> -----Original Message----- > From: ffmpeg-devel [mailto:ffmpeg-devel-boun...@ffmpeg.org] On Behalf Of > Andreas Rheinhardt > Sent: Thursday, June 13, 2019 2:11 AM > To: ffmpeg-devel@ffmpeg.org > Subject: Re: [FFmpeg-devel] [PATCH v4] vaapi_encode_mjpeg: fix bad component > id bug > > Dominik 'Rathann' Mierzejewski: > > On Friday, 07 June 2019 at 23:45, U. Artie Eoff wrote: > >> The compound literals assigned to "components" > >> only exist within the scope of the if/else > >> block (thanks Mark Thompson for the better > >> explanation). > >> > >> Thus, after this if/else block, "components" > >> ends up pointing to an arbitrary/undefined > >> array. With some compilers and depending on > >> optimization settings, these arbitrary values > >> may end up being the same value (i.e. 0 with > >> GNU GCC 9.x). Unfortunately, the GNU GCC > >> compiler, at least, never prints any warnings > >> about this. > >> > >> This patch fixes this issue by assigning the > >> constant arrays to local variables at function > >> scope and then pointing "components" to those > >> as necessary. > >> > >> Fixes #7915 > > > > Brilliant detective work, Artie. Could you open a bug report with gcc > > upstream? A case like this should get an explicit warning from gcc like > > you pointed out. > > > > Regards, > > Dominik > > > A request for this has already been opened [1]. > It seems that this is also responsible for filesystem corruption on > linux when using a SSD cache + HDD combination (see [2]). >
According to comments in the gcc request, it looks like we could use " -fsanitize=address". Anyone care to test it out to see if it will work? > - Andreas > > [1]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89990 > [2]: https://bugzilla.kernel.org/show_bug.cgi?id=203573 > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
