[FFmpeg-devel] [PATCH] avcodec/v4l2_m2m: handle the v4l2 eos event

[BYHYKCHKIO WEIINZWLM]

You're welcome. Can this bug help me apply for a CVE?

On Tue, Mar 17, 2020 at 12:20 PM Andriy Gelman <andriy.gelman at gmail.com>
wrote:

> On Mon, 16. Mar 10:03, Ming Qian wrote:
> > when the last frame of capture is dequeueed,
> > driver may send this V4L2_EVENT_EOS event,
> > if this event is received, then we can set the capture port done
>
> Please add to your commit message (or something similar depending on what
> you
> tested):
> "Without this patch the s5p-mfc often hangs at the end of encoding when
> flushing the
> capture buffers."
>
> >
> > Signed-off-by: Ming Qian <ming.qian at nxp.com>
> > ---
> >  libavcodec/v4l2_context.c |  5 +++++
> >  libavcodec/v4l2_m2m_dec.c | 10 ++++++++++
> >  libavcodec/v4l2_m2m_enc.c | 22 ++++++++++++++++++++++
> >  3 files changed, 37 insertions(+)
> >
> > diff --git a/libavcodec/v4l2_context.c b/libavcodec/v4l2_context.c
> > index 8110bbb555..c10862aa12 100644
> > --- a/libavcodec/v4l2_context.c
> > +++ b/libavcodec/v4l2_context.c
> > @@ -171,6 +171,11 @@ static int v4l2_handle_event(V4L2Context *ctx)
> >          return 0;
> >      }
> >
> > +    if (evt.type == V4L2_EVENT_EOS) {
> > +        ctx->done = 1;
> > +        return 0;
> > +    }
> > +
> >      if (evt.type != V4L2_EVENT_SOURCE_CHANGE)
> >          return 0;
> >
> > diff --git a/libavcodec/v4l2_m2m_dec.c b/libavcodec/v4l2_m2m_dec.c
> > index d666edffe4..4862a4c0e5 100644
> > --- a/libavcodec/v4l2_m2m_dec.c
> > +++ b/libavcodec/v4l2_m2m_dec.c
> > @@ -123,6 +123,16 @@ static int v4l2_prepare_decoder(V4L2m2mContext *s)
> >          }
> >      }
> >
>
> > +    memset(&sub, 0, sizeof(sub));
> > +    sub.type = V4L2_EVENT_EOS;
> > +    ret = ioctl(s->fd, VIDIOC_SUBSCRIBE_EVENT, &sub);
> > +    if (ret < 0) {
> > +        av_log(s->avctx, AV_LOG_ERROR,
> > +                "the v4l2 driver does not support
> VIDIOC_SUBSCRIBE_EVENT\n"
> > +                "you must provide an eos event to finish encode\n");
> > +        return ret;
> > +    }
> > +
> >      return 0;
> >  }
> >
> > diff --git a/libavcodec/v4l2_m2m_enc.c b/libavcodec/v4l2_m2m_enc.c
> > index 5b954f4435..3abdd47a4a 100644
> > --- a/libavcodec/v4l2_m2m_enc.c
> > +++ b/libavcodec/v4l2_m2m_enc.c
> > @@ -155,6 +155,24 @@ static int
> v4l2_check_b_frame_support(V4L2m2mContext *s)
> >      return AVERROR_PATCHWELCOME;
> >  }
> >
> > +static int v4l2_subscribe_eos_event(V4L2m2mContext *s)
> > +{
> > +    struct v4l2_event_subscription sub;
> > +    int ret;
> > +
> > +    memset(&sub, 0, sizeof(sub));
> > +    sub.type = V4L2_EVENT_EOS;
> > +    ret = ioctl(s->fd, VIDIOC_SUBSCRIBE_EVENT, &sub);
> > +    if (ret < 0) {
> > +        av_log(s->avctx, AV_LOG_ERROR,
> > +                "the v4l2 driver does not support
> VIDIOC_SUBSCRIBE_EVENT\n"
> > +                "you must provide an eos event to finish encode\n");
> > +        return ret;
> > +    }
> > +
> > +    return 0;
> > +}
> > +
> >  static int v4l2_prepare_encoder(V4L2m2mContext *s)
> >  {
> >      AVCodecContext *avctx = s->avctx;
> > @@ -164,6 +182,10 @@ static int v4l2_prepare_encoder(V4L2m2mContext *s)
> >      /**
> >       * requirements
> >       */
>
> > +    ret = v4l2_subscribe_eos_event(s);
> > +    if (ret)
> > +        return ret;
> > +
>
> I don't have a venus board to test, but it looks that the encoder doesn't
> support
> V4L2_EVENT_EOS. It ends up calling v4l2_ctrl_subscribe_event() [1], which
> returns EINVAL.
>
> So I would log the error message, but not fail. Same in the decoder init.
> Ideally, it would be good to also test on a venus board too.
>
> [1]
> https://github.com/torvalds/linux/blob/master/drivers/media/v4l2-core/v4l2-ctrls.c#L4565
>
> >      ret = v4l2_check_b_frame_support(s);
> >      if (ret)
> >          return ret;
> > --
> > 2.25.1
> >
>
> Thanks,
> --
> Andriy
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