| // BugReporterVisitors.cpp - Helpers for reporting bugs -----------*- C++ -*--// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines a set of BugReporter "visitors" which can be used to |
| // enhance the diagnostics reported for a bug. |
| // |
| //===----------------------------------------------------------------------===// |
| #include "clang/StaticAnalyzer/Core/BugReporter/BugReporterVisitor.h" |
| #include "clang/AST/Expr.h" |
| #include "clang/AST/ExprObjC.h" |
| #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h" |
| #include "clang/StaticAnalyzer/Core/BugReporter/PathDiagnostic.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" |
| #include "llvm/ADT/SmallString.h" |
| #include "llvm/ADT/StringExtras.h" |
| #include "llvm/Support/raw_ostream.h" |
| |
| using namespace clang; |
| using namespace ento; |
| |
| using llvm::FoldingSetNodeID; |
| |
| //===----------------------------------------------------------------------===// |
| // Utility functions. |
| //===----------------------------------------------------------------------===// |
| |
| bool bugreporter::isDeclRefExprToReference(const Expr *E) { |
| if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) { |
| return DRE->getDecl()->getType()->isReferenceType(); |
| } |
| return false; |
| } |
| |
| const Expr *bugreporter::getDerefExpr(const Stmt *S) { |
| // Pattern match for a few useful cases: |
| // a[0], p->f, *p |
| const Expr *E = dyn_cast<Expr>(S); |
| if (!E) |
| return 0; |
| E = E->IgnoreParenCasts(); |
| |
| while (true) { |
| if (const BinaryOperator *B = dyn_cast<BinaryOperator>(E)) { |
| assert(B->isAssignmentOp()); |
| E = B->getLHS()->IgnoreParenCasts(); |
| continue; |
| } |
| else if (const UnaryOperator *U = dyn_cast<UnaryOperator>(E)) { |
| if (U->getOpcode() == UO_Deref) |
| return U->getSubExpr()->IgnoreParenCasts(); |
| } |
| else if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) { |
| if (ME->isArrow() || isDeclRefExprToReference(ME->getBase())) { |
| return ME->getBase()->IgnoreParenCasts(); |
| } else { |
| // If we have a member expr with a dot, the base must have been |
| // dereferenced. |
| return getDerefExpr(ME->getBase()); |
| } |
| } |
| else if (const ObjCIvarRefExpr *IvarRef = dyn_cast<ObjCIvarRefExpr>(E)) { |
| return IvarRef->getBase()->IgnoreParenCasts(); |
| } |
| else if (const ArraySubscriptExpr *AE = dyn_cast<ArraySubscriptExpr>(E)) { |
| return AE->getBase(); |
| } |
| else if (isDeclRefExprToReference(E)) { |
| return E; |
| } |
| break; |
| } |
| |
| return NULL; |
| } |
| |
| const Stmt *bugreporter::GetDenomExpr(const ExplodedNode *N) { |
| const Stmt *S = N->getLocationAs<PreStmt>()->getStmt(); |
| if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(S)) |
| return BE->getRHS(); |
| return NULL; |
| } |
| |
| const Stmt *bugreporter::GetRetValExpr(const ExplodedNode *N) { |
| const Stmt *S = N->getLocationAs<PostStmt>()->getStmt(); |
| if (const ReturnStmt *RS = dyn_cast<ReturnStmt>(S)) |
| return RS->getRetValue(); |
| return NULL; |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Definitions for bug reporter visitors. |
| //===----------------------------------------------------------------------===// |
| |
| PathDiagnosticPiece* |
| BugReporterVisitor::getEndPath(BugReporterContext &BRC, |
| const ExplodedNode *EndPathNode, |
| BugReport &BR) { |
| return 0; |
| } |
| |
| PathDiagnosticPiece* |
| BugReporterVisitor::getDefaultEndPath(BugReporterContext &BRC, |
| const ExplodedNode *EndPathNode, |
| BugReport &BR) { |
| PathDiagnosticLocation L = |
| PathDiagnosticLocation::createEndOfPath(EndPathNode,BRC.getSourceManager()); |
| |
| BugReport::ranges_iterator Beg, End; |
| std::tie(Beg, End) = BR.getRanges(); |
| |
| // Only add the statement itself as a range if we didn't specify any |
| // special ranges for this report. |
| PathDiagnosticPiece *P = new PathDiagnosticEventPiece(L, |
| BR.getDescription(), |
| Beg == End); |
| for (; Beg != End; ++Beg) |
| P->addRange(*Beg); |
| |
| return P; |
| } |
| |
| |
| namespace { |
| /// Emits an extra note at the return statement of an interesting stack frame. |
| /// |
| /// The returned value is marked as an interesting value, and if it's null, |
| /// adds a visitor to track where it became null. |
| /// |
| /// This visitor is intended to be used when another visitor discovers that an |
| /// interesting value comes from an inlined function call. |
| class ReturnVisitor : public BugReporterVisitorImpl<ReturnVisitor> { |
| const StackFrameContext *StackFrame; |
| enum { |
| Initial, |
| MaybeUnsuppress, |
| Satisfied |
| } Mode; |
| |
| bool EnableNullFPSuppression; |
| |
| public: |
| ReturnVisitor(const StackFrameContext *Frame, bool Suppressed) |
| : StackFrame(Frame), Mode(Initial), EnableNullFPSuppression(Suppressed) {} |
| |
| static void *getTag() { |
| static int Tag = 0; |
| return static_cast<void *>(&Tag); |
| } |
| |
| void Profile(llvm::FoldingSetNodeID &ID) const override { |
| ID.AddPointer(ReturnVisitor::getTag()); |
| ID.AddPointer(StackFrame); |
| ID.AddBoolean(EnableNullFPSuppression); |
| } |
| |
| /// Adds a ReturnVisitor if the given statement represents a call that was |
| /// inlined. |
| /// |
| /// This will search back through the ExplodedGraph, starting from the given |
| /// node, looking for when the given statement was processed. If it turns out |
| /// the statement is a call that was inlined, we add the visitor to the |
| /// bug report, so it can print a note later. |
| static void addVisitorIfNecessary(const ExplodedNode *Node, const Stmt *S, |
| BugReport &BR, |
| bool InEnableNullFPSuppression) { |
| if (!CallEvent::isCallStmt(S)) |
| return; |
| |
| // First, find when we processed the statement. |
| do { |
| if (Optional<CallExitEnd> CEE = Node->getLocationAs<CallExitEnd>()) |
| if (CEE->getCalleeContext()->getCallSite() == S) |
| break; |
| if (Optional<StmtPoint> SP = Node->getLocationAs<StmtPoint>()) |
| if (SP->getStmt() == S) |
| break; |
| |
| Node = Node->getFirstPred(); |
| } while (Node); |
| |
| // Next, step over any post-statement checks. |
| while (Node && Node->getLocation().getAs<PostStmt>()) |
| Node = Node->getFirstPred(); |
| if (!Node) |
| return; |
| |
| // Finally, see if we inlined the call. |
| Optional<CallExitEnd> CEE = Node->getLocationAs<CallExitEnd>(); |
| if (!CEE) |
| return; |
| |
| const StackFrameContext *CalleeContext = CEE->getCalleeContext(); |
| if (CalleeContext->getCallSite() != S) |
| return; |
| |
| // Check the return value. |
| ProgramStateRef State = Node->getState(); |
| SVal RetVal = State->getSVal(S, Node->getLocationContext()); |
| |
| // Handle cases where a reference is returned and then immediately used. |
| if (cast<Expr>(S)->isGLValue()) |
| if (Optional<Loc> LValue = RetVal.getAs<Loc>()) |
| RetVal = State->getSVal(*LValue); |
| |
| // See if the return value is NULL. If so, suppress the report. |
| SubEngine *Eng = State->getStateManager().getOwningEngine(); |
| assert(Eng && "Cannot file a bug report without an owning engine"); |
| AnalyzerOptions &Options = Eng->getAnalysisManager().options; |
| |
| bool EnableNullFPSuppression = false; |
| if (InEnableNullFPSuppression && Options.shouldSuppressNullReturnPaths()) |
| if (Optional<Loc> RetLoc = RetVal.getAs<Loc>()) |
| EnableNullFPSuppression = State->isNull(*RetLoc).isConstrainedTrue(); |
| |
| BR.markInteresting(CalleeContext); |
| BR.addVisitor(new ReturnVisitor(CalleeContext, EnableNullFPSuppression)); |
| } |
| |
| /// Returns true if any counter-suppression heuristics are enabled for |
| /// ReturnVisitor. |
| static bool hasCounterSuppression(AnalyzerOptions &Options) { |
| return Options.shouldAvoidSuppressingNullArgumentPaths(); |
| } |
| |
| PathDiagnosticPiece *visitNodeInitial(const ExplodedNode *N, |
| const ExplodedNode *PrevN, |
| BugReporterContext &BRC, |
| BugReport &BR) { |
| // Only print a message at the interesting return statement. |
| if (N->getLocationContext() != StackFrame) |
| return 0; |
| |
| Optional<StmtPoint> SP = N->getLocationAs<StmtPoint>(); |
| if (!SP) |
| return 0; |
| |
| const ReturnStmt *Ret = dyn_cast<ReturnStmt>(SP->getStmt()); |
| if (!Ret) |
| return 0; |
| |
| // Okay, we're at the right return statement, but do we have the return |
| // value available? |
| ProgramStateRef State = N->getState(); |
| SVal V = State->getSVal(Ret, StackFrame); |
| if (V.isUnknownOrUndef()) |
| return 0; |
| |
| // Don't print any more notes after this one. |
| Mode = Satisfied; |
| |
| const Expr *RetE = Ret->getRetValue(); |
| assert(RetE && "Tracking a return value for a void function"); |
| |
| // Handle cases where a reference is returned and then immediately used. |
| Optional<Loc> LValue; |
| if (RetE->isGLValue()) { |
| if ((LValue = V.getAs<Loc>())) { |
| SVal RValue = State->getRawSVal(*LValue, RetE->getType()); |
| if (RValue.getAs<DefinedSVal>()) |
| V = RValue; |
| } |
| } |
| |
| // Ignore aggregate rvalues. |
| if (V.getAs<nonloc::LazyCompoundVal>() || |
| V.getAs<nonloc::CompoundVal>()) |
| return 0; |
| |
| RetE = RetE->IgnoreParenCasts(); |
| |
| // If we can't prove the return value is 0, just mark it interesting, and |
| // make sure to track it into any further inner functions. |
| if (!State->isNull(V).isConstrainedTrue()) { |
| BR.markInteresting(V); |
| ReturnVisitor::addVisitorIfNecessary(N, RetE, BR, |
| EnableNullFPSuppression); |
| return 0; |
| } |
| |
| // If we're returning 0, we should track where that 0 came from. |
| bugreporter::trackNullOrUndefValue(N, RetE, BR, /*IsArg*/ false, |
| EnableNullFPSuppression); |
| |
| // Build an appropriate message based on the return value. |
| SmallString<64> Msg; |
| llvm::raw_svector_ostream Out(Msg); |
| |
| if (V.getAs<Loc>()) { |
| // If we have counter-suppression enabled, make sure we keep visiting |
| // future nodes. We want to emit a path note as well, in case |
| // the report is resurrected as valid later on. |
| ExprEngine &Eng = BRC.getBugReporter().getEngine(); |
| AnalyzerOptions &Options = Eng.getAnalysisManager().options; |
| if (EnableNullFPSuppression && hasCounterSuppression(Options)) |
| Mode = MaybeUnsuppress; |
| |
| if (RetE->getType()->isObjCObjectPointerType()) |
| Out << "Returning nil"; |
| else |
| Out << "Returning null pointer"; |
| } else { |
| Out << "Returning zero"; |
| } |
| |
| if (LValue) { |
| if (const MemRegion *MR = LValue->getAsRegion()) { |
| if (MR->canPrintPretty()) { |
| Out << " (reference to "; |
| MR->printPretty(Out); |
| Out << ")"; |
| } |
| } |
| } else { |
| // FIXME: We should have a more generalized location printing mechanism. |
| if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetE)) |
| if (const DeclaratorDecl *DD = dyn_cast<DeclaratorDecl>(DR->getDecl())) |
| Out << " (loaded from '" << *DD << "')"; |
| } |
| |
| PathDiagnosticLocation L(Ret, BRC.getSourceManager(), StackFrame); |
| return new PathDiagnosticEventPiece(L, Out.str()); |
| } |
| |
| PathDiagnosticPiece *visitNodeMaybeUnsuppress(const ExplodedNode *N, |
| const ExplodedNode *PrevN, |
| BugReporterContext &BRC, |
| BugReport &BR) { |
| #ifndef NDEBUG |
| ExprEngine &Eng = BRC.getBugReporter().getEngine(); |
| AnalyzerOptions &Options = Eng.getAnalysisManager().options; |
| assert(hasCounterSuppression(Options)); |
| #endif |
| |
| // Are we at the entry node for this call? |
| Optional<CallEnter> CE = N->getLocationAs<CallEnter>(); |
| if (!CE) |
| return 0; |
| |
| if (CE->getCalleeContext() != StackFrame) |
| return 0; |
| |
| Mode = Satisfied; |
| |
| // Don't automatically suppress a report if one of the arguments is |
| // known to be a null pointer. Instead, start tracking /that/ null |
| // value back to its origin. |
| ProgramStateManager &StateMgr = BRC.getStateManager(); |
| CallEventManager &CallMgr = StateMgr.getCallEventManager(); |
| |
| ProgramStateRef State = N->getState(); |
| CallEventRef<> Call = CallMgr.getCaller(StackFrame, State); |
| for (unsigned I = 0, E = Call->getNumArgs(); I != E; ++I) { |
| Optional<Loc> ArgV = Call->getArgSVal(I).getAs<Loc>(); |
| if (!ArgV) |
| continue; |
| |
| const Expr *ArgE = Call->getArgExpr(I); |
| if (!ArgE) |
| continue; |
| |
| // Is it possible for this argument to be non-null? |
| if (!State->isNull(*ArgV).isConstrainedTrue()) |
| continue; |
| |
| if (bugreporter::trackNullOrUndefValue(N, ArgE, BR, /*IsArg=*/true, |
| EnableNullFPSuppression)) |
| BR.removeInvalidation(ReturnVisitor::getTag(), StackFrame); |
| |
| // If we /can't/ track the null pointer, we should err on the side of |
| // false negatives, and continue towards marking this report invalid. |
| // (We will still look at the other arguments, though.) |
| } |
| |
| return 0; |
| } |
| |
| PathDiagnosticPiece *VisitNode(const ExplodedNode *N, |
| const ExplodedNode *PrevN, |
| BugReporterContext &BRC, |
| BugReport &BR) override { |
| switch (Mode) { |
| case Initial: |
| return visitNodeInitial(N, PrevN, BRC, BR); |
| case MaybeUnsuppress: |
| return visitNodeMaybeUnsuppress(N, PrevN, BRC, BR); |
| case Satisfied: |
| return 0; |
| } |
| |
| llvm_unreachable("Invalid visit mode!"); |
| } |
| |
| PathDiagnosticPiece *getEndPath(BugReporterContext &BRC, |
| const ExplodedNode *N, |
| BugReport &BR) override { |
| if (EnableNullFPSuppression) |
| BR.markInvalid(ReturnVisitor::getTag(), StackFrame); |
| return 0; |
| } |
| }; |
| } // end anonymous namespace |
| |
| |
| void FindLastStoreBRVisitor ::Profile(llvm::FoldingSetNodeID &ID) const { |
| static int tag = 0; |
| ID.AddPointer(&tag); |
| ID.AddPointer(R); |
| ID.Add(V); |
| ID.AddBoolean(EnableNullFPSuppression); |
| } |
| |
| /// Returns true if \p N represents the DeclStmt declaring and initializing |
| /// \p VR. |
| static bool isInitializationOfVar(const ExplodedNode *N, const VarRegion *VR) { |
| Optional<PostStmt> P = N->getLocationAs<PostStmt>(); |
| if (!P) |
| return false; |
| |
| const DeclStmt *DS = P->getStmtAs<DeclStmt>(); |
| if (!DS) |
| return false; |
| |
| if (DS->getSingleDecl() != VR->getDecl()) |
| return false; |
| |
| const MemSpaceRegion *VarSpace = VR->getMemorySpace(); |
| const StackSpaceRegion *FrameSpace = dyn_cast<StackSpaceRegion>(VarSpace); |
| if (!FrameSpace) { |
| // If we ever directly evaluate global DeclStmts, this assertion will be |
| // invalid, but this still seems preferable to silently accepting an |
| // initialization that may be for a path-sensitive variable. |
| assert(VR->getDecl()->isStaticLocal() && "non-static stackless VarRegion"); |
| return true; |
| } |
| |
| assert(VR->getDecl()->hasLocalStorage()); |
| const LocationContext *LCtx = N->getLocationContext(); |
| return FrameSpace->getStackFrame() == LCtx->getCurrentStackFrame(); |
| } |
| |
| PathDiagnosticPiece *FindLastStoreBRVisitor::VisitNode(const ExplodedNode *Succ, |
| const ExplodedNode *Pred, |
| BugReporterContext &BRC, |
| BugReport &BR) { |
| |
| if (Satisfied) |
| return NULL; |
| |
| const ExplodedNode *StoreSite = 0; |
| const Expr *InitE = 0; |
| bool IsParam = false; |
| |
| // First see if we reached the declaration of the region. |
| if (const VarRegion *VR = dyn_cast<VarRegion>(R)) { |
| if (isInitializationOfVar(Pred, VR)) { |
| StoreSite = Pred; |
| InitE = VR->getDecl()->getInit(); |
| } |
| } |
| |
| // If this is a post initializer expression, initializing the region, we |
| // should track the initializer expression. |
| if (Optional<PostInitializer> PIP = Pred->getLocationAs<PostInitializer>()) { |
| const MemRegion *FieldReg = (const MemRegion *)PIP->getLocationValue(); |
| if (FieldReg && FieldReg == R) { |
| StoreSite = Pred; |
| InitE = PIP->getInitializer()->getInit(); |
| } |
| } |
| |
| // Otherwise, see if this is the store site: |
| // (1) Succ has this binding and Pred does not, i.e. this is |
| // where the binding first occurred. |
| // (2) Succ has this binding and is a PostStore node for this region, i.e. |
| // the same binding was re-assigned here. |
| if (!StoreSite) { |
| if (Succ->getState()->getSVal(R) != V) |
| return NULL; |
| |
| if (Pred->getState()->getSVal(R) == V) { |
| Optional<PostStore> PS = Succ->getLocationAs<PostStore>(); |
| if (!PS || PS->getLocationValue() != R) |
| return NULL; |
| } |
| |
| StoreSite = Succ; |
| |
| // If this is an assignment expression, we can track the value |
| // being assigned. |
| if (Optional<PostStmt> P = Succ->getLocationAs<PostStmt>()) |
| if (const BinaryOperator *BO = P->getStmtAs<BinaryOperator>()) |
| if (BO->isAssignmentOp()) |
| InitE = BO->getRHS(); |
| |
| // If this is a call entry, the variable should be a parameter. |
| // FIXME: Handle CXXThisRegion as well. (This is not a priority because |
| // 'this' should never be NULL, but this visitor isn't just for NULL and |
| // UndefinedVal.) |
| if (Optional<CallEnter> CE = Succ->getLocationAs<CallEnter>()) { |
| if (const VarRegion *VR = dyn_cast<VarRegion>(R)) { |
| const ParmVarDecl *Param = cast<ParmVarDecl>(VR->getDecl()); |
| |
| ProgramStateManager &StateMgr = BRC.getStateManager(); |
| CallEventManager &CallMgr = StateMgr.getCallEventManager(); |
| |
| CallEventRef<> Call = CallMgr.getCaller(CE->getCalleeContext(), |
| Succ->getState()); |
| InitE = Call->getArgExpr(Param->getFunctionScopeIndex()); |
| IsParam = true; |
| } |
| } |
| |
| // If this is a CXXTempObjectRegion, the Expr responsible for its creation |
| // is wrapped inside of it. |
| if (const CXXTempObjectRegion *TmpR = dyn_cast<CXXTempObjectRegion>(R)) |
| InitE = TmpR->getExpr(); |
| } |
| |
| if (!StoreSite) |
| return NULL; |
| Satisfied = true; |
| |
| // If we have an expression that provided the value, try to track where it |
| // came from. |
| if (InitE) { |
| if (V.isUndef() || |
| V.getAs<loc::ConcreteInt>() || V.getAs<nonloc::ConcreteInt>()) { |
| if (!IsParam) |
| InitE = InitE->IgnoreParenCasts(); |
| bugreporter::trackNullOrUndefValue(StoreSite, InitE, BR, IsParam, |
| EnableNullFPSuppression); |
| } else { |
| ReturnVisitor::addVisitorIfNecessary(StoreSite, InitE->IgnoreParenCasts(), |
| BR, EnableNullFPSuppression); |
| } |
| } |
| |
| // Okay, we've found the binding. Emit an appropriate message. |
| SmallString<256> sbuf; |
| llvm::raw_svector_ostream os(sbuf); |
| |
| if (Optional<PostStmt> PS = StoreSite->getLocationAs<PostStmt>()) { |
| const Stmt *S = PS->getStmt(); |
| const char *action = 0; |
| const DeclStmt *DS = dyn_cast<DeclStmt>(S); |
| const VarRegion *VR = dyn_cast<VarRegion>(R); |
| |
| if (DS) { |
| action = R->canPrintPretty() ? "initialized to " : |
| "Initializing to "; |
| } else if (isa<BlockExpr>(S)) { |
| action = R->canPrintPretty() ? "captured by block as " : |
| "Captured by block as "; |
| if (VR) { |
| // See if we can get the BlockVarRegion. |
| ProgramStateRef State = StoreSite->getState(); |
| SVal V = State->getSVal(S, PS->getLocationContext()); |
| if (const BlockDataRegion *BDR = |
| dyn_cast_or_null<BlockDataRegion>(V.getAsRegion())) { |
| if (const VarRegion *OriginalR = BDR->getOriginalRegion(VR)) { |
| if (Optional<KnownSVal> KV = |
| State->getSVal(OriginalR).getAs<KnownSVal>()) |
| BR.addVisitor(new FindLastStoreBRVisitor(*KV, OriginalR, |
| EnableNullFPSuppression)); |
| } |
| } |
| } |
| } |
| |
| if (action) { |
| if (R->canPrintPretty()) { |
| R->printPretty(os); |
| os << " "; |
| } |
| |
| if (V.getAs<loc::ConcreteInt>()) { |
| bool b = false; |
| if (R->isBoundable()) { |
| if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) { |
| if (TR->getValueType()->isObjCObjectPointerType()) { |
| os << action << "nil"; |
| b = true; |
| } |
| } |
| } |
| |
| if (!b) |
| os << action << "a null pointer value"; |
| } else if (Optional<nonloc::ConcreteInt> CVal = |
| V.getAs<nonloc::ConcreteInt>()) { |
| os << action << CVal->getValue(); |
| } |
| else if (DS) { |
| if (V.isUndef()) { |
| if (isa<VarRegion>(R)) { |
| const VarDecl *VD = cast<VarDecl>(DS->getSingleDecl()); |
| if (VD->getInit()) { |
| os << (R->canPrintPretty() ? "initialized" : "Initializing") |
| << " to a garbage value"; |
| } else { |
| os << (R->canPrintPretty() ? "declared" : "Declaring") |
| << " without an initial value"; |
| } |
| } |
| } |
| else { |
| os << (R->canPrintPretty() ? "initialized" : "Initialized") |
| << " here"; |
| } |
| } |
| } |
| } else if (StoreSite->getLocation().getAs<CallEnter>()) { |
| if (const VarRegion *VR = dyn_cast<VarRegion>(R)) { |
| const ParmVarDecl *Param = cast<ParmVarDecl>(VR->getDecl()); |
| |
| os << "Passing "; |
| |
| if (V.getAs<loc::ConcreteInt>()) { |
| if (Param->getType()->isObjCObjectPointerType()) |
| os << "nil object reference"; |
| else |
| os << "null pointer value"; |
| } else if (V.isUndef()) { |
| os << "uninitialized value"; |
| } else if (Optional<nonloc::ConcreteInt> CI = |
| V.getAs<nonloc::ConcreteInt>()) { |
| os << "the value " << CI->getValue(); |
| } else { |
| os << "value"; |
| } |
| |
| // Printed parameter indexes are 1-based, not 0-based. |
| unsigned Idx = Param->getFunctionScopeIndex() + 1; |
| os << " via " << Idx << llvm::getOrdinalSuffix(Idx) << " parameter"; |
| if (R->canPrintPretty()) { |
| os << " "; |
| R->printPretty(os); |
| } |
| } |
| } |
| |
| if (os.str().empty()) { |
| if (V.getAs<loc::ConcreteInt>()) { |
| bool b = false; |
| if (R->isBoundable()) { |
| if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) { |
| if (TR->getValueType()->isObjCObjectPointerType()) { |
| os << "nil object reference stored"; |
| b = true; |
| } |
| } |
| } |
| if (!b) { |
| if (R->canPrintPretty()) |
| os << "Null pointer value stored"; |
| else |
| os << "Storing null pointer value"; |
| } |
| |
| } else if (V.isUndef()) { |
| if (R->canPrintPretty()) |
| os << "Uninitialized value stored"; |
| else |
| os << "Storing uninitialized value"; |
| |
| } else if (Optional<nonloc::ConcreteInt> CV = |
| V.getAs<nonloc::ConcreteInt>()) { |
| if (R->canPrintPretty()) |
| os << "The value " << CV->getValue() << " is assigned"; |
| else |
| os << "Assigning " << CV->getValue(); |
| |
| } else { |
| if (R->canPrintPretty()) |
| os << "Value assigned"; |
| else |
| os << "Assigning value"; |
| } |
| |
| if (R->canPrintPretty()) { |
| os << " to "; |
| R->printPretty(os); |
| } |
| } |
| |
| // Construct a new PathDiagnosticPiece. |
| ProgramPoint P = StoreSite->getLocation(); |
| PathDiagnosticLocation L; |
| if (P.getAs<CallEnter>() && InitE) |
| L = PathDiagnosticLocation(InitE, BRC.getSourceManager(), |
| P.getLocationContext()); |
| |
| if (!L.isValid() || !L.asLocation().isValid()) |
| L = PathDiagnosticLocation::create(P, BRC.getSourceManager()); |
| |
| if (!L.isValid() || !L.asLocation().isValid()) |
| return NULL; |
| |
| return new PathDiagnosticEventPiece(L, os.str()); |
| } |
| |
| void TrackConstraintBRVisitor::Profile(llvm::FoldingSetNodeID &ID) const { |
| static int tag = 0; |
| ID.AddPointer(&tag); |
| ID.AddBoolean(Assumption); |
| ID.Add(Constraint); |
| } |
| |
| /// Return the tag associated with this visitor. This tag will be used |
| /// to make all PathDiagnosticPieces created by this visitor. |
| const char *TrackConstraintBRVisitor::getTag() { |
| return "TrackConstraintBRVisitor"; |
| } |
| |
| bool TrackConstraintBRVisitor::isUnderconstrained(const ExplodedNode *N) const { |
| if (IsZeroCheck) |
| return N->getState()->isNull(Constraint).isUnderconstrained(); |
| return N->getState()->assume(Constraint, !Assumption); |
| } |
| |
| PathDiagnosticPiece * |
| TrackConstraintBRVisitor::VisitNode(const ExplodedNode *N, |
| const ExplodedNode *PrevN, |
| BugReporterContext &BRC, |
| BugReport &BR) { |
| if (IsSatisfied) |
| return NULL; |
| |
| // Start tracking after we see the first state in which the value is |
| // constrained. |
| if (!IsTrackingTurnedOn) |
| if (!isUnderconstrained(N)) |
| IsTrackingTurnedOn = true; |
| if (!IsTrackingTurnedOn) |
| return 0; |
| |
| // Check if in the previous state it was feasible for this constraint |
| // to *not* be true. |
| if (isUnderconstrained(PrevN)) { |
| |
| IsSatisfied = true; |
| |
| // As a sanity check, make sure that the negation of the constraint |
| // was infeasible in the current state. If it is feasible, we somehow |
| // missed the transition point. |
| assert(!isUnderconstrained(N)); |
| |
| // We found the transition point for the constraint. We now need to |
| // pretty-print the constraint. (work-in-progress) |
| SmallString<64> sbuf; |
| llvm::raw_svector_ostream os(sbuf); |
| |
| if (Constraint.getAs<Loc>()) { |
| os << "Assuming pointer value is "; |
| os << (Assumption ? "non-null" : "null"); |
| } |
| |
| if (os.str().empty()) |
| return NULL; |
| |
| // Construct a new PathDiagnosticPiece. |
| ProgramPoint P = N->getLocation(); |
| PathDiagnosticLocation L = |
| PathDiagnosticLocation::create(P, BRC.getSourceManager()); |
| if (!L.isValid()) |
| return NULL; |
| |
| PathDiagnosticEventPiece *X = new PathDiagnosticEventPiece(L, os.str()); |
| X->setTag(getTag()); |
| return X; |
| } |
| |
| return NULL; |
| } |
| |
| SuppressInlineDefensiveChecksVisitor:: |
| SuppressInlineDefensiveChecksVisitor(DefinedSVal Value, const ExplodedNode *N) |
| : V(Value), IsSatisfied(false), IsTrackingTurnedOn(false) { |
| |
| // Check if the visitor is disabled. |
| SubEngine *Eng = N->getState()->getStateManager().getOwningEngine(); |
| assert(Eng && "Cannot file a bug report without an owning engine"); |
| AnalyzerOptions &Options = Eng->getAnalysisManager().options; |
| if (!Options.shouldSuppressInlinedDefensiveChecks()) |
| IsSatisfied = true; |
| |
| assert(N->getState()->isNull(V).isConstrainedTrue() && |
| "The visitor only tracks the cases where V is constrained to 0"); |
| } |
| |
| void SuppressInlineDefensiveChecksVisitor::Profile(FoldingSetNodeID &ID) const { |
| static int id = 0; |
| ID.AddPointer(&id); |
| ID.Add(V); |
| } |
| |
| const char *SuppressInlineDefensiveChecksVisitor::getTag() { |
| return "IDCVisitor"; |
| } |
| |
| PathDiagnosticPiece * |
| SuppressInlineDefensiveChecksVisitor::VisitNode(const ExplodedNode *Succ, |
| const ExplodedNode *Pred, |
| BugReporterContext &BRC, |
| BugReport &BR) { |
| if (IsSatisfied) |
| return 0; |
| |
| // Start tracking after we see the first state in which the value is null. |
| if (!IsTrackingTurnedOn) |
| if (Succ->getState()->isNull(V).isConstrainedTrue()) |
| IsTrackingTurnedOn = true; |
| if (!IsTrackingTurnedOn) |
| return 0; |
| |
| // Check if in the previous state it was feasible for this value |
| // to *not* be null. |
| if (!Pred->getState()->isNull(V).isConstrainedTrue()) { |
| IsSatisfied = true; |
| |
| assert(Succ->getState()->isNull(V).isConstrainedTrue()); |
| |
| // Check if this is inlined defensive checks. |
| const LocationContext *CurLC =Succ->getLocationContext(); |
| const LocationContext *ReportLC = BR.getErrorNode()->getLocationContext(); |
| if (CurLC != ReportLC && !CurLC->isParentOf(ReportLC)) |
| BR.markInvalid("Suppress IDC", CurLC); |
| } |
| return 0; |
| } |
| |
| static const MemRegion *getLocationRegionIfReference(const Expr *E, |
| const ExplodedNode *N) { |
| if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(E)) { |
| if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { |
| if (!VD->getType()->isReferenceType()) |
| return 0; |
| ProgramStateManager &StateMgr = N->getState()->getStateManager(); |
| MemRegionManager &MRMgr = StateMgr.getRegionManager(); |
| return MRMgr.getVarRegion(VD, N->getLocationContext()); |
| } |
| } |
| |
| // FIXME: This does not handle other kinds of null references, |
| // for example, references from FieldRegions: |
| // struct Wrapper { int &ref; }; |
| // Wrapper w = { *(int *)0 }; |
| // w.ref = 1; |
| |
| return 0; |
| } |
| |
| static const Expr *peelOffOuterExpr(const Expr *Ex, |
| const ExplodedNode *N) { |
| Ex = Ex->IgnoreParenCasts(); |
| if (const ExprWithCleanups *EWC = dyn_cast<ExprWithCleanups>(Ex)) |
| return peelOffOuterExpr(EWC->getSubExpr(), N); |
| if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(Ex)) |
| return peelOffOuterExpr(OVE->getSourceExpr(), N); |
| |
| // Peel off the ternary operator. |
| if (const ConditionalOperator *CO = dyn_cast<ConditionalOperator>(Ex)) { |
| // Find a node where the branching occurred and find out which branch |
| // we took (true/false) by looking at the ExplodedGraph. |
| const ExplodedNode *NI = N; |
| do { |
| ProgramPoint ProgPoint = NI->getLocation(); |
| if (Optional<BlockEdge> BE = ProgPoint.getAs<BlockEdge>()) { |
| const CFGBlock *srcBlk = BE->getSrc(); |
| if (const Stmt *term = srcBlk->getTerminator()) { |
| if (term == CO) { |
| bool TookTrueBranch = (*(srcBlk->succ_begin()) == BE->getDst()); |
| if (TookTrueBranch) |
| return peelOffOuterExpr(CO->getTrueExpr(), N); |
| else |
| return peelOffOuterExpr(CO->getFalseExpr(), N); |
| } |
| } |
| } |
| NI = NI->getFirstPred(); |
| } while (NI); |
| } |
| return Ex; |
| } |
| |
| bool bugreporter::trackNullOrUndefValue(const ExplodedNode *N, |
| const Stmt *S, |
| BugReport &report, bool IsArg, |
| bool EnableNullFPSuppression) { |
| if (!S || !N) |
| return false; |
| |
| if (const Expr *Ex = dyn_cast<Expr>(S)) { |
| Ex = Ex->IgnoreParenCasts(); |
| const Expr *PeeledEx = peelOffOuterExpr(Ex, N); |
| if (Ex != PeeledEx) |
| S = PeeledEx; |
| } |
| |
| const Expr *Inner = 0; |
| if (const Expr *Ex = dyn_cast<Expr>(S)) { |
| Ex = Ex->IgnoreParenCasts(); |
| if (ExplodedGraph::isInterestingLValueExpr(Ex) || CallEvent::isCallStmt(Ex)) |
| Inner = Ex; |
| } |
| |
| if (IsArg && !Inner) { |
| assert(N->getLocation().getAs<CallEnter>() && "Tracking arg but not at call"); |
| } else { |
| // Walk through nodes until we get one that matches the statement exactly. |
| // Alternately, if we hit a known lvalue for the statement, we know we've |
| // gone too far (though we can likely track the lvalue better anyway). |
| do { |
| const ProgramPoint &pp = N->getLocation(); |
| if (Optional<StmtPoint> ps = pp.getAs<StmtPoint>()) { |
| if (ps->getStmt() == S || ps->getStmt() == Inner) |
| break; |
| } else if (Optional<CallExitEnd> CEE = pp.getAs<CallExitEnd>()) { |
| if (CEE->getCalleeContext()->getCallSite() == S || |
| CEE->getCalleeContext()->getCallSite() == Inner) |
| break; |
| } |
| N = N->getFirstPred(); |
| } while (N); |
| |
| if (!N) |
| return false; |
| } |
| |
| ProgramStateRef state = N->getState(); |
| |
| // The message send could be nil due to the receiver being nil. |
| // At this point in the path, the receiver should be live since we are at the |
| // message send expr. If it is nil, start tracking it. |
| if (const Expr *Receiver = NilReceiverBRVisitor::getNilReceiver(S, N)) |
| trackNullOrUndefValue(N, Receiver, report, false, EnableNullFPSuppression); |
| |
| |
| // See if the expression we're interested refers to a variable. |
| // If so, we can track both its contents and constraints on its value. |
| if (Inner && ExplodedGraph::isInterestingLValueExpr(Inner)) { |
| const MemRegion *R = 0; |
| |
| // Find the ExplodedNode where the lvalue (the value of 'Ex') |
| // was computed. We need this for getting the location value. |
| const ExplodedNode *LVNode = N; |
| while (LVNode) { |
| if (Optional<PostStmt> P = LVNode->getLocation().getAs<PostStmt>()) { |
| if (P->getStmt() == Inner) |
| break; |
| } |
| LVNode = LVNode->getFirstPred(); |
| } |
| assert(LVNode && "Unable to find the lvalue node."); |
| ProgramStateRef LVState = LVNode->getState(); |
| SVal LVal = LVState->getSVal(Inner, LVNode->getLocationContext()); |
| |
| if (LVState->isNull(LVal).isConstrainedTrue()) { |
| // In case of C++ references, we want to differentiate between a null |
| // reference and reference to null pointer. |
| // If the LVal is null, check if we are dealing with null reference. |
| // For those, we want to track the location of the reference. |
| if (const MemRegion *RR = getLocationRegionIfReference(Inner, N)) |
| R = RR; |
| } else { |
| R = LVState->getSVal(Inner, LVNode->getLocationContext()).getAsRegion(); |
| |
| // If this is a C++ reference to a null pointer, we are tracking the |
| // pointer. In additon, we should find the store at which the reference |
| // got initialized. |
| if (const MemRegion *RR = getLocationRegionIfReference(Inner, N)) { |
| if (Optional<KnownSVal> KV = LVal.getAs<KnownSVal>()) |
| report.addVisitor(new FindLastStoreBRVisitor(*KV, RR, |
| EnableNullFPSuppression)); |
| } |
| } |
| |
| if (R) { |
| // Mark both the variable region and its contents as interesting. |
| SVal V = LVState->getRawSVal(loc::MemRegionVal(R)); |
| |
| report.markInteresting(R); |
| report.markInteresting(V); |
| report.addVisitor(new UndefOrNullArgVisitor(R)); |
| |
| // If the contents are symbolic, find out when they became null. |
| if (V.getAsLocSymbol(/*IncludeBaseRegions*/ true)) { |
| BugReporterVisitor *ConstraintTracker = |
| new TrackConstraintBRVisitor(V.castAs<DefinedSVal>(), false); |
| report.addVisitor(ConstraintTracker); |
| } |
| |
| // Add visitor, which will suppress inline defensive checks. |
| if (Optional<DefinedSVal> DV = V.getAs<DefinedSVal>()) { |
| if (!DV->isZeroConstant() && |
| LVState->isNull(*DV).isConstrainedTrue() && |
| EnableNullFPSuppression) { |
| BugReporterVisitor *IDCSuppressor = |
| new SuppressInlineDefensiveChecksVisitor(*DV, |
| LVNode); |
| report.addVisitor(IDCSuppressor); |
| } |
| } |
| |
| if (Optional<KnownSVal> KV = V.getAs<KnownSVal>()) |
| report.addVisitor(new FindLastStoreBRVisitor(*KV, R, |
| EnableNullFPSuppression)); |
| return true; |
| } |
| } |
| |
| // If the expression is not an "lvalue expression", we can still |
| // track the constraints on its contents. |
| SVal V = state->getSValAsScalarOrLoc(S, N->getLocationContext()); |
| |
| // If the value came from an inlined function call, we should at least make |
| // sure that function isn't pruned in our output. |
| if (const Expr *E = dyn_cast<Expr>(S)) |
| S = E->IgnoreParenCasts(); |
| |
| ReturnVisitor::addVisitorIfNecessary(N, S, report, EnableNullFPSuppression); |
| |
| // Uncomment this to find cases where we aren't properly getting the |
| // base value that was dereferenced. |
| // assert(!V.isUnknownOrUndef()); |
| // Is it a symbolic value? |
| if (Optional<loc::MemRegionVal> L = V.getAs<loc::MemRegionVal>()) { |
| // At this point we are dealing with the region's LValue. |
| // However, if the rvalue is a symbolic region, we should track it as well. |
| // Try to use the correct type when looking up the value. |
| SVal RVal; |
| if (const Expr *E = dyn_cast<Expr>(S)) |
| RVal = state->getRawSVal(L.getValue(), E->getType()); |
| else |
| RVal = state->getSVal(L->getRegion()); |
| |
| const MemRegion *RegionRVal = RVal.getAsRegion(); |
| report.addVisitor(new UndefOrNullArgVisitor(L->getRegion())); |
| |
| if (RegionRVal && isa<SymbolicRegion>(RegionRVal)) { |
| report.markInteresting(RegionRVal); |
| report.addVisitor(new TrackConstraintBRVisitor( |
| loc::MemRegionVal(RegionRVal), false)); |
| } |
| } |
| |
| return true; |
| } |
| |
| const Expr *NilReceiverBRVisitor::getNilReceiver(const Stmt *S, |
| const ExplodedNode *N) { |
| const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(S); |
| if (!ME) |
| return 0; |
| if (const Expr *Receiver = ME->getInstanceReceiver()) { |
| ProgramStateRef state = N->getState(); |
| SVal V = state->getSVal(Receiver, N->getLocationContext()); |
| if (state->isNull(V).isConstrainedTrue()) |
| return Receiver; |
| } |
| return 0; |
| } |
| |
| PathDiagnosticPiece *NilReceiverBRVisitor::VisitNode(const ExplodedNode *N, |
| const ExplodedNode *PrevN, |
| BugReporterContext &BRC, |
| BugReport &BR) { |
| Optional<PreStmt> P = N->getLocationAs<PreStmt>(); |
| if (!P) |
| return 0; |
| |
| const Stmt *S = P->getStmt(); |
| const Expr *Receiver = getNilReceiver(S, N); |
| if (!Receiver) |
| return 0; |
| |
| llvm::SmallString<256> Buf; |
| llvm::raw_svector_ostream OS(Buf); |
| |
| if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(S)) { |
| OS << "'"; |
| ME->getSelector().print(OS); |
| OS << "' not called"; |
| } |
| else { |
| OS << "No method is called"; |
| } |
| OS << " because the receiver is nil"; |
| |
| // The receiver was nil, and hence the method was skipped. |
| // Register a BugReporterVisitor to issue a message telling us how |
| // the receiver was null. |
| bugreporter::trackNullOrUndefValue(N, Receiver, BR, /*IsArg*/ false, |
| /*EnableNullFPSuppression*/ false); |
| // Issue a message saying that the method was skipped. |
| PathDiagnosticLocation L(Receiver, BRC.getSourceManager(), |
| N->getLocationContext()); |
| return new PathDiagnosticEventPiece(L, OS.str()); |
| } |
| |
| // Registers every VarDecl inside a Stmt with a last store visitor. |
| void FindLastStoreBRVisitor::registerStatementVarDecls(BugReport &BR, |
| const Stmt *S, |
| bool EnableNullFPSuppression) { |
| const ExplodedNode *N = BR.getErrorNode(); |
| std::deque<const Stmt *> WorkList; |
| WorkList.push_back(S); |
| |
| while (!WorkList.empty()) { |
| const Stmt *Head = WorkList.front(); |
| WorkList.pop_front(); |
| |
| ProgramStateRef state = N->getState(); |
| ProgramStateManager &StateMgr = state->getStateManager(); |
| |
| if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Head)) { |
| if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { |
| const VarRegion *R = |
| StateMgr.getRegionManager().getVarRegion(VD, N->getLocationContext()); |
| |
| // What did we load? |
| SVal V = state->getSVal(S, N->getLocationContext()); |
| |
| if (V.getAs<loc::ConcreteInt>() || V.getAs<nonloc::ConcreteInt>()) { |
| // Register a new visitor with the BugReport. |
| BR.addVisitor(new FindLastStoreBRVisitor(V.castAs<KnownSVal>(), R, |
| EnableNullFPSuppression)); |
| } |
| } |
| } |
| |
| for (Stmt::const_child_iterator I = Head->child_begin(); |
| I != Head->child_end(); ++I) |
| WorkList.push_back(*I); |
| } |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Visitor that tries to report interesting diagnostics from conditions. |
| //===----------------------------------------------------------------------===// |
| |
| /// Return the tag associated with this visitor. This tag will be used |
| /// to make all PathDiagnosticPieces created by this visitor. |
| const char *ConditionBRVisitor::getTag() { |
| return "ConditionBRVisitor"; |
| } |
| |
| PathDiagnosticPiece *ConditionBRVisitor::VisitNode(const ExplodedNode *N, |
| const ExplodedNode *Prev, |
| BugReporterContext &BRC, |
| BugReport &BR) { |
| PathDiagnosticPiece *piece = VisitNodeImpl(N, Prev, BRC, BR); |
| if (piece) { |
| piece->setTag(getTag()); |
| if (PathDiagnosticEventPiece *ev=dyn_cast<PathDiagnosticEventPiece>(piece)) |
| ev->setPrunable(true, /* override */ false); |
| } |
| return piece; |
| } |
| |
| PathDiagnosticPiece *ConditionBRVisitor::VisitNodeImpl(const ExplodedNode *N, |
| const ExplodedNode *Prev, |
| BugReporterContext &BRC, |
| BugReport &BR) { |
| |
| ProgramPoint progPoint = N->getLocation(); |
| ProgramStateRef CurrentState = N->getState(); |
| ProgramStateRef PrevState = Prev->getState(); |
| |
| // Compare the GDMs of the state, because that is where constraints |
| // are managed. Note that ensure that we only look at nodes that |
| // were generated by the analyzer engine proper, not checkers. |
| if (CurrentState->getGDM().getRoot() == |
| PrevState->getGDM().getRoot()) |
| return 0; |
| |
| // If an assumption was made on a branch, it should be caught |
| // here by looking at the state transition. |
| if (Optional<BlockEdge> BE = progPoint.getAs<BlockEdge>()) { |
| const CFGBlock *srcBlk = BE->getSrc(); |
| if (const Stmt *term = srcBlk->getTerminator()) |
| return VisitTerminator(term, N, srcBlk, BE->getDst(), BR, BRC); |
| return 0; |
| } |
| |
| if (Optional<PostStmt> PS = progPoint.getAs<PostStmt>()) { |
| // FIXME: Assuming that BugReporter is a GRBugReporter is a layering |
| // violation. |
| const std::pair<const ProgramPointTag *, const ProgramPointTag *> &tags = |
| cast<GRBugReporter>(BRC.getBugReporter()). |
| getEngine().geteagerlyAssumeBinOpBifurcationTags(); |
| |
| const ProgramPointTag *tag = PS->getTag(); |
| if (tag == tags.first) |
| return VisitTrueTest(cast<Expr>(PS->getStmt()), true, |
| BRC, BR, N); |
| if (tag == tags.second) |
| return VisitTrueTest(cast<Expr>(PS->getStmt()), false, |
| BRC, BR, N); |
| |
| return 0; |
| } |
| |
| return 0; |
| } |
| |
| PathDiagnosticPiece * |
| ConditionBRVisitor::VisitTerminator(const Stmt *Term, |
| const ExplodedNode *N, |
| const CFGBlock *srcBlk, |
| const CFGBlock *dstBlk, |
| BugReport &R, |
| BugReporterContext &BRC) { |
| const Expr *Cond = 0; |
| |
| switch (Term->getStmtClass()) { |
| default: |
| return 0; |
| case Stmt::IfStmtClass: |
| Cond = cast<IfStmt>(Term)->getCond(); |
| break; |
| case Stmt::ConditionalOperatorClass: |
| Cond = cast<ConditionalOperator>(Term)->getCond(); |
| break; |
| } |
| |
| assert(Cond); |
| assert(srcBlk->succ_size() == 2); |
| const bool tookTrue = *(srcBlk->succ_begin()) == dstBlk; |
| return VisitTrueTest(Cond, tookTrue, BRC, R, N); |
| } |
| |
| PathDiagnosticPiece * |
| ConditionBRVisitor::VisitTrueTest(const Expr *Cond, |
| bool tookTrue, |
| BugReporterContext &BRC, |
| BugReport &R, |
| const ExplodedNode *N) { |
| |
| const Expr *Ex = Cond; |
| |
| while (true) { |
| Ex = Ex->IgnoreParenCasts(); |
| switch (Ex->getStmtClass()) { |
| default: |
| return 0; |
| case Stmt::BinaryOperatorClass: |
| return VisitTrueTest(Cond, cast<BinaryOperator>(Ex), tookTrue, BRC, |
| R, N); |
| case Stmt::DeclRefExprClass: |
| return VisitTrueTest(Cond, cast<DeclRefExpr>(Ex), tookTrue, BRC, |
| R, N); |
| case Stmt::UnaryOperatorClass: { |
| const UnaryOperator *UO = cast<UnaryOperator>(Ex); |
| if (UO->getOpcode() == UO_LNot) { |
| tookTrue = !tookTrue; |
| Ex = UO->getSubExpr(); |
| continue; |
| } |
| return 0; |
| } |
| } |
| } |
| } |
| |
| bool ConditionBRVisitor::patternMatch(const Expr *Ex, raw_ostream &Out, |
| BugReporterContext &BRC, |
| BugReport &report, |
| const ExplodedNode *N, |
| Optional<bool> &prunable) { |
| const Expr *OriginalExpr = Ex; |
| Ex = Ex->IgnoreParenCasts(); |
| |
| if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Ex)) { |
| const bool quotes = isa<VarDecl>(DR->getDecl()); |
| if (quotes) { |
| Out << '\''; |
| const LocationContext *LCtx = N->getLocationContext(); |
| const ProgramState *state = N->getState().getPtr(); |
| if (const MemRegion *R = state->getLValue(cast<VarDecl>(DR->getDecl()), |
| LCtx).getAsRegion()) { |
| if (report.isInteresting(R)) |
| prunable = false; |
| else { |
| const ProgramState *state = N->getState().getPtr(); |
| SVal V = state->getSVal(R); |
| if (report.isInteresting(V)) |
| prunable = false; |
| } |
| } |
| } |
| Out << DR->getDecl()->getDeclName().getAsString(); |
| if (quotes) |
| Out << '\''; |
| return quotes; |
| } |
| |
| if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(Ex)) { |
| QualType OriginalTy = OriginalExpr->getType(); |
| if (OriginalTy->isPointerType()) { |
| if (IL->getValue() == 0) { |
| Out << "null"; |
| return false; |
| } |
| } |
| else if (OriginalTy->isObjCObjectPointerType()) { |
| if (IL->getValue() == 0) { |
| Out << "nil"; |
| return false; |
| } |
| } |
| |
| Out << IL->getValue(); |
| return false; |
| } |
| |
| return false; |
| } |
| |
| PathDiagnosticPiece * |
| ConditionBRVisitor::VisitTrueTest(const Expr *Cond, |
| const BinaryOperator *BExpr, |
| const bool tookTrue, |
| BugReporterContext &BRC, |
| BugReport &R, |
| const ExplodedNode *N) { |
| |
| bool shouldInvert = false; |
| Optional<bool> shouldPrune; |
| |
| SmallString<128> LhsString, RhsString; |
| { |
| llvm::raw_svector_ostream OutLHS(LhsString), OutRHS(RhsString); |
| const bool isVarLHS = patternMatch(BExpr->getLHS(), OutLHS, BRC, R, N, |
| shouldPrune); |
| const bool isVarRHS = patternMatch(BExpr->getRHS(), OutRHS, BRC, R, N, |
| shouldPrune); |
| |
| shouldInvert = !isVarLHS && isVarRHS; |
| } |
| |
| BinaryOperator::Opcode Op = BExpr->getOpcode(); |
| |
| if (BinaryOperator::isAssignmentOp(Op)) { |
| // For assignment operators, all that we care about is that the LHS |
| // evaluates to "true" or "false". |
| return VisitConditionVariable(LhsString, BExpr->getLHS(), tookTrue, |
| BRC, R, N); |
| } |
| |
| // For non-assignment operations, we require that we can understand |
| // both the LHS and RHS. |
| if (LhsString.empty() || RhsString.empty() || |
| !BinaryOperator::isComparisonOp(Op)) |
| return 0; |
| |
| // Should we invert the strings if the LHS is not a variable name? |
| SmallString<256> buf; |
| llvm::raw_svector_ostream Out(buf); |
| Out << "Assuming " << (shouldInvert ? RhsString : LhsString) << " is "; |
| |
| // Do we need to invert the opcode? |
| if (shouldInvert) |
| switch (Op) { |
| default: break; |
| case BO_LT: Op = BO_GT; break; |
| case BO_GT: Op = BO_LT; break; |
| case BO_LE: Op = BO_GE; break; |
| case BO_GE: Op = BO_LE; break; |
| } |
| |
| if (!tookTrue) |
| switch (Op) { |
| case BO_EQ: Op = BO_NE; break; |
| case BO_NE: Op = BO_EQ; break; |
| case BO_LT: Op = BO_GE; break; |
| case BO_GT: Op = BO_LE; break; |
| case BO_LE: Op = BO_GT; break; |
| case BO_GE: Op = BO_LT; break; |
| default: |
| return 0; |
| } |
| |
| switch (Op) { |
| case BO_EQ: |
| Out << "equal to "; |
| break; |
| case BO_NE: |
| Out << "not equal to "; |
| break; |
| default: |
| Out << BinaryOperator::getOpcodeStr(Op) << ' '; |
| break; |
| } |
| |
| Out << (shouldInvert ? LhsString : RhsString); |
| const LocationContext *LCtx = N->getLocationContext(); |
| PathDiagnosticLocation Loc(Cond, BRC.getSourceManager(), LCtx); |
| PathDiagnosticEventPiece *event = |
| new PathDiagnosticEventPiece(Loc, Out.str()); |
| if (shouldPrune.hasValue()) |
| event->setPrunable(shouldPrune.getValue()); |
| return event; |
| } |
| |
| PathDiagnosticPiece * |
| ConditionBRVisitor::VisitConditionVariable(StringRef LhsString, |
| const Expr *CondVarExpr, |
| const bool tookTrue, |
| BugReporterContext &BRC, |
| BugReport &report, |
| const ExplodedNode *N) { |
| // FIXME: If there's already a constraint tracker for this variable, |
| // we shouldn't emit anything here (c.f. the double note in |
| // test/Analysis/inlining/path-notes.c) |
| SmallString<256> buf; |
| llvm::raw_svector_ostream Out(buf); |
| Out << "Assuming " << LhsString << " is "; |
| |
| QualType Ty = CondVarExpr->getType(); |
| |
| if (Ty->isPointerType()) |
| Out << (tookTrue ? "not null" : "null"); |
| else if (Ty->isObjCObjectPointerType()) |
| Out << (tookTrue ? "not nil" : "nil"); |
| else if (Ty->isBooleanType()) |
| Out << (tookTrue ? "true" : "false"); |
| else if (Ty->isIntegralOrEnumerationType()) |
| Out << (tookTrue ? "non-zero" : "zero"); |
| else |
| return 0; |
| |
| const LocationContext *LCtx = N->getLocationContext(); |
| PathDiagnosticLocation Loc(CondVarExpr, BRC.getSourceManager(), LCtx); |
| PathDiagnosticEventPiece *event = |
| new PathDiagnosticEventPiece(Loc, Out.str()); |
| |
| if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(CondVarExpr)) { |
| if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { |
| const ProgramState *state = N->getState().getPtr(); |
| if (const MemRegion *R = state->getLValue(VD, LCtx).getAsRegion()) { |
| if (report.isInteresting(R)) |
| event->setPrunable(false); |
| } |
| } |
| } |
| |
| return event; |
| } |
| |
| PathDiagnosticPiece * |
| ConditionBRVisitor::VisitTrueTest(const Expr *Cond, |
| const DeclRefExpr *DR, |
| const bool tookTrue, |
| BugReporterContext &BRC, |
| BugReport &report, |
| const ExplodedNode *N) { |
| |
| const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl()); |
| if (!VD) |
| return 0; |
| |
| SmallString<256> Buf; |
| llvm::raw_svector_ostream Out(Buf); |
| |
| Out << "Assuming '" << VD->getDeclName() << "' is "; |
| |
| QualType VDTy = VD->getType(); |
| |
| if (VDTy->isPointerType()) |
| Out << (tookTrue ? "non-null" : "null"); |
| else if (VDTy->isObjCObjectPointerType()) |
| Out << (tookTrue ? "non-nil" : "nil"); |
| else if (VDTy->isScalarType()) |
| Out << (tookTrue ? "not equal to 0" : "0"); |
| else |
| return 0; |
| |
| const LocationContext *LCtx = N->getLocationContext(); |
| PathDiagnosticLocation Loc(Cond, BRC.getSourceManager(), LCtx); |
| PathDiagnosticEventPiece *event = |
| new PathDiagnosticEventPiece(Loc, Out.str()); |
| |
| const ProgramState *state = N->getState().getPtr(); |
| if (const MemRegion *R = state->getLValue(VD, LCtx).getAsRegion()) { |
| if (report.isInteresting(R)) |
| event->setPrunable(false); |
| else { |
| SVal V = state->getSVal(R); |
| if (report.isInteresting(V)) |
| event->setPrunable(false); |
| } |
| } |
| return event; |
| } |
| |
| |
| // FIXME: Copied from ExprEngineCallAndReturn.cpp. |
| static bool isInStdNamespace(const Decl *D) { |
| const DeclContext *DC = D->getDeclContext()->getEnclosingNamespaceContext(); |
| const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(DC); |
| if (!ND) |
| return false; |
| |
| while (const NamespaceDecl *Parent = dyn_cast<NamespaceDecl>(ND->getParent())) |
| ND = Parent; |
| |
| return ND->getName() == "std"; |
| } |
| |
| |
| PathDiagnosticPiece * |
| LikelyFalsePositiveSuppressionBRVisitor::getEndPath(BugReporterContext &BRC, |
| const ExplodedNode *N, |
| BugReport &BR) { |
| // Here we suppress false positives coming from system headers. This list is |
| // based on known issues. |
| ExprEngine &Eng = BRC.getBugReporter().getEngine(); |
| AnalyzerOptions &Options = Eng.getAnalysisManager().options; |
| const Decl *D = N->getLocationContext()->getDecl(); |
| |
| if (isInStdNamespace(D)) { |
| // Skip reports within the 'std' namespace. Although these can sometimes be |
| // the user's fault, we currently don't report them very well, and |
| // Note that this will not help for any other data structure libraries, like |
| // TR1, Boost, or llvm/ADT. |
| if (Options.shouldSuppressFromCXXStandardLibrary()) { |
| BR.markInvalid(getTag(), 0); |
| return 0; |
| |
| } else { |
| // If the the complete 'std' suppression is not enabled, suppress reports |
| // from the 'std' namespace that are known to produce false positives. |
| |
| // The analyzer issues a false use-after-free when std::list::pop_front |
| // or std::list::pop_back are called multiple times because we cannot |
| // reason about the internal invariants of the datastructure. |
| if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(D)) { |
| const CXXRecordDecl *CD = MD->getParent(); |
| if (CD->getName() == "list") { |
| BR.markInvalid(getTag(), 0); |
| return 0; |
| } |
| } |
| |
| // The analyzer issues a false positive on |
| // std::basic_string<uint8_t> v; v.push_back(1); |
| // and |
| // std::u16string s; s += u'a'; |
| // because we cannot reason about the internal invariants of the |
| // datastructure. |
| for (const LocationContext *LCtx = N->getLocationContext(); LCtx; |
| LCtx = LCtx->getParent()) { |
| const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(LCtx->getDecl()); |
| if (!MD) |
| continue; |
| |
| const CXXRecordDecl *CD = MD->getParent(); |
| if (CD->getName() == "basic_string") { |
| BR.markInvalid(getTag(), 0); |
| return 0; |
| } |
| } |
| } |
| } |
| |
| // Skip reports within the sys/queue.h macros as we do not have the ability to |
| // reason about data structure shapes. |
| SourceManager &SM = BRC.getSourceManager(); |
| FullSourceLoc Loc = BR.getLocation(SM).asLocation(); |
| while (Loc.isMacroID()) { |
| Loc = Loc.getSpellingLoc(); |
| if (SM.getFilename(Loc).endswith("sys/queue.h")) { |
| BR.markInvalid(getTag(), 0); |
| return 0; |
| } |
| } |
| |
| return 0; |
| } |
| |
| PathDiagnosticPiece * |
| UndefOrNullArgVisitor::VisitNode(const ExplodedNode *N, |
| const ExplodedNode *PrevN, |
| BugReporterContext &BRC, |
| BugReport &BR) { |
| |
| ProgramStateRef State = N->getState(); |
| ProgramPoint ProgLoc = N->getLocation(); |
| |
| // We are only interested in visiting CallEnter nodes. |
| Optional<CallEnter> CEnter = ProgLoc.getAs<CallEnter>(); |
| if (!CEnter) |
| return 0; |
| |
| // Check if one of the arguments is the region the visitor is tracking. |
| CallEventManager &CEMgr = BRC.getStateManager().getCallEventManager(); |
| CallEventRef<> Call = CEMgr.getCaller(CEnter->getCalleeContext(), State); |
| unsigned Idx = 0; |
| ArrayRef<ParmVarDecl*> parms = Call->parameters(); |
| |
| for (ArrayRef<ParmVarDecl*>::iterator I = parms.begin(), E = parms.end(); |
| I != E; ++I, ++Idx) { |
| const MemRegion *ArgReg = Call->getArgSVal(Idx).getAsRegion(); |
| |
| // Are we tracking the argument or its subregion? |
| if ( !ArgReg || (ArgReg != R && !R->isSubRegionOf(ArgReg->StripCasts()))) |
| continue; |
| |
| // Check the function parameter type. |
| const ParmVarDecl *ParamDecl = *I; |
| assert(ParamDecl && "Formal parameter has no decl?"); |
| QualType T = ParamDecl->getType(); |
| |
| if (!(T->isAnyPointerType() || T->isReferenceType())) { |
| // Function can only change the value passed in by address. |
| continue; |
| } |
| |
| // If it is a const pointer value, the function does not intend to |
| // change the value. |
| if (T->getPointeeType().isConstQualified()) |
| continue; |
| |
| // Mark the call site (LocationContext) as interesting if the value of the |
| // argument is undefined or '0'/'NULL'. |
| SVal BoundVal = State->getSVal(R); |
| if (BoundVal.isUndef() || BoundVal.isZeroConstant()) { |
| BR.markInteresting(CEnter->getCalleeContext()); |
| return 0; |
| } |
| } |
| return 0; |
| } |