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