Hi James,
Thanks for the review.
How about we add a new function in av1dec.c like this:
static inline int read_obu_header_with_size_flag(const uint8_t *buf, int
buf_size,
int64_t *obu_size, int *type);
then we can remove first two patches and check has_size_flag in the function.
I guess "out of array reads" will not happen in low overhead obu, since it
always prepare enough data the obu.
> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> On Behalf Of James
> Almer
> Sent: Thursday, August 6, 2020 10:03 PM
> To: ffmpeg-devel@ffmpeg.org
> Subject: Re: [FFmpeg-devel] [PATCH 2/5] av1_parser: do not check buf_size if
> we have size in obu header
>
> On 8/6/2020 5:04 AM, Xu Guangxin wrote:
> > for low overhead obu, we can't forsee the obu size. we can only get it
> > when we parsed the obu header.
> > ---
> > libavcodec/av1_parse.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/libavcodec/av1_parse.h b/libavcodec/av1_parse.h index
> > a3b39f039c..823bdedd5e 100644
> > --- a/libavcodec/av1_parse.h
> > +++ b/libavcodec/av1_parse.h
> > @@ -135,7 +135,7 @@ static inline int parse_obu_header(const uint8_t
> > *buf, int buf_size,
> >
> > size = *obu_size + *start_pos;
> >
> > - if (size > buf_size)
> > + if (!*has_size_flag && size > buf_size)
>
> This check was added in c27c7b49dc to fix out of array reads, so this change
> will
> surely reintroduce the issue.
>
> Also, when has_size_flag is 0, size will never be bigger than buf_size
> because it
> will be derived from it, meaning this change is the same as removing the check
> altogether.
>
> > return AVERROR_INVALIDDATA;
> >
> > return size;
> >
>
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