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//===- ObjCSuperDeallocChecker.cpp - Check correct use of [super dealloc] -===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This defines ObjCSuperDeallocChecker, a builtin check that warns when
// self is used after a call to [super dealloc] in MRR mode.
//
//===----------------------------------------------------------------------===//
#include "ClangSACheckers.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
using namespace clang;
using namespace ento;
namespace {
class ObjCSuperDeallocChecker
: public Checker<check::PostObjCMessage, check::PreObjCMessage,
check::PreCall, check::Location> {
mutable IdentifierInfo *IIdealloc, *IINSObject;
mutable Selector SELdealloc;
std::unique_ptr<BugType> DoubleSuperDeallocBugType;
void initIdentifierInfoAndSelectors(ASTContext &Ctx) const;
bool isSuperDeallocMessage(const ObjCMethodCall &M) const;
public:
ObjCSuperDeallocChecker();
void checkPostObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const;
void checkPreObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const;
void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
void checkLocation(SVal l, bool isLoad, const Stmt *S,
CheckerContext &C) const;
private:
void diagnoseCallArguments(const CallEvent &CE, CheckerContext &C) const;
void reportUseAfterDealloc(SymbolRef Sym, StringRef Desc, const Stmt *S,
CheckerContext &C) const;
};
} // End anonymous namespace.
// Remember whether [super dealloc] has previously been called on the
// SymbolRef for the receiver.
REGISTER_SET_WITH_PROGRAMSTATE(CalledSuperDealloc, SymbolRef)
namespace {
class SuperDeallocBRVisitor final : public BugReporterVisitor {
SymbolRef ReceiverSymbol;
bool Satisfied;
public:
SuperDeallocBRVisitor(SymbolRef ReceiverSymbol)
: ReceiverSymbol(ReceiverSymbol),
Satisfied(false) {}
std::shared_ptr<PathDiagnosticPiece> VisitNode(const ExplodedNode *Succ,
const ExplodedNode *Pred,
BugReporterContext &BRC,
BugReport &BR) override;
void Profile(llvm::FoldingSetNodeID &ID) const override {
ID.Add(ReceiverSymbol);
}
};
} // End anonymous namespace.
void ObjCSuperDeallocChecker::checkPreObjCMessage(const ObjCMethodCall &M,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
SymbolRef ReceiverSymbol = M.getReceiverSVal().getAsSymbol();
if (!ReceiverSymbol) {
diagnoseCallArguments(M, C);
return;
}
bool AlreadyCalled = State->contains<CalledSuperDealloc>(ReceiverSymbol);
if (!AlreadyCalled)
return;
StringRef Desc;
if (isSuperDeallocMessage(M)) {
Desc = "[super dealloc] should not be called multiple times";
} else {
Desc = StringRef();
}
reportUseAfterDealloc(ReceiverSymbol, Desc, M.getOriginExpr(), C);
}
void ObjCSuperDeallocChecker::checkPreCall(const CallEvent &Call,
CheckerContext &C) const {
diagnoseCallArguments(Call, C);
}
void ObjCSuperDeallocChecker::checkPostObjCMessage(const ObjCMethodCall &M,
CheckerContext &C) const {
// Check for [super dealloc] method call.
if (!isSuperDeallocMessage(M))
return;
ProgramStateRef State = C.getState();
SymbolRef ReceiverSymbol = M.getSelfSVal().getAsSymbol();
assert(ReceiverSymbol && "No receiver symbol at call to [super dealloc]?");
// We add this transition in checkPostObjCMessage to avoid warning when
// we inline a call to [super dealloc] where the inlined call itself
// calls [super dealloc].
State = State->add<CalledSuperDealloc>(ReceiverSymbol);
C.addTransition(State);
}
void ObjCSuperDeallocChecker::checkLocation(SVal L, bool IsLoad, const Stmt *S,
CheckerContext &C) const {
SymbolRef BaseSym = L.getLocSymbolInBase();
if (!BaseSym)
return;
ProgramStateRef State = C.getState();
if (!State->contains<CalledSuperDealloc>(BaseSym))
return;
const MemRegion *R = L.getAsRegion();
if (!R)
return;
// Climb the super regions to find the base symbol while recording
// the second-to-last region for error reporting.
const MemRegion *PriorSubRegion = nullptr;
while (const SubRegion *SR = dyn_cast<SubRegion>(R)) {
if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(SR)) {
BaseSym = SymR->getSymbol();
break;
} else {
R = SR->getSuperRegion();
PriorSubRegion = SR;
}
}
StringRef Desc = StringRef();
auto *IvarRegion = dyn_cast_or_null<ObjCIvarRegion>(PriorSubRegion);
std::string Buf;
llvm::raw_string_ostream OS(Buf);
if (IvarRegion) {
OS << "Use of instance variable '" << *IvarRegion->getDecl() <<
"' after 'self' has been deallocated";
Desc = OS.str();
}
reportUseAfterDealloc(BaseSym, Desc, S, C);
}
/// Report a use-after-dealloc on Sym. If not empty,
/// Desc will be used to describe the error; otherwise,
/// a default warning will be used.
void ObjCSuperDeallocChecker::reportUseAfterDealloc(SymbolRef Sym,
StringRef Desc,
const Stmt *S,
CheckerContext &C) const {
// We have a use of self after free.
// This likely causes a crash, so stop exploring the
// path by generating a sink.
ExplodedNode *ErrNode = C.generateErrorNode();
// If we've already reached this node on another path, return.
if (!ErrNode)
return;
if (Desc.empty())
Desc = "Use of 'self' after it has been deallocated";
// Generate the report.
std::unique_ptr<BugReport> BR(
new BugReport(*DoubleSuperDeallocBugType, Desc, ErrNode));
BR->addRange(S->getSourceRange());
BR->addVisitor(llvm::make_unique<SuperDeallocBRVisitor>(Sym));
C.emitReport(std::move(BR));
}
/// Diagnose if any of the arguments to CE have already been
/// dealloc'd.
void ObjCSuperDeallocChecker::diagnoseCallArguments(const CallEvent &CE,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
unsigned ArgCount = CE.getNumArgs();
for (unsigned I = 0; I < ArgCount; I++) {
SymbolRef Sym = CE.getArgSVal(I).getAsSymbol();
if (!Sym)
continue;
if (State->contains<CalledSuperDealloc>(Sym)) {
reportUseAfterDealloc(Sym, StringRef(), CE.getArgExpr(I), C);
return;
}
}
}
ObjCSuperDeallocChecker::ObjCSuperDeallocChecker()
: IIdealloc(nullptr), IINSObject(nullptr) {
DoubleSuperDeallocBugType.reset(
new BugType(this, "[super dealloc] should not be called more than once",
categories::CoreFoundationObjectiveC));
}
void
ObjCSuperDeallocChecker::initIdentifierInfoAndSelectors(ASTContext &Ctx) const {
if (IIdealloc)
return;
IIdealloc = &Ctx.Idents.get("dealloc");
IINSObject = &Ctx.Idents.get("NSObject");
SELdealloc = Ctx.Selectors.getSelector(0, &IIdealloc);
}
bool
ObjCSuperDeallocChecker::isSuperDeallocMessage(const ObjCMethodCall &M) const {
if (M.getOriginExpr()->getReceiverKind() != ObjCMessageExpr::SuperInstance)
return false;
ASTContext &Ctx = M.getState()->getStateManager().getContext();
initIdentifierInfoAndSelectors(Ctx);
return M.getSelector() == SELdealloc;
}
std::shared_ptr<PathDiagnosticPiece>
SuperDeallocBRVisitor::VisitNode(const ExplodedNode *Succ,
const ExplodedNode *Pred,
BugReporterContext &BRC, BugReport &BR) {
if (Satisfied)
return nullptr;
ProgramStateRef State = Succ->getState();
bool CalledNow =
Succ->getState()->contains<CalledSuperDealloc>(ReceiverSymbol);
bool CalledBefore =
Pred->getState()->contains<CalledSuperDealloc>(ReceiverSymbol);
// Is Succ the node on which the analyzer noted that [super dealloc] was
// called on ReceiverSymbol?
if (CalledNow && !CalledBefore) {
Satisfied = true;
ProgramPoint P = Succ->getLocation();
PathDiagnosticLocation L =
PathDiagnosticLocation::create(P, BRC.getSourceManager());
if (!L.isValid() || !L.asLocation().isValid())
return nullptr;
return std::make_shared<PathDiagnosticEventPiece>(
L, "[super dealloc] called here");
}
return nullptr;
}
//===----------------------------------------------------------------------===//
// Checker Registration.
//===----------------------------------------------------------------------===//
void ento::registerObjCSuperDeallocChecker(CheckerManager &Mgr) {
const LangOptions &LangOpts = Mgr.getLangOpts();
if (LangOpts.getGC() == LangOptions::GCOnly || LangOpts.ObjCAutoRefCount)
return;
Mgr.registerChecker<ObjCSuperDeallocChecker>();
}