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//===--- 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 "clang/Analysis/PathSensitive/CheckerVisitor.h"
#include "clang/Analysis/PathSensitive/BugReporter.h"
#include "clang/AST/ParentMap.h"
#include "GRExprEngineInternalChecks.h"
using namespace clang;
namespace {
class VISIBILITY_HIDDEN CallAndMessageChecker
: public CheckerVisitor<CallAndMessageChecker> {
BugType *BT_call_null;
BugType *BT_call_undef;
BugType *BT_call_arg;
BugType *BT_msg_undef;
BugType *BT_msg_arg;
BugType *BT_struct_ret;
BugType *BT_void_ptr;
public:
CallAndMessageChecker() :
BT_call_null(0), BT_call_undef(0), BT_call_arg(0),
BT_msg_undef(0), BT_msg_arg(0), BT_struct_ret(0), BT_void_ptr(0) {}
static void *getTag() {
static int x = 0;
return &x;
}
void PreVisitCallExpr(CheckerContext &C, const CallExpr *CE);
void PreVisitObjCMessageExpr(CheckerContext &C, const ObjCMessageExpr *ME);
private:
void EmitBadCall(BugType *BT, CheckerContext &C, const CallExpr *CE);
};
} // end anonymous namespace
void clang::RegisterCallAndMessageChecker(GRExprEngine &Eng) {
Eng.registerCheck(new CallAndMessageChecker());
}
void CallAndMessageChecker::EmitBadCall(BugType *BT, CheckerContext &C,
const CallExpr *CE) {
ExplodedNode *N = C.GenerateSink();
if (!N)
return;
EnhancedBugReport *R = new EnhancedBugReport(*BT, BT->getName(), N);
R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue,
bugreporter::GetCalleeExpr(N));
C.EmitReport(R);
}
void CallAndMessageChecker::PreVisitCallExpr(CheckerContext &C,
const CallExpr *CE){
const Expr *Callee = CE->getCallee()->IgnoreParens();
SVal L = C.getState()->getSVal(Callee);
if (L.isUndef()) {
if (!BT_call_undef)
BT_call_undef =
new BuiltinBug("Called function pointer is an undefined pointer value");
EmitBadCall(BT_call_undef, C, CE);
return;
}
if (isa<loc::ConcreteInt>(L)) {
if (!BT_call_null)
BT_call_null =
new BuiltinBug("Called function pointer is null (null dereference)");
EmitBadCall(BT_call_null, C, CE);
}
for (CallExpr::const_arg_iterator I = CE->arg_begin(), E = CE->arg_end();
I != E; ++I) {
if (C.getState()->getSVal(*I).isUndef()) {
if (ExplodedNode *N = C.GenerateSink()) {
if (!BT_call_arg)
BT_call_arg = new BuiltinBug("Pass-by-value argument in function call"
" is undefined");
// Generate a report for this bug.
EnhancedBugReport *R = new EnhancedBugReport(*BT_call_arg,
BT_call_arg->getName(), N);
R->addRange((*I)->getSourceRange());
R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, *I);
C.EmitReport(R);
return;
}
}
}
}
void CallAndMessageChecker::PreVisitObjCMessageExpr(CheckerContext &C,
const ObjCMessageExpr *ME) {
const GRState *state = C.getState();
if (const Expr *receiver = ME->getReceiver())
if (state->getSVal(receiver).isUndef()) {
if (ExplodedNode *N = C.GenerateSink()) {
if (!BT_msg_undef)
BT_msg_undef =
new BuiltinBug("Receiver in message expression is a garbage value");
EnhancedBugReport *R =
new EnhancedBugReport(*BT_msg_undef, BT_msg_undef->getName(), N);
R->addRange(receiver->getSourceRange());
R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue,
receiver);
C.EmitReport(R);
}
return;
}
// Check for any arguments that are uninitialized/undefined.
for (ObjCMessageExpr::const_arg_iterator I = ME->arg_begin(),
E = ME->arg_end(); I != E; ++I) {
if (state->getSVal(*I).isUndef()) {
if (ExplodedNode *N = C.GenerateSink()) {
if (!BT_msg_arg)
BT_msg_arg =
new BuiltinBug("Pass-by-value argument in message expression"
" is undefined");
// Generate a report for this bug.
EnhancedBugReport *R = new EnhancedBugReport(*BT_msg_arg,
BT_msg_arg->getName(), N);
R->addRange((*I)->getSourceRange());
R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, *I);
C.EmitReport(R);
return;
}
}
}
// Check if the receiver was nil and then return value a struct.
if (const Expr *Receiver = ME->getReceiver()) {
SVal L_untested = state->getSVal(Receiver);
// Assume that the receiver is not NULL.
DefinedOrUnknownSVal L = cast<DefinedOrUnknownSVal>(L_untested);
const GRState *StNotNull = state->Assume(L, true);
// Assume that the receiver is NULL.
const GRState *StNull = state->Assume(L, false);
if (StNull) {
QualType RetTy = ME->getType();
if (RetTy->isRecordType()) {
if (C.getPredecessor()->getParentMap().isConsumedExpr(ME)) {
// The [0 ...] expressions will return garbage. Flag either an
// explicit or implicit error. Because of the structure of this
// function we currently do not bifurfacte the state graph at
// this point.
// FIXME: We should bifurcate and fill the returned struct with
// garbage.
if (ExplodedNode* N = C.GenerateSink(StNull)) {
if (!StNotNull) {
if (!BT_struct_ret) {
std::string sbuf;
llvm::raw_string_ostream os(sbuf);
os << "The receiver in the message expression is 'nil' and "
"results in the returned value (of type '"
<< ME->getType().getAsString()
<< "') to be garbage or otherwise undefined";
BT_struct_ret = new BuiltinBug(os.str().c_str());
}
EnhancedBugReport *R = new EnhancedBugReport(*BT_struct_ret,
BT_struct_ret->getName(), N);
R->addRange(Receiver->getSourceRange());
R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue,
Receiver);
C.EmitReport(R);
return;
}
else
// Do not report implicit bug.
return;
}
}
} else {
ASTContext &Ctx = C.getASTContext();
if (RetTy != Ctx.VoidTy) {
if (C.getPredecessor()->getParentMap().isConsumedExpr(ME)) {
// sizeof(void *)
const uint64_t voidPtrSize = Ctx.getTypeSize(Ctx.VoidPtrTy);
// sizeof(return type)
const uint64_t returnTypeSize = Ctx.getTypeSize(ME->getType());
if (voidPtrSize < returnTypeSize) {
if (ExplodedNode* N = C.GenerateSink(StNull)) {
if (!StNotNull) {
if (!BT_struct_ret) {
std::string sbuf;
llvm::raw_string_ostream os(sbuf);
os << "The receiver in the message expression is 'nil' and "
"results in the returned value (of type '"
<< ME->getType().getAsString()
<< "' and of size "
<< returnTypeSize / 8
<< " bytes) to be garbage or otherwise undefined";
BT_void_ptr = new BuiltinBug(os.str().c_str());
}
EnhancedBugReport *R = new EnhancedBugReport(*BT_void_ptr,
BT_void_ptr->getName(), N);
R->addRange(Receiver->getSourceRange());
R->addVisitorCreator(
bugreporter::registerTrackNullOrUndefValue, Receiver);
C.EmitReport(R);
return;
} else
// Do not report implicit bug.
return;
}
}
else if (!StNotNull) {
// 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.getValueManager().makeZeroVal(ME->getType());
C.GenerateNode(StNull->BindExpr(ME, V));
return;
}
}
}
}
}
// Do not propagate null state.
if (StNotNull)
C.GenerateNode(StNotNull);
}
}
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