[FFmpeg-devel] [PATCH] avcodec/h264_ps: Fix copying oversized pps data

[Hendrik Leppkes]

On Fri, Oct 2, 2015 at 9:49 PM, wm4 <nfxjfg at googlemail.com> wrote:
> On Fri, 2 Oct 2015 21:41:59 +0200
> Michael Niedermayer <michaelni at gmx.at> wrote:
>
>> On Fri, Oct 02, 2015 at 09:23:04PM +0200, wm4 wrote:
>> > On Fri,  2 Oct 2015 21:14:57 +0200
>> > Michael Niedermayer <michaelni at gmx.at> wrote:
>> >
>> > > From: Michael Niedermayer <michael at niedermayer.cc>
>> > >
>> > > Fixes: https://trac.ffmpeg.org/attachment/ticket/685/movie.264
>> > >
>> > > In the available testcase the actual PPS only uses a few bits
>> > > while there are 7kbyte of apparently random data after it
>> > >
>> > > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
>> > > ---
>> > >  libavcodec/h264_ps.c |    4 ++--
>> > >  1 file changed, 2 insertions(+), 2 deletions(-)
>> > >
>> > > diff --git a/libavcodec/h264_ps.c b/libavcodec/h264_ps.c
>> > > index fd16a95..0dca5f0 100644
>> > > --- a/libavcodec/h264_ps.c
>> > > +++ b/libavcodec/h264_ps.c
>> > > @@ -611,8 +611,8 @@ int ff_h264_decode_picture_parameter_set(H264Context *h, int bit_length)
>> > >          return AVERROR(ENOMEM);
>> > >      pps->data_size = h->gb.buffer_end - h->gb.buffer;
>> > >      if (pps->data_size > sizeof(pps->data)) {
>> > > -        ret = AVERROR_INVALIDDATA;
>> > > -        goto fail;
>> > > +        av_log(h->avctx, AV_LOG_WARNING, "Truncating likely oversized PPS\n");
>> > > +        pps->data_size = sizeof(pps->data);
>> > >      }
>> > >      memcpy(pps->data, h->gb.buffer, pps->data_size);
>> > >      pps->sps_id = get_ue_golomb_31(&h->gb);
>> >
>> > That was quick.
>> >
>>
>> > Should the same be done for SPS?
>>
>> i dont know
>>
>
> I'd say it would be good for symmetry.
>

Its a new error condition which wouldn't affect 99% of all users, so
its probably best to switch it to a warning as well and hope for the
best.

- Hendrik