagnosticPiece *piece = VisitNodeImpl(N, Prev, BRC, BR); 1046 if (piece) { 1047 piece->setTag(getTag()); 1048 if (PathDiagnosticEventPiece *ev=dyn_cast<PathDiagnosticEventPiece>(piece)) 1049 ev->setPrunable(true, /* override */ false); 1050 } 1051 return piece; 1052} 1053 1054PathDiagnosticPiece *ConditionBRVisitor::VisitNodeImpl(const ExplodedNode *N, 1055 const ExplodedNode *Prev, 1056 BugReporterContext &BRC, 1057 BugReport &BR) { 1058 1059 ProgramPoint progPoint = N->getLocation(); 1060 ProgramStateRef CurrentState = N->getState(); 1061 ProgramStateRef PrevState = Prev->getState(); 1062 1063 // Compare the GDMs of the state, because that is where constraints 1064 // are managed. Note that ensure that we only look at nodes that 1065 // were generated by the analyzer engine proper, not checkers. 1066 if (CurrentState->getGDM().getRoot() == 1067 PrevState->getGDM().getRoot()) 1068 return 0; 1069 1070 // If an assumption was made on a branch, it should be caught 1071 // here by looking at the state transition. 1072 if (Optional<BlockEdge> BE = progPoint.getAs<BlockEdge>()) { 1073 const CFGBlock *srcBlk = BE->getSrc(); 1074 if (const Stmt *term = srcBlk->getTerminator()) 1075 return VisitTerminator(term, N, srcBlk, BE->getDst(), BR, BRC); 1076 return 0; 1077 } 1078 1079 if (Optional<PostStmt> PS = progPoint.getAs<PostStmt>()) { 1080 // FIXME: Assuming that BugReporter is a GRBugReporter is a layering 1081 // violation. 1082 const std::pair<const ProgramPointTag *, const ProgramPointTag *> &tags = 1083 cast<GRBugReporter>(BRC.getBugReporter()). 1084 getEngine().geteagerlyAssumeBinOpBifurcationTags(); 1085 1086 const ProgramPointTag *tag = PS->getTag(); 1087 if (tag == tags.first) 1088 return VisitTrueTest(cast<Expr>(PS->getStmt()), true, 1089 BRC, BR, N); 1090 if (tag == tags.second) 1091 return VisitTrueTest(cast<Expr>(PS->getStmt()), false, 1092 BRC, BR, N); 1093 1094 return 0; 1095 } 1096 1097 return 0; 1098} 1099 1100PathDiagnosticPiece * 1101ConditionBRVisitor::VisitTerminator(const Stmt *Term, 1102 const ExplodedNode *N, 1103 const CFGBlock *srcBlk, 1104 const CFGBlock *dstBlk, 1105 BugReport &R, 1106 BugReporterContext &BRC) { 1107 const Expr *Cond = 0; 1108 1109 switch (Term->getStmtClass()) { 1110 default: 1111 return 0; 1112 case Stmt::IfStmtClass: 1113 Cond = cast<IfStmt>(Term)->getCond(); 1114 break; 1115 case Stmt::ConditionalOperatorClass: 1116 Cond = cast<ConditionalOperator>(Term)->getCond(); 1117 break; 1118 } 1119 1120 assert(Cond); 1121 assert(srcBlk->succ_size() == 2); 1122 const bool tookTrue = *(srcBlk->succ_begin()) == dstBlk; 1123 return VisitTrueTest(Cond, tookTrue, BRC, R, N); 1124} 1125 1126PathDiagnosticPiece * 1127ConditionBRVisitor::VisitTrueTest(const Expr *Cond, 1128 bool tookTrue, 1129 BugReporterContext &BRC, 1130 BugReport &R, 1131 const ExplodedNode *N) { 1132 1133 const Expr *Ex = Cond; 1134 1135 while (true) { 1136 Ex = Ex->IgnoreParenCasts(); 1137 switch (Ex->getStmtClass()) { 1138 default: 1139 return 0; 1140 case Stmt::BinaryOperatorClass: 1141 return VisitTrueTest(Cond, cast<BinaryOperator>(Ex), tookTrue, BRC, 1142 R, N); 1143 case Stmt::DeclRefExprClass: 1144 return VisitTrueTest(Cond, cast<DeclRefExpr>(Ex), tookTrue, BRC, 1145 R, N); 1146 case Stmt::UnaryOperatorClass: { 1147 const UnaryOperator *UO = cast<UnaryOperator>(Ex); 1148 if (UO->getOpcode() == UO_LNot) { 1149 tookTrue = !tookTrue; 1150 Ex = UO->getSubExpr(); 1151 continue; 1152 } 1153 return 0; 1154 } 1155 } 1156 } 1157} 1158 1159bool ConditionBRVisitor::patternMatch(const Expr *Ex, raw_ostream &Out, 1160 BugReporterContext &BRC, 1161 BugReport &report, 1162 const ExplodedNode *N, 1163 Optional<bool> &prunable) { 1164 const Expr *OriginalExpr = Ex; 1165 Ex = Ex->IgnoreParenCasts(); 1166 1167 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Ex)) { 1168 const bool quotes = isa<VarDecl>(DR->getDecl()); 1169 if (quotes) { 1170 Out << '\''; 1171 const LocationContext *LCtx = N->getLocationContext(); 1172 const ProgramState *state = N->getState().getPtr(); 1173 if (const MemRegion *R = state->getLValue(cast<VarDecl>(DR->getDecl()), 1174 LCtx).getAsRegion()) { 1175 if (report.isInteresting(R)) 1176 prunable = false; 1177 else { 1178 const ProgramState *state = N->getState().getPtr(); 1179 SVal V = state->getSVal(R); 1180 if (report.isInteresting(V)) 1181 prunable = false; 1182 } 1183 } 1184 } 1185 Out << DR->getDecl()->getDeclName().getAsString(); 1186 if (quotes) 1187 Out << '\''; 1188 return quotes; 1189 } 1190 1191 if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(Ex)) { 1192 QualType OriginalTy = OriginalExpr->getType(); 1193 if (OriginalTy->isPointerType()) { 1194 if (IL->getValue() == 0) { 1195 Out << "null"; 1196 return false; 1197 } 1198 } 1199 else if (OriginalTy->isObjCObjectPointerType()) { 1200 if (IL->getValue() == 0) { 1201 Out << "nil"; 1202 return false; 1203 } 1204 } 1205 1206 Out << IL->getValue(); 1207 return false; 1208 } 1209 1210 return false; 1211} 1212 1213PathDiagnosticPiece * 1214ConditionBRVisitor::VisitTrueTest(const Expr *Cond, 1215 const BinaryOperator *BExpr, 1216 const bool tookTrue, 1217 BugReporterContext &BRC, 1218 BugReport &R, 1219 const ExplodedNode *N) { 1220 1221 bool shouldInvert = false; 1222 Optional<bool> shouldPrune; 1223 1224 SmallString<128> LhsString, RhsString; 1225 { 1226 llvm::raw_svector_ostream OutLHS(LhsString), OutRHS(RhsString); 1227 const bool isVarLHS = patternMatch(BExpr->getLHS(), OutLHS, BRC, R, N, 1228 shouldPrune); 1229 const bool isVarRHS = patternMatch(BExpr->getRHS(), OutRHS, BRC, R, N, 1230 shouldPrune); 1231 1232 shouldInvert = !isVarLHS && isVarRHS; 1233 } 1234 1235 BinaryOperator::Opcode Op = BExpr->getOpcode(); 1236 1237 if (BinaryOperator::isAssignmentOp(Op)) { 1238 // For assignment operators, all that we care about is that the LHS 1239 // evaluates to "true" or "false". 1240 return VisitConditionVariable(LhsString, BExpr->getLHS(), tookTrue, 1241 BRC, R, N); 1242 } 1243 1244 // For non-assignment operations, we require that we can understand 1245 // both the LHS and RHS. 1246 if (LhsString.empty() || RhsString.empty()) 1247 return 0; 1248 1249 // Should we invert the strings if the LHS is not a variable name? 1250 SmallString<256> buf; 1251 llvm::raw_svector_ostream Out(buf); 1252 Out << "Assuming " << (shouldInvert ? RhsString : LhsString) << " is "; 1253 1254 // Do we need to invert the opcode? 1255 if (shouldInvert) 1256 switch (Op) { 1257 default: break; 1258 case BO_LT: Op = BO_GT; break; 1259 case BO_GT: Op = BO_LT; break; 1260 case BO_LE: Op = BO_GE; break; 1261 case BO_GE: Op = BO_LE; break; 1262 } 1263 1264 if (!tookTrue) 1265 switch (Op) { 1266 case BO_EQ: Op = BO_NE; break; 1267 case BO_NE: Op = BO_EQ; break; 1268 case BO_LT: Op = BO_GE; break; 1269 case BO_GT: Op = BO_LE; break; 1270 case BO_LE: Op = BO_GT; break; 1271 case BO_GE: Op = BO_LT; break; 1272 default: 1273 return 0; 1274 } 1275 1276 switch (Op) { 1277 case BO_EQ: 1278 Out << "equal to "; 1279 break; 1280 case BO_NE: 1281 Out << "not equal to "; 1282 break; 1283 default: 1284 Out << BinaryOperator::getOpcodeStr(Op) << ' '; 1285 break; 1286 } 1287 1288 Out << (shouldInvert ? LhsString : RhsString); 1289 const LocationContext *LCtx = N->getLocationContext(); 1290 PathDiagnosticLocation Loc(Cond, BRC.getSourceManager(), LCtx); 1291 PathDiagnosticEventPiece *event = 1292 new PathDiagnosticEventPiece(Loc, Out.str()); 1293 if (shouldPrune.hasValue()) 1294 event->setPrunable(shouldPrune.getValue()); 1295 return event; 1296} 1297 1298PathDiagnosticPiece * 1299ConditionBRVisitor::VisitConditionVariable(StringRef LhsString, 1300 const Expr *CondVarExpr, 1301 const bool tookTrue, 1302 BugReporterContext &BRC, 1303 BugReport &report, 1304 const ExplodedNode *N) { 1305 // FIXME: If there's already a constraint tracker for this variable, 1306 // we shouldn't emit anything here (c.f. the double note in 1307 // test/Analysis/inlining/path-notes.c) 1308 SmallString<256> buf; 1309 llvm::raw_svector_ostream Out(buf); 1310 Out << "Assuming " << LhsString << " is "; 1311 1312 QualType Ty = CondVarExpr->getType(); 1313 1314 if (Ty->isPointerType()) 1315 Out << (tookTrue ? "not null" : "null"); 1316 else if (Ty->isObjCObjectPointerType()) 1317 Out << (tookTrue ? "not nil" : "nil"); 1318 else if (Ty->isBooleanType()) 1319 Out << (tookTrue ? "true" : "false"); 1320 else if (Ty->isIntegerType()) 1321 Out << (tookTrue ? "non-zero" : "zero"); 1322 else 1323 return 0; 1324 1325 const LocationContext *LCtx = N->getLocationContext(); 1326 PathDiagnosticLocation Loc(CondVarExpr, BRC.getSourceManager(), LCtx); 1327 PathDiagnosticEventPiece *event = 1328 new PathDiagnosticEventPiece(Loc, Out.str()); 1329 1330 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(CondVarExpr)) { 1331 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 1332 const ProgramState *state = N->getState().getPtr(); 1333 if (const MemRegion *R = state->getLValue(VD, LCtx).getAsRegion()) { 1334 if (report.isInteresting(R)) 1335 event->setPrunable(false); 1336 } 1337 } 1338 } 1339 1340 return event; 1341} 1342 1343PathDiagnosticPiece * 1344ConditionBRVisitor::VisitTrueTest(const Expr *Cond, 1345 const DeclRefExpr *DR, 1346 const bool tookTrue, 1347 BugReporterContext &BRC, 1348 BugReport &report, 1349 const ExplodedNode *N) { 1350 1351 const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl()); 1352 if (!VD) 1353 return 0; 1354 1355 SmallString<256> Buf; 1356 llvm::raw_svector_ostream Out(Buf); 1357 1358 Out << "Assuming '"; 1359 VD->getDeclName().printName(Out); 1360 Out << "' is "; 1361 1362 QualType VDTy = VD->getType(); 1363 1364 if (VDTy->isPointerType()) 1365 Out << (tookTrue ? "non-null" : "null"); 1366 else if (VDTy->isObjCObjectPointerType()) 1367 Out << (tookTrue ? "non-nil" : "nil"); 1368 else if (VDTy->isScalarType()) 1369 Out << (tookTrue ? "not equal to 0" : "0"); 1370 else 1371 return 0; 1372 1373 const LocationContext *LCtx = N->getLocationContext(); 1374 PathDiagnosticLocation Loc(Cond, BRC.getSourceManager(), LCtx); 1375 PathDiagnosticEventPiece *event = 1376 new PathDiagnosticEventPiece(Loc, Out.str()); 1377 1378 const ProgramState *state = N->getState().getPtr(); 1379 if (const MemRegion *R = state->getLValue(VD, LCtx).getAsRegion()) { 1380 if (report.isInteresting(R)) 1381 event->setPrunable(false); 1382 else { 1383 SVal V = state->getSVal(R); 1384 if (report.isInteresting(V)) 1385 event->setPrunable(false); 1386 } 1387 } 1388 return event; 1389} 1390 1391PathDiagnosticPiece * 1392LikelyFalsePositiveSuppressionBRVisitor::getEndPath(BugReporterContext &BRC, 1393 const ExplodedNode *N, 1394 BugReport &BR) { 1395 const Stmt *S = BR.getStmt(); 1396 if (!S) 1397 return 0; 1398 1399 // Here we suppress false positives coming from system macros. This list is 1400 // based on known issues. 1401 1402 // Skip reports within the sys/queue.h macros as we do not have the ability to 1403 // reason about data structure shapes. 1404 SourceManager &SM = BRC.getSourceManager(); 1405 SourceLocation Loc = S->getLocStart(); 1406 while (Loc.isMacroID()) { 1407 if (SM.isInSystemMacro(Loc) && 1408 (SM.getFilename(SM.getSpellingLoc(Loc)).endswith("sys/queue.h"))) { 1409 BR.markInvalid(getTag(), 0); 1410 return 0; 1411 } 1412 Loc = SM.getSpellingLoc(Loc); 1413 } 1414 1415 return 0; 1416} 1417 1418PathDiagnosticPiece * 1419UndefOrNullArgVisitor::VisitNode(const ExplodedNode *N, 1420 const ExplodedNode *PrevN, 1421 BugReporterContext &BRC, 1422 BugReport &BR) { 1423 1424 ProgramStateRef State = N->getState(); 1425 ProgramPoint ProgLoc = N->getLocation(); 1426 1427 // We are only interested in visiting CallEnter nodes. 1428 Optional<CallEnter> CEnter = ProgLoc.getAs<CallEnter>(); 1429 if (!CEnter) 1430 return 0; 1431 1432 // Check if one of the arguments is the region the visitor is tracking. 1433 CallEventManager &CEMgr = BRC.getStateManager().getCallEventManager(); 1434 CallEventRef<> Call = CEMgr.getCaller(CEnter->getCalleeContext(), State); 1435 unsigned Idx = 0; 1436 for (CallEvent::param_iterator I = Call->param_begin(), 1437 E = Call->param_end(); I != E; ++I, ++Idx) { 1438 const MemRegion *ArgReg = Call->getArgSVal(Idx).getAsRegion(); 1439 1440 // Are we tracking the argument or its subregion? 1441 if ( !ArgReg || (ArgReg != R && !R->isSubRegionOf(ArgReg->StripCasts()))) 1442 continue; 1443 1444 // Check the function parameter type. 1445 const ParmVarDecl *ParamDecl = *I; 1446 assert(ParamDecl && "Formal parameter has no decl?"); 1447 QualType T = ParamDecl->getType(); 1448 1449 if (!(T->isAnyPointerType() || T->isReferenceType())) { 1450 // Function can only change the value passed in by address. 1451 continue; 1452 } 1453 1454 // If it is a const pointer value, the function does not intend to 1455 // change the value. 1456 if (T->getPointeeType().isConstQualified()) 1457 continue; 1458 1459 // Mark the call site (LocationContext) as interesting if the value of the 1460 // argument is undefined or '0'/'NULL'. 1461 SVal BoundVal = State->getSVal(R); 1462 if (BoundVal.isUndef() || BoundVal.isZeroConstant()) { 1463 BR.markInteresting(CEnter->getCalleeContext()); 1464 return 0; 1465 } 1466 } 1467 return 0; 1468} 1469