[analyzer] Add support for more invalidating functions in InnerPointerChecker.

According to the standard, pointers referring to the elements of a
`basic_string` may be invalidated if they are used as an argument to
any standard library function taking a reference to non-const
`basic_string` as an argument. This patch makes InnerPointerChecker warn
for these cases.

Differential Revision: https://reviews.llvm.org/D49656

llvm-svn: 338259
This commit is contained in:
Reka Kovacs 2018-07-30 15:43:45 +00:00
parent 9b33309c87
commit c74cfc4215
3 changed files with 217 additions and 74 deletions

View File

@ -91,37 +91,53 @@ public:
ReserveFn("reserve"), ResizeFn("resize"),
ShrinkToFitFn("shrink_to_fit"), SwapFn("swap") {}
/// Check whether the function called on the container object is a
/// member function that potentially invalidates pointers referring
/// to the objects's internal buffer.
bool mayInvalidateBuffer(const CallEvent &Call) const;
/// Check if the object of this member function call is a `basic_string`.
bool isCalledOnStringObject(const CXXInstanceCall *ICall) const;
/// Record the connection between the symbol returned by c_str() and the
/// corresponding string object region in the ProgramState. Mark the symbol
/// released if the string object is destroyed.
/// Check whether the called member function potentially invalidates
/// pointers referring to the container object's inner buffer.
bool isInvalidatingMemberFunction(const CallEvent &Call) const;
/// Mark pointer symbols associated with the given memory region released
/// in the program state.
void markPtrSymbolsReleased(const CallEvent &Call, ProgramStateRef State,
const MemRegion *ObjRegion,
CheckerContext &C) const;
/// Standard library functions that take a non-const `basic_string` argument by
/// reference may invalidate its inner pointers. Check for these cases and
/// mark the pointers released.
void checkFunctionArguments(const CallEvent &Call, ProgramStateRef State,
CheckerContext &C) const;
/// Record the connection between raw pointers referring to a container
/// object's inner buffer and the object's memory region in the program state.
/// Mark potentially invalidated pointers released.
void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
/// Clean up the ProgramState map.
/// Clean up the program state map.
void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
};
} // end anonymous namespace
// [string.require]
//
// "References, pointers, and iterators referring to the elements of a
// basic_string sequence may be invalidated by the following uses of that
// basic_string object:
//
// -- TODO: As an argument to any standard library function taking a reference
// to non-const basic_string as an argument. For example, as an argument to
// non-member functions swap(), operator>>(), and getline(), or as an argument
// to basic_string::swap().
//
// -- Calling non-const member functions, except operator[], at, front, back,
// begin, rbegin, end, and rend."
//
bool InnerPointerChecker::mayInvalidateBuffer(const CallEvent &Call) const {
bool InnerPointerChecker::isCalledOnStringObject(
const CXXInstanceCall *ICall) const {
const auto *ObjRegion =
dyn_cast_or_null<TypedValueRegion>(ICall->getCXXThisVal().getAsRegion());
if (!ObjRegion)
return false;
QualType ObjTy = ObjRegion->getValueType();
if (ObjTy.isNull() ||
ObjTy->getAsCXXRecordDecl()->getName() != "basic_string")
return false;
return true;
}
bool InnerPointerChecker::isInvalidatingMemberFunction(
const CallEvent &Call) const {
if (const auto *MemOpCall = dyn_cast<CXXMemberOperatorCall>(&Call)) {
OverloadedOperatorKind Opc = MemOpCall->getOriginExpr()->getOperator();
if (Opc == OO_Equal || Opc == OO_PlusEqual)
@ -137,53 +153,104 @@ bool InnerPointerChecker::mayInvalidateBuffer(const CallEvent &Call) const {
Call.isCalled(SwapFn));
}
void InnerPointerChecker::markPtrSymbolsReleased(const CallEvent &Call,
ProgramStateRef State,
const MemRegion *MR,
CheckerContext &C) const {
if (const PtrSet *PS = State->get<RawPtrMap>(MR)) {
const Expr *Origin = Call.getOriginExpr();
for (const auto Symbol : *PS) {
// NOTE: `Origin` may be null, and will be stored so in the symbol's
// `RefState` in MallocChecker's `RegionState` program state map.
State = allocation_state::markReleased(State, Symbol, Origin);
}
State = State->remove<RawPtrMap>(MR);
C.addTransition(State);
return;
}
}
void InnerPointerChecker::checkFunctionArguments(const CallEvent &Call,
ProgramStateRef State,
CheckerContext &C) const {
if (const auto *FC = dyn_cast<AnyFunctionCall>(&Call)) {
const FunctionDecl *FD = FC->getDecl();
if (!FD || !FD->isInStdNamespace())
return;
for (unsigned I = 0, E = FD->getNumParams(); I != E; ++I) {
QualType ParamTy = FD->getParamDecl(I)->getType();
if (!ParamTy->isReferenceType() ||
ParamTy->getPointeeType().isConstQualified())
continue;
// In case of member operator calls, `this` is counted as an
// argument but not as a parameter.
bool isaMemberOpCall = isa<CXXMemberOperatorCall>(FC);
unsigned ArgI = isaMemberOpCall ? I+1 : I;
SVal Arg = FC->getArgSVal(ArgI);
const auto *ArgRegion =
dyn_cast_or_null<TypedValueRegion>(Arg.getAsRegion());
if (!ArgRegion)
continue;
markPtrSymbolsReleased(Call, State, ArgRegion, C);
}
}
}
// [string.require]
//
// "References, pointers, and iterators referring to the elements of a
// basic_string sequence may be invalidated by the following uses of that
// basic_string object:
//
// -- As an argument to any standard library function taking a reference
// to non-const basic_string as an argument. For example, as an argument to
// non-member functions swap(), operator>>(), and getline(), or as an argument
// to basic_string::swap().
//
// -- Calling non-const member functions, except operator[], at, front, back,
// begin, rbegin, end, and rend."
void InnerPointerChecker::checkPostCall(const CallEvent &Call,
CheckerContext &C) const {
const auto *ICall = dyn_cast<CXXInstanceCall>(&Call);
if (!ICall)
return;
SVal Obj = ICall->getCXXThisVal();
const auto *ObjRegion = dyn_cast_or_null<TypedValueRegion>(Obj.getAsRegion());
if (!ObjRegion)
return;
auto *TypeDecl = ObjRegion->getValueType()->getAsCXXRecordDecl();
if (TypeDecl->getName() != "basic_string")
return;
ProgramStateRef State = C.getState();
if (Call.isCalled(CStrFn) || Call.isCalled(DataFn)) {
SVal RawPtr = Call.getReturnValue();
if (SymbolRef Sym = RawPtr.getAsSymbol(/*IncludeBaseRegions=*/true)) {
// Start tracking this raw pointer by adding it to the set of symbols
// associated with this container object in the program state map.
PtrSet::Factory &F = State->getStateManager().get_context<PtrSet>();
const PtrSet *SetPtr = State->get<RawPtrMap>(ObjRegion);
PtrSet Set = SetPtr ? *SetPtr : F.getEmptySet();
assert(C.wasInlined || !Set.contains(Sym));
Set = F.add(Set, Sym);
State = State->set<RawPtrMap>(ObjRegion, Set);
C.addTransition(State);
if (const auto *ICall = dyn_cast<CXXInstanceCall>(&Call)) {
if (isCalledOnStringObject(ICall)) {
const auto *ObjRegion = dyn_cast_or_null<TypedValueRegion>(
ICall->getCXXThisVal().getAsRegion());
if (Call.isCalled(CStrFn) || Call.isCalled(DataFn)) {
SVal RawPtr = Call.getReturnValue();
if (SymbolRef Sym = RawPtr.getAsSymbol(/*IncludeBaseRegions=*/true)) {
// Start tracking this raw pointer by adding it to the set of symbols
// associated with this container object in the program state map.
PtrSet::Factory &F = State->getStateManager().get_context<PtrSet>();
const PtrSet *SetPtr = State->get<RawPtrMap>(ObjRegion);
PtrSet Set = SetPtr ? *SetPtr : F.getEmptySet();
assert(C.wasInlined || !Set.contains(Sym));
Set = F.add(Set, Sym);
State = State->set<RawPtrMap>(ObjRegion, Set);
C.addTransition(State);
}
return;
}
// Check [string.require] / second point.
if (isInvalidatingMemberFunction(Call)) {
markPtrSymbolsReleased(Call, State, ObjRegion, C);
return;
}
}
return;
}
if (mayInvalidateBuffer(Call)) {
if (const PtrSet *PS = State->get<RawPtrMap>(ObjRegion)) {
// Mark all pointer symbols associated with the deleted object released.
const Expr *Origin = Call.getOriginExpr();
for (const auto Symbol : *PS) {
// NOTE: `Origin` may be null, and will be stored so in the symbol's
// `RefState` in MallocChecker's `RegionState` program state map.
State = allocation_state::markReleased(State, Symbol, Origin);
}
State = State->remove<RawPtrMap>(ObjRegion);
C.addTransition(State);
return;
}
}
// Check [string.require] / first point.
checkFunctionArguments(Call, State, C);
}
void InnerPointerChecker::checkDeadSymbols(SymbolReaper &SymReaper,
@ -216,7 +283,6 @@ InnerPointerChecker::InnerPointerBRVisitor::VisitNode(const ExplodedNode *N,
const ExplodedNode *PrevN,
BugReporterContext &BRC,
BugReport &BR) {
if (!isSymbolTracked(N->getState(), PtrToBuf) ||
isSymbolTracked(PrevN->getState(), PtrToBuf))
return nullptr;

View File

@ -2930,6 +2930,11 @@ std::shared_ptr<PathDiagnosticPiece> MallocChecker::MallocBugVisitor::VisitNode(
OS << MemCallE->getMethodDecl()->getNameAsString();
} else if (const auto *OpCallE = dyn_cast<CXXOperatorCallExpr>(S)) {
OS << OpCallE->getDirectCallee()->getNameAsString();
} else if (const auto *CallE = dyn_cast<CallExpr>(S)) {
auto &CEMgr = BRC.getStateManager().getCallEventManager();
CallEventRef<> Call = CEMgr.getSimpleCall(CallE, state, CurrentLC);
const auto *D = dyn_cast_or_null<NamedDecl>(Call->getDecl());
OS << (D ? D->getNameAsString() : "unknown");
}
OS << "'";
}

View File

@ -38,6 +38,18 @@ typedef basic_string<wchar_t> wstring;
typedef basic_string<char16_t> u16string;
typedef basic_string<char32_t> u32string;
template <typename T>
void func_ref(T &a);
template <typename T>
void func_const_ref(const T &a);
template <typename T>
void func_value(T a);
string my_string = "default";
void default_arg(int a = 42, string &b = my_string);
} // end namespace std
void consume(const char *) {}
@ -45,6 +57,10 @@ void consume(const wchar_t *) {}
void consume(const char16_t *) {}
void consume(const char32_t *) {}
//=--------------------------------------=//
// `std::string` member functions //
//=--------------------------------------=//
void deref_after_scope_char(bool cond) {
const char *c, *d;
{
@ -151,6 +167,19 @@ void multiple_symbols(bool cond) {
} // expected-note@-1 {{Use of memory after it is freed}}
}
void deref_after_scope_ok(bool cond) {
const char *c, *d;
std::string s;
{
c = s.c_str();
d = s.data();
}
if (cond)
consume(c); // no-warning
else
consume(d); // no-warning
}
void deref_after_equals() {
const char *c;
std::string s = "hello";
@ -277,15 +306,58 @@ void deref_after_swap() {
// expected-note@-1 {{Use of memory after it is freed}}
}
void deref_after_scope_ok(bool cond) {
const char *c, *d;
//=---------------------------=//
// Other STL functions //
//=---------------------------=//
void STL_func_ref() {
const char *c;
std::string s;
{
c = s.c_str();
d = s.data();
}
if (cond)
consume(c); // no-warning
else
consume(d); // no-warning
c = s.c_str(); // expected-note {{Dangling inner pointer obtained here}}
std::func_ref(s); // expected-note {{Inner pointer invalidated by call to 'func_ref'}}
consume(c); // expected-warning {{Use of memory after it is freed}}
// expected-note@-1 {{Use of memory after it is freed}}
}
void STL_func_const_ref() {
const char *c;
std::string s;
c = s.c_str();
std::func_const_ref(s);
consume(c); // no-warning
}
void STL_func_value() {
const char *c;
std::string s;
c = s.c_str();
std::func_value(s);
consume(c); // no-warning
}
void func_ptr_known() {
const char *c;
std::string s;
void (*func_ptr)(std::string &) = std::func_ref<std::string>;
c = s.c_str(); // expected-note {{Dangling inner pointer obtained here}}
func_ptr(s); // expected-note {{Inner pointer invalidated by call to 'func_ref'}}
consume(c); // expected-warning {{Use of memory after it is freed}}
// expected-note@-1 {{Use of memory after it is freed}}
}
void func_ptr_unknown(void (*func_ptr)(std::string &)) {
const char *c;
std::string s;
c = s.c_str();
func_ptr(s);
consume(c); // no-warning
}
void func_default_arg() {
const char *c;
std::string s;
c = s.c_str(); // expected-note {{Dangling inner pointer obtained here}}
default_arg(3, s); // expected-note {{Inner pointer invalidated by call to 'default_arg'}}
consume(c); // expected-warning {{Use of memory after it is freed}}
// expected-note@-1 {{Use of memory after it is freed}}
}