[FFmpeg-devel] [PATCH v4] libavcodec/cbs_av1: Add size check before parse obu

[Xiang, Haihao]

On Wed, 2022-09-21 at 17:41 +0800, Wenbin Chen wrote:
> cbs_av1_write_obu() check pbc size after parsing obu frame, and return
> AVERROR(ENOSPC) if pbc is small. pbc will be reallocated and this obu
> frame will be parsed again, but this may cause error because
> CodedBitstreamAV1Context has already been updated, for example
> ref_order_hint is updated and will not match the same obu frame. Now size
> check is added before parsing obu frame to avoid this error.
> 
> Signed-off-by: Wenbin Chen <wenbin.chen at intel.com>
> ---
>  libavcodec/cbs_av1.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/libavcodec/cbs_av1.c b/libavcodec/cbs_av1.c
> index 154d9156cf..9c51a8c7c8 100644
> --- a/libavcodec/cbs_av1.c
> +++ b/libavcodec/cbs_av1.c
> @@ -1075,6 +1075,9 @@ static int cbs_av1_write_obu(CodedBitstreamContext *ctx,
>          put_bits32(pbc, 0);
>      }
>  
> +    if (8 * (unit->data_size + obu->obu_size) > put_bits_left(pbc))
> +        return AVERROR(ENOSPC);
> +
>      td = NULL;
>      start_pos = put_bits_count(pbc);
>  

According to the comment in 
https://patchwork.ffmpeg.org/project/ffmpeg/patch/20220329082921.756174-1-wenbin.chen@intel.com/
, the error might still occur. I sent out 
https://ffmpeg.org/pipermail/ffmpeg-devel/2022-September/302127.html to restore
CodedBitstreamAV1Context before returning AVERROR(ENOSPC). Could you have a look
?

Thanks
Haihao