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//=-- GRExprEngineInternalChecks.cpp - Builtin GRExprEngine Checks---*- C++ -*-=
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the BugType classes used by GRExprEngine to report
// bugs derived from builtin checks in the path-sensitive engine.
//
//===----------------------------------------------------------------------===//
#include "clang/Analysis/PathSensitive/BugReporter.h"
#include "clang/Analysis/PathSensitive/GRExprEngine.h"
#include "clang/Basic/SourceManager.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/raw_ostream.h"
using namespace clang;
//===----------------------------------------------------------------------===//
// Utility functions.
//===----------------------------------------------------------------------===//
template <typename ITERATOR> inline
ExplodedNode<GRState>* GetNode(ITERATOR I) {
return *I;
}
template <> inline
ExplodedNode<GRState>* GetNode(GRExprEngine::undef_arg_iterator I) {
return I->first;
}
//===----------------------------------------------------------------------===//
// Bug Descriptions.
//===----------------------------------------------------------------------===//
namespace {
class VISIBILITY_HIDDEN BuiltinBug : public BugTypeCacheLocation {
protected:
const char* name;
const char* desc;
public:
BuiltinBug(const char* n, const char* d = 0) : name(n), desc(d) {}
virtual const char* getName() const { return name; }
virtual const char* getDescription() const {
return desc ? desc : name;
}
virtual void EmitBuiltinWarnings(BugReporter& BR, GRExprEngine& Eng) = 0;
virtual void EmitWarnings(BugReporter& BR) {
EmitBuiltinWarnings(BR, cast<GRBugReporter>(BR).getEngine());
}
template <typename ITER>
void Emit(BugReporter& BR, ITER I, ITER E) {
for (; I != E; ++I) {
BugReport R(*this, GetNode(I));
BR.EmitWarning(R);
}
}
virtual const char* getCategory() const { return "Logic Errors"; }
};
class VISIBILITY_HIDDEN NullDeref : public BuiltinBug {
public:
NullDeref() : BuiltinBug("null dereference",
"Dereference of null pointer.") {}
virtual void EmitBuiltinWarnings(BugReporter& BR, GRExprEngine& Eng) {
Emit(BR, Eng.null_derefs_begin(), Eng.null_derefs_end());
}
};
class VISIBILITY_HIDDEN UndefinedDeref : public BuiltinBug {
public:
UndefinedDeref() : BuiltinBug("uninitialized pointer dereference",
"Dereference of undefined value.") {}
virtual void EmitBuiltinWarnings(BugReporter& BR, GRExprEngine& Eng) {
Emit(BR, Eng.undef_derefs_begin(), Eng.undef_derefs_end());
}
};
class VISIBILITY_HIDDEN DivZero : public BuiltinBug {
public:
DivZero() : BuiltinBug("divide-by-zero",
"Division by zero/undefined value.") {}
virtual void EmitBuiltinWarnings(BugReporter& BR, GRExprEngine& Eng) {
Emit(BR, Eng.explicit_bad_divides_begin(), Eng.explicit_bad_divides_end());
}
};
class VISIBILITY_HIDDEN UndefResult : public BuiltinBug {
public:
UndefResult() : BuiltinBug("undefined result",
"Result of operation is undefined.") {}
virtual void EmitBuiltinWarnings(BugReporter& BR, GRExprEngine& Eng) {
Emit(BR, Eng.undef_results_begin(), Eng.undef_results_end());
}
};
class VISIBILITY_HIDDEN BadCall : public BuiltinBug {
public:
BadCall()
: BuiltinBug("invalid function call",
"Called function is a NULL or undefined function pointer value.") {}
virtual void EmitBuiltinWarnings(BugReporter& BR, GRExprEngine& Eng) {
Emit(BR, Eng.bad_calls_begin(), Eng.bad_calls_end());
}
};
class VISIBILITY_HIDDEN BadArg : public BuiltinBug {
public:
BadArg() : BuiltinBug("uninitialized argument",
"Pass-by-value argument in function is undefined.") {}
BadArg(const char* d) : BuiltinBug("uninitialized argument", d) {}
virtual void EmitBuiltinWarnings(BugReporter& BR, GRExprEngine& Eng) {
for (GRExprEngine::UndefArgsTy::iterator I = Eng.undef_arg_begin(),
E = Eng.undef_arg_end(); I!=E; ++I) {
// Generate a report for this bug.
RangedBugReport report(*this, I->first);
report.addRange(I->second->getSourceRange());
// Emit the warning.
BR.EmitWarning(report);
}
}
};
class VISIBILITY_HIDDEN BadMsgExprArg : public BadArg {
public:
BadMsgExprArg()
: BadArg("Pass-by-value argument in message expression is undefined.") {}
virtual void EmitBuiltinWarnings(BugReporter& BR, GRExprEngine& Eng) {
for (GRExprEngine::UndefArgsTy::iterator I=Eng.msg_expr_undef_arg_begin(),
E = Eng.msg_expr_undef_arg_end(); I!=E; ++I) {
// Generate a report for this bug.
RangedBugReport report(*this, I->first);
report.addRange(I->second->getSourceRange());
// Emit the warning.
BR.EmitWarning(report);
}
}
};
class VISIBILITY_HIDDEN BadReceiver : public BuiltinBug {
public:
BadReceiver()
: BuiltinBug("uninitialized receiver",
"Receiver in message expression is an uninitialized value.") {}
virtual void EmitBuiltinWarnings(BugReporter& BR, GRExprEngine& Eng) {
for (GRExprEngine::ErrorNodes::iterator I=Eng.undef_receivers_begin(),
End = Eng.undef_receivers_end(); I!=End; ++I) {
// Generate a report for this bug.
RangedBugReport report(*this, *I);
ExplodedNode<GRState>* N = *I;
Stmt *S = cast<PostStmt>(N->getLocation()).getStmt();
Expr* E = cast<ObjCMessageExpr>(S)->getReceiver();
assert (E && "Receiver cannot be NULL");
report.addRange(E->getSourceRange());
// Emit the warning.
BR.EmitWarning(report);
}
}
};
class VISIBILITY_HIDDEN RetStack : public BuiltinBug {
public:
RetStack() : BuiltinBug("return of stack address") {}
virtual void EmitBuiltinWarnings(BugReporter& BR, GRExprEngine& Eng) {
for (GRExprEngine::ret_stackaddr_iterator I=Eng.ret_stackaddr_begin(),
End = Eng.ret_stackaddr_end(); I!=End; ++I) {
ExplodedNode<GRState>* N = *I;
Stmt *S = cast<PostStmt>(N->getLocation()).getStmt();
Expr* E = cast<ReturnStmt>(S)->getRetValue();
assert (E && "Return expression cannot be NULL");
// Get the value associated with E.
loc::MemRegionVal V =
cast<loc::MemRegionVal>(Eng.getStateManager().GetSVal(N->getState(),
E));
// Generate a report for this bug.
std::string buf;
llvm::raw_string_ostream os(buf);
SourceRange R;
// Check if the region is a compound literal.
if (const CompoundLiteralRegion* CR =
dyn_cast<CompoundLiteralRegion>(V.getRegion())) {
const CompoundLiteralExpr* CL = CR->getLiteralExpr();
os << "Address of stack memory associated with a compound literal "
"declared on line "
<< BR.getSourceManager().getLogicalLineNumber(CL->getLocStart())
<< " returned.";
R = CL->getSourceRange();
}
else if (const AllocaRegion* AR = dyn_cast<AllocaRegion>(V.getRegion())) {
const Expr* ARE = AR->getExpr();
SourceLocation L = ARE->getLocStart();
R = ARE->getSourceRange();
os << "Address of stack memory allocated by call to alloca() on line "
<< BR.getSourceManager().getLogicalLineNumber(L)
<< " returned.";
}
else {
os << "Address of stack memory associated with local variable '"
<< V.getRegion()->getString() << "' returned.";
}
RangedBugReport report(*this, N, os.str().c_str());
report.addRange(E->getSourceRange());
if (R.isValid()) report.addRange(R);
// Emit the warning.
BR.EmitWarning(report);
}
}
};
class VISIBILITY_HIDDEN RetUndef : public BuiltinBug {
public:
RetUndef() : BuiltinBug("uninitialized return value",
"Uninitialized or undefined return value returned to caller.") {}
virtual void EmitBuiltinWarnings(BugReporter& BR, GRExprEngine& Eng) {
Emit(BR, Eng.ret_undef_begin(), Eng.ret_undef_end());
}
};
class VISIBILITY_HIDDEN UndefBranch : public BuiltinBug {
struct VISIBILITY_HIDDEN FindUndefExpr {
GRStateManager& VM;
const GRState* St;
FindUndefExpr(GRStateManager& V, const GRState* S) : VM(V), St(S) {}
Expr* FindExpr(Expr* Ex) {
if (!MatchesCriteria(Ex))
return 0;
for (Stmt::child_iterator I=Ex->child_begin(), E=Ex->child_end();I!=E;++I)
if (Expr* ExI = dyn_cast_or_null<Expr>(*I)) {
Expr* E2 = FindExpr(ExI);
if (E2) return E2;
}
return Ex;
}
bool MatchesCriteria(Expr* Ex) { return VM.GetSVal(St, Ex).isUndef(); }
};
public:
UndefBranch()
: BuiltinBug("uninitialized value",
"Branch condition evaluates to an uninitialized value.") {}
virtual void EmitBuiltinWarnings(BugReporter& BR, GRExprEngine& Eng) {
for (GRExprEngine::undef_branch_iterator I=Eng.undef_branches_begin(),
E=Eng.undef_branches_end(); I!=E; ++I) {
// What's going on here: we want to highlight the subexpression of the
// condition that is the most likely source of the "uninitialized
// branch condition." We do a recursive walk of the condition's
// subexpressions and roughly look for the most nested subexpression
// that binds to Undefined. We then highlight that expression's range.
BlockEdge B = cast<BlockEdge>((*I)->getLocation());
Expr* Ex = cast<Expr>(B.getSrc()->getTerminatorCondition());
assert (Ex && "Block must have a terminator.");
// Get the predecessor node and check if is a PostStmt with the Stmt
// being the terminator condition. We want to inspect the state
// of that node instead because it will contain main information about
// the subexpressions.
assert (!(*I)->pred_empty());
// Note: any predecessor will do. They should have identical state,
// since all the BlockEdge did was act as an error sink since the value
// had to already be undefined.
ExplodedNode<GRState> *N = *(*I)->pred_begin();
ProgramPoint P = N->getLocation();
const GRState* St = (*I)->getState();
if (PostStmt* PS = dyn_cast<PostStmt>(&P))
if (PS->getStmt() == Ex)
St = N->getState();
FindUndefExpr FindIt(Eng.getStateManager(), St);
Ex = FindIt.FindExpr(Ex);
RangedBugReport R(*this, *I);
R.addRange(Ex->getSourceRange());
BR.EmitWarning(R);
}
}
};
class VISIBILITY_HIDDEN OutOfBoundMemoryAccess : public BuiltinBug {
public:
OutOfBoundMemoryAccess() : BuiltinBug("out-of-bound memory access",
"Load or store into an out-of-bound memory position.") {}
virtual void EmitBuiltinWarnings(BugReporter& BR, GRExprEngine& Eng) {
Emit(BR, Eng.explicit_oob_memacc_begin(), Eng.explicit_oob_memacc_end());
}
};
class VISIBILITY_HIDDEN BadSizeVLA : public BuiltinBug {
public:
BadSizeVLA() : BuiltinBug("Zero-sized VLA",
"VLAs with zero-size are undefined.") {}
virtual void EmitBuiltinWarnings(BugReporter& BR, GRExprEngine& Eng) {
for (GRExprEngine::ErrorNodes::iterator
I = Eng.ExplicitBadSizedVLA.begin(),
E = Eng.ExplicitBadSizedVLA.end(); I!=E; ++I) {
// Determine whether this was a 'zero-sized' VLA or a VLA with an
// undefined size.
GRExprEngine::NodeTy* N = *I;
PostStmt PS = cast<PostStmt>(N->getLocation());
DeclStmt *DS = cast<DeclStmt>(PS.getStmt());
VarDecl* VD = cast<VarDecl>(*DS->decl_begin());
QualType T = Eng.getContext().getCanonicalType(VD->getType());
VariableArrayType* VT = cast<VariableArrayType>(T);
Expr* SizeExpr = VT->getSizeExpr();
std::string buf;
llvm::raw_string_ostream os(buf);
os << "The expression used to specify the number of elements in the VLA '"
<< VD->getNameAsString() << "' evaluates to ";
SVal X = Eng.getStateManager().GetSVal(N->getState(), SizeExpr);
if (X.isUndef()) {
name = "Undefined size for VLA";
os << "an undefined or garbage value.";
}
else {
name = "Zero-sized VLA";
os << " to 0. VLAs with no elements have undefined behavior.";
}
desc = os.str().c_str();
RangedBugReport report(*this, N);
report.addRange(SizeExpr->getSourceRange());
// Emit the warning.
BR.EmitWarning(report);
}
}
};
//===----------------------------------------------------------------------===//
// __attribute__(nonnull) checking
class VISIBILITY_HIDDEN CheckAttrNonNull : public GRSimpleAPICheck {
SimpleBugType BT;
std::list<RangedBugReport> Reports;
public:
CheckAttrNonNull() :
BT("'nonnull' argument passed null", "API",
"Null pointer passed as an argument to a 'nonnull' parameter") {}
virtual bool Audit(ExplodedNode<GRState>* N, GRStateManager& VMgr) {
CallExpr* CE = cast<CallExpr>(cast<PostStmt>(N->getLocation()).getStmt());
const GRState* state = N->getState();
SVal X = VMgr.GetSVal(state, CE->getCallee());
if (!isa<loc::FuncVal>(X))
return false;
FunctionDecl* FD = dyn_cast<FunctionDecl>(cast<loc::FuncVal>(X).getDecl());
const NonNullAttr* Att = FD->getAttr<NonNullAttr>();
if (!Att)
return false;
// Iterate through the arguments of CE and check them for null.
unsigned idx = 0;
bool hasError = false;
for (CallExpr::arg_iterator I=CE->arg_begin(), E=CE->arg_end(); I!=E;
++I, ++idx) {
if (!VMgr.isEqual(state, *I, 0) || !Att->isNonNull(idx))
continue;
RangedBugReport R(BT, N);
R.addRange((*I)->getSourceRange());
Reports.push_back(R);
hasError = true;
}
return hasError;
}
virtual void EmitWarnings(BugReporter& BR) {
for (std::list<RangedBugReport>::iterator I=Reports.begin(),
E=Reports.end(); I!=E; ++I)
BR.EmitWarning(*I);
}
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// Check registration.
void GRExprEngine::RegisterInternalChecks() {
Register(new NullDeref());
Register(new UndefinedDeref());
Register(new UndefBranch());
Register(new DivZero());
Register(new UndefResult());
Register(new BadCall());
Register(new RetStack());
Register(new RetUndef());
Register(new BadArg());
Register(new BadMsgExprArg());
Register(new BadReceiver());
Register(new OutOfBoundMemoryAccess());
Register(new BadSizeVLA());
AddCheck(new CheckAttrNonNull(), Stmt::CallExprClass);
}