Re: [FFmpeg-devel] [PATCH v1] avcodec/cbs_vp8: Improve the bitstream position check

["Dai, Jianhui J" <jianhui.j.dai-at-intel.com@ffmpeg.org>]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of Dai,
> Jianhui J
> Sent: Friday, February 23, 2024 8:43 AM
> To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH v1] avcodec/cbs_vp8: Improve the
> bitstream position check
> 
> 
> 
> > -----Original Message-----
> > From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of Dai,
> > Jianhui J
> > Sent: Thursday, January 25, 2024 8:54 AM
> > To: ffmpeg-devel@ffmpeg.org
> > Subject: [FFmpeg-devel] [PATCH v1] avcodec/cbs_vp8: Improve the
> > bitstream position check
> >
> > The VP8 compressed header may not be byte-aligned due to boolean
> > coding. Use bitwise comparison to prevent the potential overread.
> >
> > Signed-off-by: Jianhui Dai <jianhui.j.dai@intel.com>
> > ---
> >  libavcodec/cbs_vp8.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/libavcodec/cbs_vp8.c b/libavcodec/cbs_vp8.c index
> > 065156c248..13acad3724 100644
> > --- a/libavcodec/cbs_vp8.c
> > +++ b/libavcodec/cbs_vp8.c
> > @@ -327,9 +327,10 @@ static int
> > cbs_vp8_read_unit(CodedBitstreamContext
> > *ctx,
> >      if (err < 0)
> >          return err;
> >
> > +    // Position may not be byte-aligned after compressed header; using bits
> > +    // count comparison for accuracy.
> >      pos = get_bits_count(&gbc);
> > -    pos /= 8;
> > -    av_assert0(pos <= unit->data_size);
> > +    av_assert0(pos <= unit->data_size * 8);
> >
> >      frame->data_ref = av_buffer_ref(unit->data_ref);
> >      if (!frame->data_ref)
> 
> Ping reviewers to help to apply.
> 
> The review history can be found here:
> https://patchwork.ffmpeg.org/project/ffmpeg/patch/CH3PR11MB793797554CD
> B411074364733B1742@CH3PR11MB7937.namprd11.prod.outlook.com/

@Ronald (rsbultje@gmail.com), @Andreas (andreas.rheinhardt@outlook.com)

Could you please help to apply these 2 fixes?

[FFmpeg-devel,v1] avcodec/cbs_vp8: Improve the bitstream position check - Patchwork
https://patchwork.ffmpeg.org/project/ffmpeg/patch/DS7PR11MB7949CF2C01F31B4B8597EC61B17A2@DS7PR11MB7949.namprd11.prod.outlook.com/

[FFmpeg-devel,v1] avcodec/cbs_vp8: Use little endian in fixed() - Patchwork
https://patchwork.ffmpeg.org/project/ffmpeg/patch/DS7PR11MB79499AF0B5FB03FBF1876EFCB17A2@DS7PR11MB7949.namprd11.prod.outlook.com/

> 
> > --
> > 2.25.1
> >
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