[vlc-devel] [PATCH] gme: fixed out-of-memory/out-of-range tests

[Piotr Fusik]

Dnia 2012-03-23 19:08 Rémi Denis-Courmont napisał(a):

>Le vendredi 23 mars 2012 19:00:04 Piotr Fusik, vous avez écrit :
>> Hello everyone, I'm new here. :)
>> 
>> Dnia 2012-03-23 18:49 Rémi Denis-Courmont napisał(a):
>> >Le vendredi 23 mars 2012 18:15:33 Piotr Fusik, vous avez écrit :
>> >> ---
>> >> 
>> >>  modules/demux/gme.c |    6 +++---
>> >>  1 files changed, 3 insertions(+), 3 deletions(-)
>> >> 
>> >> diff --git a/modules/demux/gme.c b/modules/demux/gme.c
>> >> index 464ba9e..8f56887 100644
>> >> --- a/modules/demux/gme.c
>> >> +++ b/modules/demux/gme.c
>> >> @@ -261,8 +261,8 @@ static int Control (demux_t *demux, int query,
>> 
>> va_list
>> 
>> >> args)
>> >> 
>> >>               || (sys->titlev[sys->track_id]->i_length == 0))
>> >>               || 
>> >>                  break;
>> >> 
>> >> -            int seek = (sys->titlev[sys->track_id]->i_length / 1000) 
*
>> >> pos; -            if (seek > INT_MAX || gme_seek (sys->emu, seek))
>> >> +            double seek = (sys->titlev[sys->track_id]->i_length / 
1000)
>> 
>> *
>> 
>> >> pos;
>> >> +            if (seek > INT_MAX || gme_seek (sys->emu, (int) seek))
>> >
>> >So signed overflow is undefined. Unsigned would be enough and avoid 
going
>> 
>> to
>> 
>> >FPU...
>> 
>> Correct me if I'm wrong, but I thought double->unsigned conversion is 
only
>> defined within the range of unsigned?
>
>Yeah? So?
>
>I mean, we do care about not crashing or exhibiting undefined behaviour. We 
>don't care about not playing corrupt or overly long files correctly.
>
>Unsigned should be enough to protect against undefined behaviour, even if 
it 
>might cause integer overflow, no?

That's right.

Piotr