forked from OSchip/llvm-project
224 lines
7.5 KiB
C++
224 lines
7.5 KiB
C++
//===--- NonNullParamChecker.cpp - Undefined arguments checker -*- C++ -*--===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This defines NonNullParamChecker, which checks for arguments expected not to
|
|
// be null due to:
|
|
// - the corresponding parameters being declared to have nonnull attribute
|
|
// - the corresponding parameters being references; since the call would form
|
|
// a reference to a null pointer
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "ClangSACheckers.h"
|
|
#include "clang/AST/Attr.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"
|
|
|
|
using namespace clang;
|
|
using namespace ento;
|
|
|
|
namespace {
|
|
class NonNullParamChecker
|
|
: public Checker< check::PreCall, EventDispatcher<ImplicitNullDerefEvent> > {
|
|
mutable std::unique_ptr<BugType> BTAttrNonNull;
|
|
mutable std::unique_ptr<BugType> BTNullRefArg;
|
|
|
|
public:
|
|
|
|
void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
|
|
|
|
std::unique_ptr<BugReport>
|
|
genReportNullAttrNonNull(const ExplodedNode *ErrorN, const Expr *ArgE) const;
|
|
std::unique_ptr<BugReport>
|
|
genReportReferenceToNullPointer(const ExplodedNode *ErrorN,
|
|
const Expr *ArgE) const;
|
|
};
|
|
} // end anonymous namespace
|
|
|
|
void NonNullParamChecker::checkPreCall(const CallEvent &Call,
|
|
CheckerContext &C) const {
|
|
const Decl *FD = Call.getDecl();
|
|
if (!FD)
|
|
return;
|
|
|
|
// Merge all non-null attributes
|
|
unsigned NumArgs = Call.getNumArgs();
|
|
llvm::SmallBitVector AttrNonNull(NumArgs);
|
|
for (const auto *NonNull : FD->specific_attrs<NonNullAttr>()) {
|
|
if (!NonNull->args_size()) {
|
|
AttrNonNull.set(0, NumArgs);
|
|
break;
|
|
}
|
|
for (unsigned Val : NonNull->args()) {
|
|
if (Val >= NumArgs)
|
|
continue;
|
|
AttrNonNull.set(Val);
|
|
}
|
|
}
|
|
|
|
ProgramStateRef state = C.getState();
|
|
|
|
CallEvent::param_type_iterator TyI = Call.param_type_begin(),
|
|
TyE = Call.param_type_end();
|
|
|
|
for (unsigned idx = 0; idx < NumArgs; ++idx) {
|
|
|
|
// Check if the parameter is a reference. We want to report when reference
|
|
// to a null pointer is passed as a paramter.
|
|
bool haveRefTypeParam = false;
|
|
if (TyI != TyE) {
|
|
haveRefTypeParam = (*TyI)->isReferenceType();
|
|
TyI++;
|
|
}
|
|
|
|
bool haveAttrNonNull = AttrNonNull[idx];
|
|
if (!haveAttrNonNull) {
|
|
// Check if the parameter is also marked 'nonnull'.
|
|
ArrayRef<ParmVarDecl*> parms = Call.parameters();
|
|
if (idx < parms.size())
|
|
haveAttrNonNull = parms[idx]->hasAttr<NonNullAttr>();
|
|
}
|
|
|
|
if (!haveRefTypeParam && !haveAttrNonNull)
|
|
continue;
|
|
|
|
// If the value is unknown or undefined, we can't perform this check.
|
|
const Expr *ArgE = Call.getArgExpr(idx);
|
|
SVal V = Call.getArgSVal(idx);
|
|
Optional<DefinedSVal> DV = V.getAs<DefinedSVal>();
|
|
if (!DV)
|
|
continue;
|
|
|
|
// Process the case when the argument is not a location.
|
|
assert(!haveRefTypeParam || DV->getAs<Loc>());
|
|
|
|
if (haveAttrNonNull && !DV->getAs<Loc>()) {
|
|
// If the argument is a union type, we want to handle a potential
|
|
// transparent_union GCC extension.
|
|
if (!ArgE)
|
|
continue;
|
|
|
|
QualType T = ArgE->getType();
|
|
const RecordType *UT = T->getAsUnionType();
|
|
if (!UT || !UT->getDecl()->hasAttr<TransparentUnionAttr>())
|
|
continue;
|
|
|
|
if (Optional<nonloc::CompoundVal> CSV =
|
|
DV->getAs<nonloc::CompoundVal>()) {
|
|
nonloc::CompoundVal::iterator CSV_I = CSV->begin();
|
|
assert(CSV_I != CSV->end());
|
|
V = *CSV_I;
|
|
DV = V.getAs<DefinedSVal>();
|
|
assert(++CSV_I == CSV->end());
|
|
// FIXME: Handle (some_union){ some_other_union_val }, which turns into
|
|
// a LazyCompoundVal inside a CompoundVal.
|
|
if (!V.getAs<Loc>())
|
|
continue;
|
|
// Retrieve the corresponding expression.
|
|
if (const CompoundLiteralExpr *CE = dyn_cast<CompoundLiteralExpr>(ArgE))
|
|
if (const InitListExpr *IE =
|
|
dyn_cast<InitListExpr>(CE->getInitializer()))
|
|
ArgE = dyn_cast<Expr>(*(IE->begin()));
|
|
|
|
} else {
|
|
// FIXME: Handle LazyCompoundVals?
|
|
continue;
|
|
}
|
|
}
|
|
|
|
ConstraintManager &CM = C.getConstraintManager();
|
|
ProgramStateRef stateNotNull, stateNull;
|
|
std::tie(stateNotNull, stateNull) = CM.assumeDual(state, *DV);
|
|
|
|
if (stateNull) {
|
|
if (!stateNotNull) {
|
|
// Generate an error node. Check for a null node in case
|
|
// we cache out.
|
|
if (ExplodedNode *errorNode = C.generateErrorNode(stateNull)) {
|
|
|
|
std::unique_ptr<BugReport> R;
|
|
if (haveAttrNonNull)
|
|
R = genReportNullAttrNonNull(errorNode, ArgE);
|
|
else if (haveRefTypeParam)
|
|
R = genReportReferenceToNullPointer(errorNode, ArgE);
|
|
|
|
// Highlight the range of the argument that was null.
|
|
R->addRange(Call.getArgSourceRange(idx));
|
|
|
|
// Emit the bug report.
|
|
C.emitReport(std::move(R));
|
|
}
|
|
|
|
// Always return. Either we cached out or we just emitted an error.
|
|
return;
|
|
}
|
|
if (ExplodedNode *N = C.generateSink(stateNull, C.getPredecessor())) {
|
|
ImplicitNullDerefEvent event = {
|
|
V, false, N, &C.getBugReporter(),
|
|
/*IsDirectDereference=*/haveRefTypeParam};
|
|
dispatchEvent(event);
|
|
}
|
|
}
|
|
|
|
// If a pointer value passed the check we should assume that it is
|
|
// indeed not null from this point forward.
|
|
assert(stateNotNull);
|
|
state = stateNotNull;
|
|
}
|
|
|
|
// If we reach here all of the arguments passed the nonnull check.
|
|
// If 'state' has been updated generated a new node.
|
|
C.addTransition(state);
|
|
}
|
|
|
|
std::unique_ptr<BugReport>
|
|
NonNullParamChecker::genReportNullAttrNonNull(const ExplodedNode *ErrorNode,
|
|
const Expr *ArgE) const {
|
|
// Lazily allocate the BugType object if it hasn't already been
|
|
// created. Ownership is transferred to the BugReporter object once
|
|
// the BugReport is passed to 'EmitWarning'.
|
|
if (!BTAttrNonNull)
|
|
BTAttrNonNull.reset(new BugType(
|
|
this, "Argument with 'nonnull' attribute passed null", "API"));
|
|
|
|
auto R = llvm::make_unique<BugReport>(
|
|
*BTAttrNonNull,
|
|
"Null pointer passed as an argument to a 'nonnull' parameter", ErrorNode);
|
|
if (ArgE)
|
|
bugreporter::trackNullOrUndefValue(ErrorNode, ArgE, *R);
|
|
|
|
return R;
|
|
}
|
|
|
|
std::unique_ptr<BugReport> NonNullParamChecker::genReportReferenceToNullPointer(
|
|
const ExplodedNode *ErrorNode, const Expr *ArgE) const {
|
|
if (!BTNullRefArg)
|
|
BTNullRefArg.reset(new BuiltinBug(this, "Dereference of null pointer"));
|
|
|
|
auto R = llvm::make_unique<BugReport>(
|
|
*BTNullRefArg, "Forming reference to null pointer", ErrorNode);
|
|
if (ArgE) {
|
|
const Expr *ArgEDeref = bugreporter::getDerefExpr(ArgE);
|
|
if (!ArgEDeref)
|
|
ArgEDeref = ArgE;
|
|
bugreporter::trackNullOrUndefValue(ErrorNode,
|
|
ArgEDeref,
|
|
*R);
|
|
}
|
|
return R;
|
|
|
|
}
|
|
|
|
void ento::registerNonNullParamChecker(CheckerManager &mgr) {
|
|
mgr.registerChecker<NonNullParamChecker>();
|
|
}
|