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- // 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 nullptr;
- 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 nullptr;
- }
- 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 nullptr;
- }
- 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 nullptr;
- }
- //===----------------------------------------------------------------------===//
- // Definitions for bug reporter visitors.
- //===----------------------------------------------------------------------===//
- PathDiagnosticPiece*
- BugReporterVisitor::getEndPath(BugReporterContext &BRC,
- const ExplodedNode *EndPathNode,
- BugReport &BR) {
- return nullptr;
- }
- 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 nullptr;
- Optional<StmtPoint> SP = N->getLocationAs<StmtPoint>();
- if (!SP)
- return nullptr;
- const ReturnStmt *Ret = dyn_cast<ReturnStmt>(SP->getStmt());
- if (!Ret)
- return nullptr;
- // 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 nullptr;
- // 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 nullptr;
- 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 nullptr;
- }
-
- // 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 nullptr;
- if (CE->getCalleeContext() != StackFrame)
- return nullptr;
- 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 nullptr;
- }
- 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 nullptr;
- }
- llvm_unreachable("Invalid visit mode!");
- }
- PathDiagnosticPiece *getEndPath(BugReporterContext &BRC,
- const ExplodedNode *N,
- BugReport &BR) override {
- if (EnableNullFPSuppression)
- BR.markInvalid(ReturnVisitor::getTag(), StackFrame);
- return nullptr;
- }
- };
- } // 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 nullptr;
- const ExplodedNode *StoreSite = nullptr;
- const Expr *InitE = nullptr;
- 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 nullptr;
- if (Pred->getState()->getSVal(R) == V) {
- Optional<PostStore> PS = Succ->getLocationAs<PostStore>();
- if (!PS || PS->getLocationValue() != R)
- return nullptr;
- }
- 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 nullptr;
- 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 = nullptr;
- 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 nullptr;
- 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 nullptr;
- // Start tracking after we see the first state in which the value is
- // constrained.
- if (!IsTrackingTurnedOn)
- if (!isUnderconstrained(N))
- IsTrackingTurnedOn = true;
- if (!IsTrackingTurnedOn)
- return nullptr;
- // 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 nullptr;
- // Construct a new PathDiagnosticPiece.
- ProgramPoint P = N->getLocation();
- PathDiagnosticLocation L =
- PathDiagnosticLocation::create(P, BRC.getSourceManager());
- if (!L.isValid())
- return nullptr;
- PathDiagnosticEventPiece *X = new PathDiagnosticEventPiece(L, os.str());
- X->setTag(getTag());
- return X;
- }
- return nullptr;
- }
- 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 nullptr;
- // 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 nullptr;
- // 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 nullptr;
- }
- 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 nullptr;
- 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 nullptr;
- }
- 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 = nullptr;
- 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 = nullptr;
- // 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 nullptr;
- 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 nullptr;
- }
- PathDiagnosticPiece *NilReceiverBRVisitor::VisitNode(const ExplodedNode *N,
- const ExplodedNode *PrevN,
- BugReporterContext &BRC,
- BugReport &BR) {
- Optional<PreStmt> P = N->getLocationAs<PreStmt>();
- if (!P)
- return nullptr;
- const Stmt *S = P->getStmt();
- const Expr *Receiver = getNilReceiver(S, N);
- if (!Receiver)
- return nullptr;
- 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 nullptr;
- // 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 nullptr;
- }
-
- 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 nullptr;
- }
- return nullptr;
- }
- PathDiagnosticPiece *
- ConditionBRVisitor::VisitTerminator(const Stmt *Term,
- const ExplodedNode *N,
- const CFGBlock *srcBlk,
- const CFGBlock *dstBlk,
- BugReport &R,
- BugReporterContext &BRC) {
- const Expr *Cond = nullptr;
- switch (Term->getStmtClass()) {
- default:
- return nullptr;
- 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 nullptr;
- 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 nullptr;
- }
- }
- }
- }
- 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 nullptr;
- // 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 nullptr;
- }
-
- 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 nullptr;
- 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 nullptr;
- 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 nullptr;
- 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(), nullptr);
- return nullptr;
- } 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(), nullptr);
- return nullptr;
- }
- }
- // 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(), nullptr);
- return nullptr;
- }
- }
- }
- }
- // 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(), nullptr);
- return nullptr;
- }
- }
- return nullptr;
- }
- 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 nullptr;
- // 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 nullptr;
- }
- }
- return nullptr;
- }
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