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llvm-project/clang/lib/StaticAnalyzer/Checkers/RetainCountChecker/RetainCountDiagnostics.cpp

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// RetainCountDiagnostics.cpp - Checks for leaks and other issues -*- C++ -*--//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines diagnostics for RetainCountChecker, which implements
// a reference count checker for Core Foundation and Cocoa on (Mac OS X).
//
//===----------------------------------------------------------------------===//
#include "RetainCountDiagnostics.h"
#include "RetainCountChecker.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
using namespace clang;
using namespace ento;
using namespace retaincountchecker;
StringRef RefCountBug::bugTypeToName(RefCountBug::RefCountBugKind BT) {
switch (BT) {
case UseAfterRelease:
return "Use-after-release";
case ReleaseNotOwned:
return "Bad release";
case DeallocNotOwned:
return "-dealloc sent to non-exclusively owned object";
case FreeNotOwned:
return "freeing non-exclusively owned object";
case OverAutorelease:
return "Object autoreleased too many times";
case ReturnNotOwnedForOwned:
return "Method should return an owned object";
case LeakWithinFunction:
return "Leak";
case LeakAtReturn:
return "Leak of returned object";
}
llvm_unreachable("Unknown RefCountBugKind");
}
StringRef RefCountBug::getDescription() const {
switch (BT) {
case UseAfterRelease:
return "Reference-counted object is used after it is released";
case ReleaseNotOwned:
return "Incorrect decrement of the reference count of an object that is "
"not owned at this point by the caller";
case DeallocNotOwned:
return "-dealloc sent to object that may be referenced elsewhere";
case FreeNotOwned:
return "'free' called on an object that may be referenced elsewhere";
case OverAutorelease:
return "Object autoreleased too many times";
case ReturnNotOwnedForOwned:
return "Object with a +0 retain count returned to caller where a +1 "
"(owning) retain count is expected";
case LeakWithinFunction:
case LeakAtReturn:
return "";
}
llvm_unreachable("Unknown RefCountBugKind");
}
RefCountBug::RefCountBug(CheckerNameRef Checker, RefCountBugKind BT)
: BugType(Checker, bugTypeToName(BT), categories::MemoryRefCount,
/*SuppressOnSink=*/BT == LeakWithinFunction ||
BT == LeakAtReturn),
BT(BT) {}
static bool isNumericLiteralExpression(const Expr *E) {
// FIXME: This set of cases was copied from SemaExprObjC.
return isa<IntegerLiteral, CharacterLiteral, FloatingLiteral,
ObjCBoolLiteralExpr, CXXBoolLiteralExpr>(E);
}
/// If type represents a pointer to CXXRecordDecl,
/// and is not a typedef, return the decl name.
/// Otherwise, return the serialization of type.
static std::string getPrettyTypeName(QualType QT) {
QualType PT = QT->getPointeeType();
if (!PT.isNull() && !QT->getAs<TypedefType>())
if (const auto *RD = PT->getAsCXXRecordDecl())
return std::string(RD->getName());
return QT.getAsString();
}
/// Write information about the type state change to @c os,
/// return whether the note should be generated.
static bool shouldGenerateNote(llvm::raw_string_ostream &os,
const RefVal *PrevT,
const RefVal &CurrV,
bool DeallocSent) {
// Get the previous type state.
RefVal PrevV = *PrevT;
// Specially handle -dealloc.
if (DeallocSent) {
// Determine if the object's reference count was pushed to zero.
assert(!PrevV.hasSameState(CurrV) && "The state should have changed.");
// We may not have transitioned to 'release' if we hit an error.
// This case is handled elsewhere.
if (CurrV.getKind() == RefVal::Released) {
assert(CurrV.getCombinedCounts() == 0);
os << "Object released by directly sending the '-dealloc' message";
return true;
}
}
// Determine if the typestate has changed.
if (!PrevV.hasSameState(CurrV))
switch (CurrV.getKind()) {
case RefVal::Owned:
case RefVal::NotOwned:
if (PrevV.getCount() == CurrV.getCount()) {
// Did an autorelease message get sent?
if (PrevV.getAutoreleaseCount() == CurrV.getAutoreleaseCount())
return false;
assert(PrevV.getAutoreleaseCount() < CurrV.getAutoreleaseCount());
os << "Object autoreleased";
return true;
}
if (PrevV.getCount() > CurrV.getCount())
os << "Reference count decremented.";
else
os << "Reference count incremented.";
if (unsigned Count = CurrV.getCount())
os << " The object now has a +" << Count << " retain count.";
return true;
case RefVal::Released:
if (CurrV.getIvarAccessHistory() ==
RefVal::IvarAccessHistory::ReleasedAfterDirectAccess &&
CurrV.getIvarAccessHistory() != PrevV.getIvarAccessHistory()) {
os << "Strong instance variable relinquished. ";
}
os << "Object released.";
return true;
case RefVal::ReturnedOwned:
// Autoreleases can be applied after marking a node ReturnedOwned.
if (CurrV.getAutoreleaseCount())
return false;
os << "Object returned to caller as an owning reference (single "
"retain count transferred to caller)";
return true;
case RefVal::ReturnedNotOwned:
os << "Object returned to caller with a +0 retain count";
return true;
default:
return false;
}
return true;
}
/// Finds argument index of the out paramter in the call @c S
/// corresponding to the symbol @c Sym.
/// If none found, returns None.
static Optional<unsigned> findArgIdxOfSymbol(ProgramStateRef CurrSt,
const LocationContext *LCtx,
SymbolRef &Sym,
Optional<CallEventRef<>> CE) {
if (!CE)
return None;
for (unsigned Idx = 0; Idx < (*CE)->getNumArgs(); Idx++)
if (const MemRegion *MR = (*CE)->getArgSVal(Idx).getAsRegion())
if (const auto *TR = dyn_cast<TypedValueRegion>(MR))
if (CurrSt->getSVal(MR, TR->getValueType()).getAsSymbol() == Sym)
return Idx;
return None;
}
static Optional<std::string> findMetaClassAlloc(const Expr *Callee) {
if (const auto *ME = dyn_cast<MemberExpr>(Callee)) {
if (ME->getMemberDecl()->getNameAsString() != "alloc")
return None;
const Expr *This = ME->getBase()->IgnoreParenImpCasts();
if (const auto *DRE = dyn_cast<DeclRefExpr>(This)) {
const ValueDecl *VD = DRE->getDecl();
if (VD->getNameAsString() != "metaClass")
return None;
if (const auto *RD = dyn_cast<CXXRecordDecl>(VD->getDeclContext()))
return RD->getNameAsString();
}
}
return None;
}
static std::string findAllocatedObjectName(const Stmt *S, QualType QT) {
if (const auto *CE = dyn_cast<CallExpr>(S))
if (auto Out = findMetaClassAlloc(CE->getCallee()))
return *Out;
return getPrettyTypeName(QT);
}
static void generateDiagnosticsForCallLike(ProgramStateRef CurrSt,
const LocationContext *LCtx,
const RefVal &CurrV, SymbolRef &Sym,
const Stmt *S,
llvm::raw_string_ostream &os) {
CallEventManager &Mgr = CurrSt->getStateManager().getCallEventManager();
if (const CallExpr *CE = dyn_cast<CallExpr>(S)) {
// Get the name of the callee (if it is available)
// from the tracked SVal.
SVal X = CurrSt->getSValAsScalarOrLoc(CE->getCallee(), LCtx);
const FunctionDecl *FD = X.getAsFunctionDecl();
// If failed, try to get it from AST.
if (!FD)
FD = dyn_cast<FunctionDecl>(CE->getCalleeDecl());
if (const auto *MD = dyn_cast<CXXMethodDecl>(CE->getCalleeDecl())) {
os << "Call to method '" << MD->getQualifiedNameAsString() << '\'';
} else if (FD) {
os << "Call to function '" << FD->getQualifiedNameAsString() << '\'';
} else {
os << "function call";
}
} else if (isa<CXXNewExpr>(S)) {
os << "Operator 'new'";
} else {
assert(isa<ObjCMessageExpr>(S));
CallEventRef<ObjCMethodCall> Call =
Mgr.getObjCMethodCall(cast<ObjCMessageExpr>(S), CurrSt, LCtx);
switch (Call->getMessageKind()) {
case OCM_Message:
os << "Method";
break;
case OCM_PropertyAccess:
os << "Property";
break;
case OCM_Subscript:
os << "Subscript";
break;
}
}
Optional<CallEventRef<>> CE = Mgr.getCall(S, CurrSt, LCtx);
auto Idx = findArgIdxOfSymbol(CurrSt, LCtx, Sym, CE);
// If index is not found, we assume that the symbol was returned.
if (!Idx) {
os << " returns ";
} else {
os << " writes ";
}
if (CurrV.getObjKind() == ObjKind::CF) {
os << "a Core Foundation object of type '" << Sym->getType() << "' with a ";
} else if (CurrV.getObjKind() == ObjKind::OS) {
os << "an OSObject of type '" << findAllocatedObjectName(S, Sym->getType())
<< "' with a ";
} else if (CurrV.getObjKind() == ObjKind::Generalized) {
os << "an object of type '" << Sym->getType() << "' with a ";
} else {
assert(CurrV.getObjKind() == ObjKind::ObjC);
QualType T = Sym->getType();
if (!isa<ObjCObjectPointerType>(T)) {
os << "an Objective-C object with a ";
} else {
const ObjCObjectPointerType *PT = cast<ObjCObjectPointerType>(T);
os << "an instance of " << PT->getPointeeType() << " with a ";
}
}
if (CurrV.isOwned()) {
os << "+1 retain count";
} else {
assert(CurrV.isNotOwned());
os << "+0 retain count";
}
if (Idx) {
os << " into an out parameter '";
const ParmVarDecl *PVD = (*CE)->parameters()[*Idx];
PVD->getNameForDiagnostic(os, PVD->getASTContext().getPrintingPolicy(),
/*Qualified=*/false);
os << "'";
QualType RT = (*CE)->getResultType();
if (!RT.isNull() && !RT->isVoidType()) {
SVal RV = (*CE)->getReturnValue();
if (CurrSt->isNull(RV).isConstrainedTrue()) {
os << " (assuming the call returns zero)";
} else if (CurrSt->isNonNull(RV).isConstrainedTrue()) {
os << " (assuming the call returns non-zero)";
}
}
}
}
namespace clang {
namespace ento {
namespace retaincountchecker {
class RefCountReportVisitor : public BugReporterVisitor {
protected:
SymbolRef Sym;
public:
RefCountReportVisitor(SymbolRef sym) : Sym(sym) {}
void Profile(llvm::FoldingSetNodeID &ID) const override {
static int x = 0;
ID.AddPointer(&x);
ID.AddPointer(Sym);
}
PathDiagnosticPieceRef VisitNode(const ExplodedNode *N,
BugReporterContext &BRC,
PathSensitiveBugReport &BR) override;
PathDiagnosticPieceRef getEndPath(BugReporterContext &BRC,
const ExplodedNode *N,
PathSensitiveBugReport &BR) override;
};
class RefLeakReportVisitor : public RefCountReportVisitor {
public:
RefLeakReportVisitor(SymbolRef Sym, const MemRegion *LastBinding)
: RefCountReportVisitor(Sym), LastBinding(LastBinding) {}
PathDiagnosticPieceRef getEndPath(BugReporterContext &BRC,
const ExplodedNode *N,
PathSensitiveBugReport &BR) override;
private:
const MemRegion *LastBinding;
};
} // end namespace retaincountchecker
} // end namespace ento
} // end namespace clang
/// Find the first node with the parent stack frame.
static const ExplodedNode *getCalleeNode(const ExplodedNode *Pred) {
const StackFrameContext *SC = Pred->getStackFrame();
if (SC->inTopFrame())
return nullptr;
const StackFrameContext *PC = SC->getParent()->getStackFrame();
if (!PC)
return nullptr;
const ExplodedNode *N = Pred;
while (N && N->getStackFrame() != PC) {
N = N->getFirstPred();
}
return N;
}
/// Insert a diagnostic piece at function exit
/// if a function parameter is annotated as "os_consumed",
/// but it does not actually consume the reference.
static std::shared_ptr<PathDiagnosticEventPiece>
annotateConsumedSummaryMismatch(const ExplodedNode *N,
CallExitBegin &CallExitLoc,
const SourceManager &SM,
CallEventManager &CEMgr) {
const ExplodedNode *CN = getCalleeNode(N);
if (!CN)
return nullptr;
CallEventRef<> Call = CEMgr.getCaller(N->getStackFrame(), N->getState());
std::string sbuf;
llvm::raw_string_ostream os(sbuf);
ArrayRef<const ParmVarDecl *> Parameters = Call->parameters();
for (unsigned I=0; I < Call->getNumArgs() && I < Parameters.size(); ++I) {
const ParmVarDecl *PVD = Parameters[I];
if (!PVD->hasAttr<OSConsumedAttr>())
continue;
if (SymbolRef SR = Call->getArgSVal(I).getAsLocSymbol()) {
const RefVal *CountBeforeCall = getRefBinding(CN->getState(), SR);
const RefVal *CountAtExit = getRefBinding(N->getState(), SR);
if (!CountBeforeCall || !CountAtExit)
continue;
unsigned CountBefore = CountBeforeCall->getCount();
unsigned CountAfter = CountAtExit->getCount();
bool AsExpected = CountBefore > 0 && CountAfter == CountBefore - 1;
if (!AsExpected) {
os << "Parameter '";
PVD->getNameForDiagnostic(os, PVD->getASTContext().getPrintingPolicy(),
/*Qualified=*/false);
os << "' is marked as consuming, but the function did not consume "
<< "the reference\n";
}
}
}
if (os.str().empty())
return nullptr;
PathDiagnosticLocation L = PathDiagnosticLocation::create(CallExitLoc, SM);
return std::make_shared<PathDiagnosticEventPiece>(L, os.str());
}
/// Annotate the parameter at the analysis entry point.
static std::shared_ptr<PathDiagnosticEventPiece>
annotateStartParameter(const ExplodedNode *N, SymbolRef Sym,
const SourceManager &SM) {
auto PP = N->getLocationAs<BlockEdge>();
if (!PP)
return nullptr;
const CFGBlock *Src = PP->getSrc();
const RefVal *CurrT = getRefBinding(N->getState(), Sym);
if (&Src->getParent()->getEntry() != Src || !CurrT ||
getRefBinding(N->getFirstPred()->getState(), Sym))
return nullptr;
const auto *VR = cast<VarRegion>(cast<SymbolRegionValue>(Sym)->getRegion());
const auto *PVD = cast<ParmVarDecl>(VR->getDecl());
PathDiagnosticLocation L = PathDiagnosticLocation(PVD, SM);
std::string s;
llvm::raw_string_ostream os(s);
os << "Parameter '" << PVD->getDeclName() << "' starts at +";
if (CurrT->getCount() == 1) {
os << "1, as it is marked as consuming";
} else {
assert(CurrT->getCount() == 0);
os << "0";
}
return std::make_shared<PathDiagnosticEventPiece>(L, os.str());
}
PathDiagnosticPieceRef
RefCountReportVisitor::VisitNode(const ExplodedNode *N, BugReporterContext &BRC,
PathSensitiveBugReport &BR) {
const auto &BT = static_cast<const RefCountBug&>(BR.getBugType());
bool IsFreeUnowned = BT.getBugType() == RefCountBug::FreeNotOwned ||
BT.getBugType() == RefCountBug::DeallocNotOwned;
const SourceManager &SM = BRC.getSourceManager();
CallEventManager &CEMgr = BRC.getStateManager().getCallEventManager();
if (auto CE = N->getLocationAs<CallExitBegin>())
if (auto PD = annotateConsumedSummaryMismatch(N, *CE, SM, CEMgr))
return PD;
if (auto PD = annotateStartParameter(N, Sym, SM))
return PD;
// FIXME: We will eventually need to handle non-statement-based events
// (__attribute__((cleanup))).
if (!N->getLocation().getAs<StmtPoint>())
return nullptr;
// Check if the type state has changed.
const ExplodedNode *PrevNode = N->getFirstPred();
ProgramStateRef PrevSt = PrevNode->getState();
ProgramStateRef CurrSt = N->getState();
const LocationContext *LCtx = N->getLocationContext();
const RefVal* CurrT = getRefBinding(CurrSt, Sym);
if (!CurrT)
return nullptr;
const RefVal &CurrV = *CurrT;
const RefVal *PrevT = getRefBinding(PrevSt, Sym);
// Create a string buffer to constain all the useful things we want
// to tell the user.
std::string sbuf;
llvm::raw_string_ostream os(sbuf);
if (PrevT && IsFreeUnowned && CurrV.isNotOwned() && PrevT->isOwned()) {
os << "Object is now not exclusively owned";
auto Pos = PathDiagnosticLocation::create(N->getLocation(), SM);
return std::make_shared<PathDiagnosticEventPiece>(Pos, os.str());
}
// This is the allocation site since the previous node had no bindings
// for this symbol.
if (!PrevT) {
const Stmt *S = N->getLocation().castAs<StmtPoint>().getStmt();
if (isa<ObjCIvarRefExpr>(S) &&
isSynthesizedAccessor(LCtx->getStackFrame())) {
S = LCtx->getStackFrame()->getCallSite();
}
if (isa<ObjCArrayLiteral>(S)) {
os << "NSArray literal is an object with a +0 retain count";
} else if (isa<ObjCDictionaryLiteral>(S)) {
os << "NSDictionary literal is an object with a +0 retain count";
} else if (const ObjCBoxedExpr *BL = dyn_cast<ObjCBoxedExpr>(S)) {
if (isNumericLiteralExpression(BL->getSubExpr()))
os << "NSNumber literal is an object with a +0 retain count";
else {
const ObjCInterfaceDecl *BoxClass = nullptr;
if (const ObjCMethodDecl *Method = BL->getBoxingMethod())
BoxClass = Method->getClassInterface();
// We should always be able to find the boxing class interface,
// but consider this future-proofing.
if (BoxClass) {
os << *BoxClass << " b";
} else {
os << "B";
}
os << "oxed expression produces an object with a +0 retain count";
}
} else if (isa<ObjCIvarRefExpr>(S)) {
os << "Object loaded from instance variable";
} else {
generateDiagnosticsForCallLike(CurrSt, LCtx, CurrV, Sym, S, os);
}
PathDiagnosticLocation Pos(S, SM, N->getLocationContext());
return std::make_shared<PathDiagnosticEventPiece>(Pos, os.str());
}
// Gather up the effects that were performed on the object at this
// program point
bool DeallocSent = false;
const ProgramPointTag *Tag = N->getLocation().getTag();
if (Tag == &RetainCountChecker::getCastFailTag()) {
os << "Assuming dynamic cast returns null due to type mismatch";
}
if (Tag == &RetainCountChecker::getDeallocSentTag()) {
// We only have summaries attached to nodes after evaluating CallExpr and
// ObjCMessageExprs.
const Stmt *S = N->getLocation().castAs<StmtPoint>().getStmt();
if (const CallExpr *CE = dyn_cast<CallExpr>(S)) {
// Iterate through the parameter expressions and see if the symbol
// was ever passed as an argument.
unsigned i = 0;
for (auto AI=CE->arg_begin(), AE=CE->arg_end(); AI!=AE; ++AI, ++i) {
// Retrieve the value of the argument. Is it the symbol
// we are interested in?
if (CurrSt->getSValAsScalarOrLoc(*AI, LCtx).getAsLocSymbol() != Sym)
continue;
// We have an argument. Get the effect!
DeallocSent = true;
}
} else if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(S)) {
if (const Expr *receiver = ME->getInstanceReceiver()) {
if (CurrSt->getSValAsScalarOrLoc(receiver, LCtx)
.getAsLocSymbol() == Sym) {
// The symbol we are tracking is the receiver.
DeallocSent = true;
}
}
}
}
if (!shouldGenerateNote(os, PrevT, CurrV, DeallocSent))
return nullptr;
if (os.str().empty())
return nullptr; // We have nothing to say!
const Stmt *S = N->getLocation().castAs<StmtPoint>().getStmt();
PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
N->getLocationContext());
auto P = std::make_shared<PathDiagnosticEventPiece>(Pos, os.str());
// Add the range by scanning the children of the statement for any bindings
// to Sym.
for (const Stmt *Child : S->children())
if (const Expr *Exp = dyn_cast_or_null<Expr>(Child))
if (CurrSt->getSValAsScalarOrLoc(Exp, LCtx).getAsLocSymbol() == Sym) {
P->addRange(Exp->getSourceRange());
break;
}
return std::move(P);
}
static Optional<std::string> describeRegion(const MemRegion *MR) {
if (const auto *VR = dyn_cast_or_null<VarRegion>(MR))
return std::string(VR->getDecl()->getName());
// Once we support more storage locations for bindings,
// this would need to be improved.
return None;
}
using Bindings = llvm::SmallVector<std::pair<const MemRegion *, SVal>, 4>;
class VarBindingsCollector : public StoreManager::BindingsHandler {
SymbolRef Sym;
Bindings &Result;
public:
VarBindingsCollector(SymbolRef Sym, Bindings &ToFill)
: Sym(Sym), Result(ToFill) {}
bool HandleBinding(StoreManager &SMgr, Store Store, const MemRegion *R,
SVal Val) override {
SymbolRef SymV = Val.getAsLocSymbol();
if (!SymV || SymV != Sym)
return true;
if (isa<NonParamVarRegion>(R))
Result.emplace_back(R, Val);
return true;
}
};
Bindings getAllVarBindingsForSymbol(ProgramStateManager &Manager,
const ExplodedNode *Node, SymbolRef Sym) {
Bindings Result;
VarBindingsCollector Collector{Sym, Result};
while (Result.empty() && Node) {
Manager.iterBindings(Node->getState(), Collector);
Node = Node->getFirstPred();
}
return Result;
}
namespace {
// Find the first node in the current function context that referred to the
// tracked symbol and the memory location that value was stored to. Note, the
// value is only reported if the allocation occurred in the same function as
// the leak. The function can also return a location context, which should be
// treated as interesting.
struct AllocationInfo {
const ExplodedNode* N;
const MemRegion *R;
const LocationContext *InterestingMethodContext;
AllocationInfo(const ExplodedNode *InN,
const MemRegion *InR,
const LocationContext *InInterestingMethodContext) :
N(InN), R(InR), InterestingMethodContext(InInterestingMethodContext) {}
};
} // end anonymous namespace
static AllocationInfo GetAllocationSite(ProgramStateManager &StateMgr,
const ExplodedNode *N, SymbolRef Sym) {
const ExplodedNode *AllocationNode = N;
const ExplodedNode *AllocationNodeInCurrentOrParentContext = N;
const MemRegion *FirstBinding = nullptr;
const LocationContext *LeakContext = N->getLocationContext();
// The location context of the init method called on the leaked object, if
// available.
const LocationContext *InitMethodContext = nullptr;
while (N) {
ProgramStateRef St = N->getState();
const LocationContext *NContext = N->getLocationContext();
if (!getRefBinding(St, Sym))
break;
StoreManager::FindUniqueBinding FB(Sym);
StateMgr.iterBindings(St, FB);
if (FB) {
const MemRegion *R = FB.getRegion();
// Do not show local variables belonging to a function other than
// where the error is reported.
if (auto MR = dyn_cast<StackSpaceRegion>(R->getMemorySpace()))
if (MR->getStackFrame() == LeakContext->getStackFrame())
FirstBinding = R;
}
// AllocationNode is the last node in which the symbol was tracked.
AllocationNode = N;
// AllocationNodeInCurrentContext, is the last node in the current or
// parent context in which the symbol was tracked.
//
// Note that the allocation site might be in the parent context. For example,
// the case where an allocation happens in a block that captures a reference
// to it and that reference is overwritten/dropped by another call to
// the block.
if (NContext == LeakContext || NContext->isParentOf(LeakContext))
AllocationNodeInCurrentOrParentContext = N;
// Find the last init that was called on the given symbol and store the
// init method's location context.
if (!InitMethodContext)
if (auto CEP = N->getLocation().getAs<CallEnter>()) {
const Stmt *CE = CEP->getCallExpr();
if (const auto *ME = dyn_cast_or_null<ObjCMessageExpr>(CE)) {
const Stmt *RecExpr = ME->getInstanceReceiver();
if (RecExpr) {
SVal RecV = St->getSVal(RecExpr, NContext);
if (ME->getMethodFamily() == OMF_init && RecV.getAsSymbol() == Sym)
InitMethodContext = CEP->getCalleeContext();
}
}
}
N = N->getFirstPred();
}
// If we are reporting a leak of the object that was allocated with alloc,
// mark its init method as interesting.
const LocationContext *InterestingMethodContext = nullptr;
if (InitMethodContext) {
const ProgramPoint AllocPP = AllocationNode->getLocation();
if (Optional<StmtPoint> SP = AllocPP.getAs<StmtPoint>())
if (const ObjCMessageExpr *ME = SP->getStmtAs<ObjCMessageExpr>())
if (ME->getMethodFamily() == OMF_alloc)
InterestingMethodContext = InitMethodContext;
}
// If allocation happened in a function different from the leak node context,
// do not report the binding.
assert(N && "Could not find allocation node");
if (AllocationNodeInCurrentOrParentContext &&
AllocationNodeInCurrentOrParentContext->getLocationContext() !=
LeakContext)
FirstBinding = nullptr;
return AllocationInfo(AllocationNodeInCurrentOrParentContext, FirstBinding,
InterestingMethodContext);
}
PathDiagnosticPieceRef
RefCountReportVisitor::getEndPath(BugReporterContext &BRC,
const ExplodedNode *EndN,
PathSensitiveBugReport &BR) {
BR.markInteresting(Sym);
return BugReporterVisitor::getDefaultEndPath(BRC, EndN, BR);
}
PathDiagnosticPieceRef
RefLeakReportVisitor::getEndPath(BugReporterContext &BRC,
const ExplodedNode *EndN,
PathSensitiveBugReport &BR) {
// Tell the BugReporterContext to report cases when the tracked symbol is
// assigned to different variables, etc.
BR.markInteresting(Sym);
PathDiagnosticLocation L = cast<RefLeakReport>(BR).getEndOfPath();
std::string sbuf;
llvm::raw_string_ostream os(sbuf);
os << "Object leaked: ";
Optional<std::string> RegionDescription = describeRegion(LastBinding);
if (RegionDescription) {
os << "object allocated and stored into '" << *RegionDescription << '\'';
} else {
os << "allocated object of type '" << getPrettyTypeName(Sym->getType())
<< "'";
}
// Get the retain count.
const RefVal *RV = getRefBinding(EndN->getState(), Sym);
assert(RV);
if (RV->getKind() == RefVal::ErrorLeakReturned) {
// FIXME: Per comments in rdar://6320065, "create" only applies to CF
// objects. Only "copy", "alloc", "retain" and "new" transfer ownership
// to the caller for NS objects.
const Decl *D = &EndN->getCodeDecl();
os << (isa<ObjCMethodDecl>(D) ? " is returned from a method "
: " is returned from a function ");
if (D->hasAttr<CFReturnsNotRetainedAttr>()) {
os << "that is annotated as CF_RETURNS_NOT_RETAINED";
} else if (D->hasAttr<NSReturnsNotRetainedAttr>()) {
os << "that is annotated as NS_RETURNS_NOT_RETAINED";
} else if (D->hasAttr<OSReturnsNotRetainedAttr>()) {
os << "that is annotated as OS_RETURNS_NOT_RETAINED";
} else {
if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
if (BRC.getASTContext().getLangOpts().ObjCAutoRefCount) {
os << "managed by Automatic Reference Counting";
} else {
os << "whose name ('" << MD->getSelector().getAsString()
<< "') does not start with "
"'copy', 'mutableCopy', 'alloc' or 'new'."
" This violates the naming convention rules"
" given in the Memory Management Guide for Cocoa";
}
} else {
const FunctionDecl *FD = cast<FunctionDecl>(D);
ObjKind K = RV->getObjKind();
if (K == ObjKind::ObjC || K == ObjKind::CF) {
os << "whose name ('" << *FD
<< "') does not contain 'Copy' or 'Create'. This violates the "
"naming"
" convention rules given in the Memory Management Guide for "
"Core"
" Foundation";
} else if (RV->getObjKind() == ObjKind::OS) {
std::string FuncName = FD->getNameAsString();
os << "whose name ('" << FuncName << "') starts with '"
<< StringRef(FuncName).substr(0, 3) << "'";
}
}
}
} else {
os << " is not referenced later in this execution path and has a retain "
"count of +"
<< RV->getCount();
}
return std::make_shared<PathDiagnosticEventPiece>(L, os.str());
}
RefCountReport::RefCountReport(const RefCountBug &D, const LangOptions &LOpts,
ExplodedNode *n, SymbolRef sym, bool isLeak)
: PathSensitiveBugReport(D, D.getDescription(), n), Sym(sym),
isLeak(isLeak) {
if (!isLeak)
addVisitor<RefCountReportVisitor>(sym);
}
RefCountReport::RefCountReport(const RefCountBug &D, const LangOptions &LOpts,
ExplodedNode *n, SymbolRef sym,
StringRef endText)
: PathSensitiveBugReport(D, D.getDescription(), endText, n) {
addVisitor<RefCountReportVisitor>(sym);
}
void RefLeakReport::deriveParamLocation(CheckerContext &Ctx) {
const SourceManager &SMgr = Ctx.getSourceManager();
if (!Sym->getOriginRegion())
return;
auto *Region = dyn_cast<DeclRegion>(Sym->getOriginRegion());
if (Region) {
const Decl *PDecl = Region->getDecl();
if (isa_and_nonnull<ParmVarDecl>(PDecl)) {
PathDiagnosticLocation ParamLocation =
PathDiagnosticLocation::create(PDecl, SMgr);
Location = ParamLocation;
UniqueingLocation = ParamLocation;
UniqueingDecl = Ctx.getLocationContext()->getDecl();
}
}
}
void RefLeakReport::deriveAllocLocation(CheckerContext &Ctx) {
// Most bug reports are cached at the location where they occurred.
// With leaks, we want to unique them by the location where they were
// allocated, and only report a single path. To do this, we need to find
// the allocation site of a piece of tracked memory, which we do via a
// call to GetAllocationSite. This will walk the ExplodedGraph backwards.
// Note that this is *not* the trimmed graph; we are guaranteed, however,
// that all ancestor nodes that represent the allocation site have the
// same SourceLocation.
const ExplodedNode *AllocNode = nullptr;
const SourceManager &SMgr = Ctx.getSourceManager();
AllocationInfo AllocI =
GetAllocationSite(Ctx.getStateManager(), getErrorNode(), Sym);
AllocNode = AllocI.N;
AllocFirstBinding = AllocI.R;
markInteresting(AllocI.InterestingMethodContext);
// Get the SourceLocation for the allocation site.
// FIXME: This will crash the analyzer if an allocation comes from an
// implicit call (ex: a destructor call).
// (Currently there are no such allocations in Cocoa, though.)
AllocStmt = AllocNode->getStmtForDiagnostics();
if (!AllocStmt) {
AllocFirstBinding = nullptr;
return;
}
PathDiagnosticLocation AllocLocation = PathDiagnosticLocation::createBegin(
AllocStmt, SMgr, AllocNode->getLocationContext());
Location = AllocLocation;
// Set uniqieing info, which will be used for unique the bug reports. The
// leaks should be uniqued on the allocation site.
UniqueingLocation = AllocLocation;
UniqueingDecl = AllocNode->getLocationContext()->getDecl();
}
void RefLeakReport::createDescription(CheckerContext &Ctx) {
assert(Location.isValid() && UniqueingDecl && UniqueingLocation.isValid());
Description.clear();
llvm::raw_string_ostream os(Description);
os << "Potential leak of an object";
Optional<std::string> RegionDescription =
describeRegion(AllocBindingToReport);
if (RegionDescription) {
os << " stored into '" << *RegionDescription << '\'';
} else {
// If we can't figure out the name, just supply the type information.
os << " of type '" << getPrettyTypeName(Sym->getType()) << "'";
}
}
void RefLeakReport::findBindingToReport(CheckerContext &Ctx,
ExplodedNode *Node) {
if (!AllocFirstBinding)
// If we don't have any bindings, we won't be able to find any
// better binding to report.
return;
// If the original region still contains the leaking symbol...
if (Node->getState()->getSVal(AllocFirstBinding).getAsSymbol() == Sym) {
// ...it is the best binding to report.
AllocBindingToReport = AllocFirstBinding;
return;
}
// At this point, we know that the original region doesn't contain the leaking
// when the actual leak happens. It means that it can be confusing for the
// user to see such description in the message.
//
// Let's consider the following example:
// Object *Original = allocate(...);
// Object *New = Original;
// Original = allocate(...);
// Original->release();
//
// Complaining about a leaking object "stored into Original" might cause a
// rightful confusion because 'Original' is actually released.
// We should complain about 'New' instead.
Bindings AllVarBindings =
getAllVarBindingsForSymbol(Ctx.getStateManager(), Node, Sym);
// While looking for the last var bindings, we can still find
// `AllocFirstBinding` to be one of them. In situations like this,
// it would still be the easiest case to explain to our users.
if (!AllVarBindings.empty() &&
llvm::count_if(AllVarBindings,
[this](const std::pair<const MemRegion *, SVal> Binding) {
return Binding.first == AllocFirstBinding;
}) == 0) {
// Let's pick one of them at random (if there is something to pick from).
AllocBindingToReport = AllVarBindings[0].first;
// Because 'AllocBindingToReport' is not the the same as
// 'AllocFirstBinding', we need to explain how the leaking object
// got from one to another.
//
// NOTE: We use the actual SVal stored in AllocBindingToReport here because
// trackStoredValue compares SVal's and it can get trickier for
// something like derived regions if we want to construct SVal from
// Sym. Instead, we take the value that is definitely stored in that
// region, thus guaranteeing that trackStoredValue will work.
bugreporter::trackStoredValue(AllVarBindings[0].second.castAs<KnownSVal>(),
AllocBindingToReport, *this);
} else {
AllocBindingToReport = AllocFirstBinding;
}
}
RefLeakReport::RefLeakReport(const RefCountBug &D, const LangOptions &LOpts,
ExplodedNode *N, SymbolRef Sym,
CheckerContext &Ctx)
: RefCountReport(D, LOpts, N, Sym, /*isLeak=*/true) {
deriveAllocLocation(Ctx);
findBindingToReport(Ctx, N);
if (!AllocFirstBinding)
deriveParamLocation(Ctx);
createDescription(Ctx);
addVisitor<RefLeakReportVisitor>(Sym, AllocBindingToReport);
}
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