Re: [PATCH 2/7] msvcrt: Clean up registered C++ object in handler.

[Piotr Caban]

On 05/24/17 02:55, Daniel Lehman wrote:
> +static DWORD cxx_catch_cleanup(EXCEPTION_RECORD *rec, EXCEPTION_REGISTRATION_RECORD *frame,
> +                               CONTEXT *context, EXCEPTION_REGISTRATION_RECORD **pdispatcher)
> +{
> +    if (rec->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND))
> +    {
> +        thread_data_t *data = msvcrt_get_thread_data();
> +        frame_info *cur;
> +
> +        if (cxx_is_consolidate(rec))
> Is this condition really needed? Shouldn't we clean the object no matter 
> what's the reason of unwind?
> +        {
> +            rec = (void*)rec->ExceptionInformation[4];
> +
> +            for (cur = data->frame_info_head; cur; cur = cur->next)
> +            {
> +                if ((ULONG64)cur <= (ULONG64)frame)
> This condition is not working. It's making assumption about order of 
> catch_frame and frame_info variables on stack while they are declared 
> this way:
> +    EXCEPTION_REGISTRATION_RECORD catch_frame;
>       cxx_frame_info frame_info;
> Shouldn't the cxx_catch_cleanup just unregister the object that was 
> registered in call_catch_block?

Thanks,
Piotr

[PATCH 2/7] msvcrt: Clean up registered C++ object in handler.

[Piotr Caban]

On 05/29/17 21:56, Piotr Caban wrote:
> On 05/24/17 02:55, Daniel Lehman wrote:
> > +static DWORD cxx_catch_cleanup(EXCEPTION_RECORD *rec, 
> > EXCEPTION_REGISTRATION_RECORD *frame,
> > +                               CONTEXT *context, 
> > EXCEPTION_REGISTRATION_RECORD **pdispatcher)
> > +{
> > +    if (rec->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND))
> > +    {
> > +        thread_data_t *data = msvcrt_get_thread_data();
> > +        frame_info *cur;
> > +
> > +        if (cxx_is_consolidate(rec))
> > Is this condition really needed? Shouldn't we clean the object no matter 
> > what's the reason of unwind?
> > +        {
> > +            rec = (void*)rec->ExceptionInformation[4];
> > +
> > +            for (cur = data->frame_info_head; cur; cur = cur->next)
> > +            {
> > +                if ((ULONG64)cur <= (ULONG64)frame)
> > This condition is not working. It's making assumption about order of 
> > catch_frame and frame_info variables on stack while they are declared 
> > this way:
> > +    EXCEPTION_REGISTRATION_RECORD catch_frame;
> >       cxx_frame_info frame_info;
> > Shouldn't the cxx_catch_cleanup just unregister the object that was 
> > registered in call_catch_block?

Here's a test case that demonstrate the problem with cur <= frame 
comparison:

	try {
		try { int *p = NULL; *p = 0x42; }
		catch (klass x) { throw 1; }
	} catch (int i) { }

	try { throw 1; }
	catch(...) {}

Cheers,
Piotr