//===--- 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/AST/ParentMap.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/Support/raw_ostream.h"
using namespace clang;
using namespace ento;
namespace {
struct ChecksFilter {
DefaultBool Check_CallAndMessageUnInitRefArg;
DefaultBool Check_CallAndMessageChecker;
CheckName CheckName_CallAndMessageUnInitRefArg;
CheckName CheckName_CallAndMessageChecker;
};
class CallAndMessageChecker
: public Checker< check::PreStmt<CallExpr>,
check::PreStmt<CXXDeleteExpr>,
check::PreObjCMessage,
check::ObjCMessageNil,
check::PreCall > {
mutable std::unique_ptr<BugType> BT_call_null;
mutable std::unique_ptr<BugType> BT_call_undef;
mutable std::unique_ptr<BugType> BT_cxx_call_null;
mutable std::unique_ptr<BugType> BT_cxx_call_undef;
mutable std::unique_ptr<BugType> BT_call_arg;
mutable std::unique_ptr<BugType> BT_cxx_delete_undef;
mutable std::unique_ptr<BugType> BT_msg_undef;
mutable std::unique_ptr<BugType> BT_objc_prop_undef;
mutable std::unique_ptr<BugType> BT_objc_subscript_undef;
mutable std::unique_ptr<BugType> BT_msg_arg;
mutable std::unique_ptr<BugType> BT_msg_ret;
mutable std::unique_ptr<BugType> BT_call_few_args;
public:
ChecksFilter Filter;
void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
void checkPreStmt(const CXXDeleteExpr *DE, CheckerContext &C) const;
void checkPreObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;
/// Fill in the return value that results from messaging nil based on the
/// return type and architecture and diagnose if the return value will be
/// garbage.
void checkObjCMessageNil(const ObjCMethodCall &msg, CheckerContext &C) const;
void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
private:
bool PreVisitProcessArg(CheckerContext &C, SVal V, SourceRange ArgRange,
const Expr *ArgEx, bool IsFirstArgument,
bool CheckUninitFields, const CallEvent &Call,
std::unique_ptr<BugType> &BT,
const ParmVarDecl *ParamDecl) const;
static void emitBadCall(BugType *BT, CheckerContext &C, const Expr *BadE);
void emitNilReceiverBug(CheckerContext &C, const ObjCMethodCall &msg,
ExplodedNode *N) const;
void HandleNilReceiver(CheckerContext &C,
ProgramStateRef state,
const ObjCMethodCall &msg) const;
void LazyInit_BT(const char *desc, std::unique_ptr<BugType> &BT) const {
if (!BT)
BT.reset(new BuiltinBug(this, desc));
}
bool uninitRefOrPointer(CheckerContext &C, const SVal &V,
SourceRange ArgRange,
const Expr *ArgEx, std::unique_ptr<BugType> &BT,
const ParmVarDecl *ParamDecl, const char *BD) const;
};
} // end anonymous namespace
void CallAndMessageChecker::emitBadCall(BugType *BT, CheckerContext &C,
const Expr *BadE) {
ExplodedNode *N = C.generateErrorNode();
if (!N)
return;
auto R = llvm::make_unique<BugReport>(*BT, BT->getName(), N);
if (BadE) {
R->addRange(BadE->getSourceRange());
if (BadE->isGLValue())
BadE = bugreporter::getDerefExpr(BadE);
bugreporter::trackNullOrUndefValue(N, BadE, *R);
}
C.emitReport(std::move(R));
}
static StringRef describeUninitializedArgumentInCall(const CallEvent &Call,
bool IsFirstArgument) {
switch (Call.getKind()) {
case CE_ObjCMessage: {
const ObjCMethodCall &Msg = cast<ObjCMethodCall>(Call);
switch (Msg.getMessageKind()) {
case OCM_Message:
return "Argument in message expression is an uninitialized value";
case OCM_PropertyAccess:
assert(Msg.isSetter() && "Getters have no args");
return "Argument for property setter is an uninitialized value";
case OCM_Subscript:
if (Msg.isSetter() && IsFirstArgument)
return "Argument for subscript setter is an uninitialized value";
return "Subscript index is an uninitialized value";
}
llvm_unreachable("Unknown message kind.");
}
case CE_Block:
return "Block call argument is an uninitialized value";
default:
return "Function call argument is an uninitialized value";
}
}
bool CallAndMessageChecker::uninitRefOrPointer(CheckerContext &C,
const SVal &V,
SourceRange ArgRange,
const Expr *ArgEx,
std::unique_ptr<BugType> &BT,
const ParmVarDecl *ParamDecl,
const char *BD) const {
if (!Filter.Check_CallAndMessageUnInitRefArg)
return false;
// No parameter declaration available, i.e. variadic function argument.
if(!ParamDecl)
return false;
// If parameter is declared as pointer to const in function declaration,
// then check if corresponding argument in function call is
// pointing to undefined symbol value (uninitialized memory).
StringRef Message;
if (ParamDecl->getType()->isPointerType()) {
Message = "Function call argument is a pointer to uninitialized value";
} else if (ParamDecl->getType()->isReferenceType()) {
Message = "Function call argument is an uninitialized value";
} else
return false;
if(!ParamDecl->getType()->getPointeeType().isConstQualified())
return false;
if (const MemRegion *SValMemRegion = V.getAsRegion()) {
const ProgramStateRef State = C.getState();
const SVal PSV = State->getSVal(SValMemRegion);
if (PSV.isUndef()) {
if (ExplodedNode *N = C.generateErrorNode()) {
LazyInit_BT(BD, BT);
auto R = llvm::make_unique<BugReport>(*BT, Message, N);
R->addRange(ArgRange);
if (ArgEx) {
bugreporter::trackNullOrUndefValue(N, ArgEx, *R);
}
C.emitReport(std::move(R));
}
return true;
}
}
return false;
}
bool CallAndMessageChecker::PreVisitProcessArg(CheckerContext &C,
SVal V,
SourceRange ArgRange,
const Expr *ArgEx,
bool IsFirstArgument,
bool CheckUninitFields,
const CallEvent &Call,
std::unique_ptr<BugType> &BT,
const ParmVarDecl *ParamDecl
) const {
const char *BD = "Uninitialized argument value";
if (uninitRefOrPointer(C, V, ArgRange, ArgEx, BT, ParamDecl, BD))
return true;
if (V.isUndef()) {
if (ExplodedNode *N = C.generateErrorNode()) {
LazyInit_BT(BD, BT);
// Generate a report for this bug.
StringRef Desc =
describeUninitializedArgumentInCall(Call, IsFirstArgument);
auto R = llvm::make_unique<BugReport>(*BT, Desc, N);
R->addRange(ArgRange);
if (ArgEx)
bugreporter::trackNullOrUndefValue(N, ArgEx, *R);
C.emitReport(std::move(R));
}
return true;
}
if (!CheckUninitFields)
return false;
if (Optional<nonloc::LazyCompoundVal> LV =
V.getAs<nonloc::LazyCompoundVal>()) {
class FindUninitializedField {
public:
SmallVector<const FieldDecl *, 10> FieldChain;
private:
StoreManager &StoreMgr;
MemRegionManager &MrMgr;
Store store;
public:
FindUninitializedField(StoreManager &storeMgr,
MemRegionManager &mrMgr, Store s)
: 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 (const auto *I : RD->fields()) {
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.getState()->getStateManager().getStoreManager(),
C.getSValBuilder().getRegionManager(),
D->getStore());
if (F.Find(D->getRegion())) {
if (ExplodedNode *N = C.generateErrorNode()) {
LazyInit_BT(BD, 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.
auto R = llvm::make_unique<BugReport>(*BT, os.str(), N);
R->addRange(ArgRange);
// FIXME: enhance track back for uninitialized value for arbitrary
// memregions
C.emitReport(std::move(R));
}
return true;
}
}
return false;
}
void CallAndMessageChecker::checkPreStmt(const CallExpr *CE,
CheckerContext &C) const{
const Expr *Callee = CE->getCallee()->IgnoreParens();
ProgramStateRef State = C.getState();
const LocationContext *LCtx = C.getLocationContext();
SVal L = State->getSVal(Callee, LCtx);
if (L.isUndef()) {
if (!BT_call_undef)
BT_call_undef.reset(new BuiltinBug(
this, "Called function pointer is an uninitialized pointer value"));
emitBadCall(BT_call_undef.get(), C, Callee);
return;
}
ProgramStateRef StNonNull, StNull;
std::tie(StNonNull, StNull) = State->assume(L.castAs<DefinedOrUnknownSVal>());
if (StNull && !StNonNull) {
if (!BT_call_null)
BT_call_null.reset(new BuiltinBug(
this, "Called function pointer is null (null dereference)"));
emitBadCall(BT_call_null.get(), C, Callee);
return;
}
C.addTransition(StNonNull);
}
void CallAndMessageChecker::checkPreStmt(const CXXDeleteExpr *DE,
CheckerContext &C) const {
SVal Arg = C.getSVal(DE->getArgument());
if (Arg.isUndef()) {
StringRef Desc;
ExplodedNode *N = C.generateErrorNode();
if (!N)
return;
if (!BT_cxx_delete_undef)
BT_cxx_delete_undef.reset(
new BuiltinBug(this, "Uninitialized argument value"));
if (DE->isArrayFormAsWritten())
Desc = "Argument to 'delete[]' is uninitialized";
else
Desc = "Argument to 'delete' is uninitialized";
BugType *BT = BT_cxx_delete_undef.get();
auto R = llvm::make_unique<BugReport>(*BT, Desc, N);
bugreporter::trackNullOrUndefValue(N, DE, *R);
C.emitReport(std::move(R));
return;
}
}
void CallAndMessageChecker::checkPreCall(const CallEvent &Call,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
// If this is a call to a C++ method, check if the callee is null or
// undefined.
if (const CXXInstanceCall *CC = dyn_cast<CXXInstanceCall>(&Call)) {
SVal V = CC->getCXXThisVal();
if (V.isUndef()) {
if (!BT_cxx_call_undef)
BT_cxx_call_undef.reset(
new BuiltinBug(this, "Called C++ object pointer is uninitialized"));
emitBadCall(BT_cxx_call_undef.get(), C, CC->getCXXThisExpr());
return;
}
ProgramStateRef StNonNull, StNull;
std::tie(StNonNull, StNull) =
State->assume(V.castAs<DefinedOrUnknownSVal>());
if (StNull && !StNonNull) {
if (!BT_cxx_call_null)
BT_cxx_call_null.reset(
new BuiltinBug(this, "Called C++ object pointer is null"));
emitBadCall(BT_cxx_call_null.get(), C, CC->getCXXThisExpr());
return;
}
State = StNonNull;
}
const Decl *D = Call.getDecl();
const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D);
if (FD) {
// If we have a declaration, we can make sure we pass enough parameters to
// the function.
unsigned Params = FD->getNumParams();
if (Call.getNumArgs() < Params) {
ExplodedNode *N = C.generateErrorNode();
if (!N)
return;
LazyInit_BT("Function call with too few arguments", BT_call_few_args);
SmallString<512> Str;
llvm::raw_svector_ostream os(Str);
os << "Function taking " << Params << " argument"
<< (Params == 1 ? "" : "s") << " is called with less ("
<< Call.getNumArgs() << ")";
C.emitReport(
llvm::make_unique<BugReport>(*BT_call_few_args, os.str(), N));
}
}
// 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 bool checkUninitFields =
!(C.getAnalysisManager().shouldInlineCall() && (D && D->getBody()));
std::unique_ptr<BugType> *BT;
if (isa<ObjCMethodCall>(Call))
BT = &BT_msg_arg;
else
BT = &BT_call_arg;
for (unsigned i = 0, e = Call.getNumArgs(); i != e; ++i) {
const ParmVarDecl *ParamDecl = nullptr;
if(FD && i < FD->getNumParams())
ParamDecl = FD->getParamDecl(i);
if (PreVisitProcessArg(C, Call.getArgSVal(i), Call.getArgSourceRange(i),
Call.getArgExpr(i), /*IsFirstArgument=*/i == 0,
checkUninitFields, Call, *BT, ParamDecl))
return;
}
// If we make it here, record our assumptions about the callee.
C.addTransition(State);
}
void CallAndMessageChecker::checkPreObjCMessage(const ObjCMethodCall &msg,
CheckerContext &C) const {
SVal recVal = msg.getReceiverSVal();
if (recVal.isUndef()) {
if (ExplodedNode *N = C.generateErrorNode()) {
BugType *BT = nullptr;
switch (msg.getMessageKind()) {
case OCM_Message:
if (!BT_msg_undef)
BT_msg_undef.reset(new BuiltinBug(this,
"Receiver in message expression "
"is an uninitialized value"));
BT = BT_msg_undef.get();
break;
case OCM_PropertyAccess:
if (!BT_objc_prop_undef)
BT_objc_prop_undef.reset(new BuiltinBug(
this, "Property access on an uninitialized object pointer"));
BT = BT_objc_prop_undef.get();
break;
case OCM_Subscript:
if (!BT_objc_subscript_undef)
BT_objc_subscript_undef.reset(new BuiltinBug(
this, "Subscript access on an uninitialized object pointer"));
BT = BT_objc_subscript_undef.get();
break;
}
assert(BT && "Unknown message kind.");
auto R = llvm::make_unique<BugReport>(*BT, BT->getName(), N);
const ObjCMessageExpr *ME = msg.getOriginExpr();
R->addRange(ME->getReceiverRange());
// FIXME: getTrackNullOrUndefValueVisitor can't handle "super" yet.
if (const Expr *ReceiverE = ME->getInstanceReceiver())
bugreporter::trackNullOrUndefValue(N, ReceiverE, *R);
C.emitReport(std::move(R));
}
return;
}
}
void CallAndMessageChecker::checkObjCMessageNil(const ObjCMethodCall &msg,
CheckerContext &C) const {
HandleNilReceiver(C, C.getState(), msg);
}
void CallAndMessageChecker::emitNilReceiverBug(CheckerContext &C,
const ObjCMethodCall &msg,
ExplodedNode *N) const {
if (!BT_msg_ret)
BT_msg_ret.reset(
new BuiltinBug(this, "Receiver in message expression is 'nil'"));
const ObjCMessageExpr *ME = msg.getOriginExpr();
QualType ResTy = msg.getResultType();
SmallString<200> buf;
llvm::raw_svector_ostream os(buf);
os << "The receiver of message '";
ME->getSelector().print(os);
os << "' is nil";
if (ResTy->isReferenceType()) {
os << ", which results in forming a null reference";
} else {
os << " and returns a value of type '";
msg.getResultType().print(os, C.getLangOpts());
os << "' that will be garbage";
}
auto report = llvm::make_unique<BugReport>(*BT_msg_ret, os.str(), N);
report->addRange(ME->getReceiverRange());
// FIXME: This won't track "self" in messages to super.
if (const Expr *receiver = ME->getInstanceReceiver()) {
bugreporter::trackNullOrUndefValue(N, receiver, *report);
}
C.emitReport(std::move(report));
}
static bool supportsNilWithFloatRet(const llvm::Triple &triple) {
return (triple.getVendor() == llvm::Triple::Apple &&
(triple.isiOS() || triple.isWatchOS() ||
!triple.isMacOSXVersionLT(10,5)));
}
void CallAndMessageChecker::HandleNilReceiver(CheckerContext &C,
ProgramStateRef state,
const ObjCMethodCall &Msg) const {
ASTContext &Ctx = C.getASTContext();
static CheckerProgramPointTag Tag(this, "NilReceiver");
// 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.getResultType();
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(RetTy);
C.addTransition(state->BindExpr(Msg.getOriginExpr(), LCtx, V), &Tag);
return;
}
// Other cases: check if sizeof(return type) > sizeof(void*)
if (CanRetTy != Ctx.VoidTy && C.getLocationContext()->getParentMap()
.isConsumedExpr(Msg.getOriginExpr())) {
// Compute: sizeof(void *) and sizeof(return type)
const uint64_t voidPtrSize = Ctx.getTypeSize(Ctx.VoidPtrTy);
const uint64_t returnTypeSize = Ctx.getTypeSize(CanRetTy);
if (CanRetTy.getTypePtr()->isReferenceType()||
(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.generateErrorNode(state, &Tag))
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(RetTy);
C.addTransition(state->BindExpr(Msg.getOriginExpr(), LCtx, V), &Tag);
return;
}
C.addTransition(state);
}
#define REGISTER_CHECKER(name) \
void ento::register##name(CheckerManager &mgr) { \
CallAndMessageChecker *Checker = \
mgr.registerChecker<CallAndMessageChecker>(); \
Checker->Filter.Check_##name = true; \
Checker->Filter.CheckName_##name = mgr.getCurrentCheckName(); \
}
REGISTER_CHECKER(CallAndMessageUnInitRefArg)
REGISTER_CHECKER(CallAndMessageChecker)