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Diffstat (limited to 'clang/lib/StaticAnalyzer/Checkers/CallAndMessageChecker.cpp')
| -rw-r--r-- | clang/lib/StaticAnalyzer/Checkers/CallAndMessageChecker.cpp | 385 |
1 files changed, 385 insertions, 0 deletions
diff --git a/clang/lib/StaticAnalyzer/Checkers/CallAndMessageChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CallAndMessageChecker.cpp new file mode 100644 index 0000000..f601431 --- /dev/null +++ b/clang/lib/StaticAnalyzer/Checkers/CallAndMessageChecker.cpp @@ -0,0 +1,385 @@ +//===--- CallAndMessageChecker.cpp ------------------------------*- C++ -*--==// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This defines CallAndMessageChecker, a builtin checker that checks for various +// errors of call and objc message expressions. +// +//===----------------------------------------------------------------------===// + +#include "ClangSACheckers.h" +#include "clang/StaticAnalyzer/Core/Checker.h" +#include "clang/StaticAnalyzer/Core/CheckerManager.h" +#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" +#include "clang/StaticAnalyzer/Core/PathSensitive/ObjCMessage.h" +#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" +#include "clang/AST/ParentMap.h" +#include "clang/Basic/TargetInfo.h" +#include "llvm/ADT/SmallString.h" + +using namespace clang; +using namespace ento; + +namespace { +class CallAndMessageChecker + : public Checker< check::PreStmt<CallExpr>, check::PreObjCMessage > { + mutable OwningPtr<BugType> BT_call_null; + mutable OwningPtr<BugType> BT_call_undef; + mutable OwningPtr<BugType> BT_call_arg; + mutable OwningPtr<BugType> BT_msg_undef; + mutable OwningPtr<BugType> BT_objc_prop_undef; + mutable OwningPtr<BugType> BT_msg_arg; + mutable OwningPtr<BugType> BT_msg_ret; +public: + + void checkPreStmt(const CallExpr *CE, CheckerContext &C) const; + void checkPreObjCMessage(ObjCMessage msg, CheckerContext &C) const; + +private: + static void PreVisitProcessArgs(CheckerContext &C,CallOrObjCMessage callOrMsg, + const char *BT_desc, OwningPtr<BugType> &BT); + static bool PreVisitProcessArg(CheckerContext &C, SVal V,SourceRange argRange, + const Expr *argEx, + const bool checkUninitFields, + const char *BT_desc, + OwningPtr<BugType> &BT); + + static void EmitBadCall(BugType *BT, CheckerContext &C, const CallExpr *CE); + void emitNilReceiverBug(CheckerContext &C, const ObjCMessage &msg, + ExplodedNode *N) const; + + void HandleNilReceiver(CheckerContext &C, + ProgramStateRef state, + ObjCMessage msg) const; + + static void LazyInit_BT(const char *desc, OwningPtr<BugType> &BT) { + if (!BT) + BT.reset(new BuiltinBug(desc)); + } +}; +} // end anonymous namespace + +void CallAndMessageChecker::EmitBadCall(BugType *BT, CheckerContext &C, + const CallExpr *CE) { + ExplodedNode *N = C.generateSink(); + if (!N) + return; + + BugReport *R = new BugReport(*BT, BT->getName(), N); + R->addVisitor(bugreporter::getTrackNullOrUndefValueVisitor(N, + bugreporter::GetCalleeExpr(N), R)); + C.EmitReport(R); +} + +void CallAndMessageChecker::PreVisitProcessArgs(CheckerContext &C, + CallOrObjCMessage callOrMsg, + const char *BT_desc, + OwningPtr<BugType> &BT) { + // Don't check for uninitialized field values in arguments if the + // caller has a body that is available and we have the chance to inline it. + // This is a hack, but is a reasonable compromise betweens sometimes warning + // and sometimes not depending on if we decide to inline a function. + const Decl *D = callOrMsg.getDecl(); + const bool checkUninitFields = + !(C.getAnalysisManager().shouldInlineCall() && + (D && D->getBody())); + + for (unsigned i = 0, e = callOrMsg.getNumArgs(); i != e; ++i) + if (PreVisitProcessArg(C, callOrMsg.getArgSVal(i), + callOrMsg.getArgSourceRange(i), callOrMsg.getArg(i), + checkUninitFields, + BT_desc, BT)) + return; +} + +bool CallAndMessageChecker::PreVisitProcessArg(CheckerContext &C, + SVal V, SourceRange argRange, + const Expr *argEx, + const bool checkUninitFields, + const char *BT_desc, + OwningPtr<BugType> &BT) { + if (V.isUndef()) { + if (ExplodedNode *N = C.generateSink()) { + LazyInit_BT(BT_desc, BT); + + // Generate a report for this bug. + BugReport *R = new BugReport(*BT, BT->getName(), N); + R->addRange(argRange); + if (argEx) + R->addVisitor(bugreporter::getTrackNullOrUndefValueVisitor(N, argEx, + R)); + C.EmitReport(R); + } + return true; + } + + if (!checkUninitFields) + return false; + + if (const nonloc::LazyCompoundVal *LV = + dyn_cast<nonloc::LazyCompoundVal>(&V)) { + + class FindUninitializedField { + public: + SmallVector<const FieldDecl *, 10> FieldChain; + private: + ASTContext &C; + StoreManager &StoreMgr; + MemRegionManager &MrMgr; + Store store; + public: + FindUninitializedField(ASTContext &c, StoreManager &storeMgr, + MemRegionManager &mrMgr, Store s) + : C(c), StoreMgr(storeMgr), MrMgr(mrMgr), store(s) {} + + bool Find(const TypedValueRegion *R) { + QualType T = R->getValueType(); + if (const RecordType *RT = T->getAsStructureType()) { + const RecordDecl *RD = RT->getDecl()->getDefinition(); + assert(RD && "Referred record has no definition"); + for (RecordDecl::field_iterator I = + RD->field_begin(), E = RD->field_end(); I!=E; ++I) { + const FieldRegion *FR = MrMgr.getFieldRegion(*I, R); + FieldChain.push_back(*I); + T = (*I)->getType(); + if (T->getAsStructureType()) { + if (Find(FR)) + return true; + } + else { + const SVal &V = StoreMgr.getBinding(store, loc::MemRegionVal(FR)); + if (V.isUndef()) + return true; + } + FieldChain.pop_back(); + } + } + + return false; + } + }; + + const LazyCompoundValData *D = LV->getCVData(); + FindUninitializedField F(C.getASTContext(), + C.getState()->getStateManager().getStoreManager(), + C.getSValBuilder().getRegionManager(), + D->getStore()); + + if (F.Find(D->getRegion())) { + if (ExplodedNode *N = C.generateSink()) { + LazyInit_BT(BT_desc, BT); + SmallString<512> Str; + llvm::raw_svector_ostream os(Str); + os << "Passed-by-value struct argument contains uninitialized data"; + + if (F.FieldChain.size() == 1) + os << " (e.g., field: '" << *F.FieldChain[0] << "')"; + else { + os << " (e.g., via the field chain: '"; + bool first = true; + for (SmallVectorImpl<const FieldDecl *>::iterator + DI = F.FieldChain.begin(), DE = F.FieldChain.end(); DI!=DE;++DI){ + if (first) + first = false; + else + os << '.'; + os << **DI; + } + os << "')"; + } + + // Generate a report for this bug. + BugReport *R = new BugReport(*BT, os.str(), N); + R->addRange(argRange); + + // FIXME: enhance track back for uninitialized value for arbitrary + // memregions + C.EmitReport(R); + } + return true; + } + } + + return false; +} + +void CallAndMessageChecker::checkPreStmt(const CallExpr *CE, + CheckerContext &C) const{ + + const Expr *Callee = CE->getCallee()->IgnoreParens(); + const LocationContext *LCtx = C.getLocationContext(); + SVal L = C.getState()->getSVal(Callee, LCtx); + + if (L.isUndef()) { + if (!BT_call_undef) + BT_call_undef.reset(new BuiltinBug("Called function pointer is an " + "uninitalized pointer value")); + EmitBadCall(BT_call_undef.get(), C, CE); + return; + } + + if (isa<loc::ConcreteInt>(L)) { + if (!BT_call_null) + BT_call_null.reset( + new BuiltinBug("Called function pointer is null (null dereference)")); + EmitBadCall(BT_call_null.get(), C, CE); + } + + PreVisitProcessArgs(C, CallOrObjCMessage(CE, C.getState(), LCtx), + "Function call argument is an uninitialized value", + BT_call_arg); +} + +void CallAndMessageChecker::checkPreObjCMessage(ObjCMessage msg, + CheckerContext &C) const { + + ProgramStateRef state = C.getState(); + const LocationContext *LCtx = C.getLocationContext(); + + // FIXME: Handle 'super'? + if (const Expr *receiver = msg.getInstanceReceiver()) { + SVal recVal = state->getSVal(receiver, LCtx); + if (recVal.isUndef()) { + if (ExplodedNode *N = C.generateSink()) { + BugType *BT = 0; + if (msg.isPureMessageExpr()) { + if (!BT_msg_undef) + BT_msg_undef.reset(new BuiltinBug("Receiver in message expression " + "is an uninitialized value")); + BT = BT_msg_undef.get(); + } + else { + if (!BT_objc_prop_undef) + BT_objc_prop_undef.reset(new BuiltinBug("Property access on an " + "uninitialized object pointer")); + BT = BT_objc_prop_undef.get(); + } + BugReport *R = + new BugReport(*BT, BT->getName(), N); + R->addRange(receiver->getSourceRange()); + R->addVisitor(bugreporter::getTrackNullOrUndefValueVisitor(N, + receiver, + R)); + C.EmitReport(R); + } + return; + } else { + // Bifurcate the state into nil and non-nil ones. + DefinedOrUnknownSVal receiverVal = cast<DefinedOrUnknownSVal>(recVal); + + ProgramStateRef notNilState, nilState; + llvm::tie(notNilState, nilState) = state->assume(receiverVal); + + // Handle receiver must be nil. + if (nilState && !notNilState) { + HandleNilReceiver(C, state, msg); + return; + } + } + } + + const char *bugDesc = msg.isPropertySetter() ? + "Argument for property setter is an uninitialized value" + : "Argument in message expression is an uninitialized value"; + // Check for any arguments that are uninitialized/undefined. + PreVisitProcessArgs(C, CallOrObjCMessage(msg, state, LCtx), + bugDesc, BT_msg_arg); +} + +void CallAndMessageChecker::emitNilReceiverBug(CheckerContext &C, + const ObjCMessage &msg, + ExplodedNode *N) const { + + if (!BT_msg_ret) + BT_msg_ret.reset( + new BuiltinBug("Receiver in message expression is " + "'nil' and returns a garbage value")); + + SmallString<200> buf; + llvm::raw_svector_ostream os(buf); + os << "The receiver of message '" << msg.getSelector().getAsString() + << "' is nil and returns a value of type '" + << msg.getType(C.getASTContext()).getAsString() << "' that will be garbage"; + + BugReport *report = new BugReport(*BT_msg_ret, os.str(), N); + if (const Expr *receiver = msg.getInstanceReceiver()) { + report->addRange(receiver->getSourceRange()); + report->addVisitor(bugreporter::getTrackNullOrUndefValueVisitor(N, + receiver, + report)); + } + C.EmitReport(report); +} + +static bool supportsNilWithFloatRet(const llvm::Triple &triple) { + return (triple.getVendor() == llvm::Triple::Apple && + (triple.getOS() == llvm::Triple::IOS || + !triple.isMacOSXVersionLT(10,5))); +} + +void CallAndMessageChecker::HandleNilReceiver(CheckerContext &C, + ProgramStateRef state, + ObjCMessage msg) const { + ASTContext &Ctx = C.getASTContext(); + + // Check the return type of the message expression. A message to nil will + // return different values depending on the return type and the architecture. + QualType RetTy = msg.getType(Ctx); + CanQualType CanRetTy = Ctx.getCanonicalType(RetTy); + const LocationContext *LCtx = C.getLocationContext(); + + if (CanRetTy->isStructureOrClassType()) { + // Structure returns are safe since the compiler zeroes them out. + SVal V = C.getSValBuilder().makeZeroVal(msg.getType(Ctx)); + C.addTransition(state->BindExpr(msg.getMessageExpr(), LCtx, V)); + return; + } + + // Other cases: check if sizeof(return type) > sizeof(void*) + if (CanRetTy != Ctx.VoidTy && C.getLocationContext()->getParentMap() + .isConsumedExpr(msg.getMessageExpr())) { + // Compute: sizeof(void *) and sizeof(return type) + const uint64_t voidPtrSize = Ctx.getTypeSize(Ctx.VoidPtrTy); + const uint64_t returnTypeSize = Ctx.getTypeSize(CanRetTy); + + if (voidPtrSize < returnTypeSize && + !(supportsNilWithFloatRet(Ctx.getTargetInfo().getTriple()) && + (Ctx.FloatTy == CanRetTy || + Ctx.DoubleTy == CanRetTy || + Ctx.LongDoubleTy == CanRetTy || + Ctx.LongLongTy == CanRetTy || + Ctx.UnsignedLongLongTy == CanRetTy))) { + if (ExplodedNode *N = C.generateSink(state)) + emitNilReceiverBug(C, msg, N); + return; + } + + // Handle the safe cases where the return value is 0 if the + // receiver is nil. + // + // FIXME: For now take the conservative approach that we only + // return null values if we *know* that the receiver is nil. + // This is because we can have surprises like: + // + // ... = [[NSScreens screens] objectAtIndex:0]; + // + // What can happen is that [... screens] could return nil, but + // it most likely isn't nil. We should assume the semantics + // of this case unless we have *a lot* more knowledge. + // + SVal V = C.getSValBuilder().makeZeroVal(msg.getType(Ctx)); + C.addTransition(state->BindExpr(msg.getMessageExpr(), LCtx, V)); + return; + } + + C.addTransition(state); +} + +void ento::registerCallAndMessageChecker(CheckerManager &mgr) { + mgr.registerChecker<CallAndMessageChecker>(); +} |