Re: [FFmpeg-devel] [PATCH v1] avcodec/jpeg2000htdec: check if block decoding will exceed internal precision

[Pierre-Anthony Lemieux <pal@sandflow.com>]

On Sat, Aug 12, 2023 at 1:31 PM Pierre-Anthony Lemieux <pal@sandflow.com> wrote:
>
> On Sat, Aug 12, 2023 at 11:39 AM Michael Niedermayer
> <michael@niedermayer.cc> wrote:
> >
> > On Thu, Aug 10, 2023 at 04:48:56PM -0700, pal@sandflow.com wrote:
> > > From: Pierre-Anthony Lemieux <pal@palemieux.com>
> > >
> > > Intended to replace https://patchwork.ffmpeg.org/project/ffmpeg/patch/20230802000135.26482-3-michael@niedermayer.cc/
> > > with a more accurate block decoding magnitude bound.
> > >
> > > ---
> > >  libavcodec/jpeg2000htdec.c | 32 +++++++++++++++++++++++++++++++-
> > >  1 file changed, 31 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/libavcodec/jpeg2000htdec.c b/libavcodec/jpeg2000htdec.c
> > > index 2c4cea5dd9..713dba17e3 100644
> > > --- a/libavcodec/jpeg2000htdec.c
> > > +++ b/libavcodec/jpeg2000htdec.c
> > > @@ -572,6 +572,14 @@ static int jpeg2000_decode_ht_cleanup_segment(const Jpeg2000DecoderContext *s,
> > >
> > >      const uint8_t *vlc_buf = Dcup + Pcup;
> > >
> > > +    /*
> > > +     * Bound on the recision needed to process the codeblock. The number of
> > > +     * decoded bit planes is equal to at most cblk->zbp + 2 since S_blk = P if
> > > +     * there are no placeholder passes or HT Sets and P = cblk->zbp. See Rec.
> > > +     * ITU-T T.814, 7.6.
> > > +     */
> > > +    int maxbp = cblk->zbp + 2;
> > > +
> > >      /* convert to raster-scan */
> > >      const uint16_t is_border_x = width % 2;
> > >      const uint16_t is_border_y = height % 2;
> > > @@ -590,6 +598,10 @@ static int jpeg2000_decode_ht_cleanup_segment(const Jpeg2000DecoderContext *s,
> > >          goto free;
> > >      }
> > >
> > > +    /* do we have enough precision, assuming a 32-bit decoding path */
> > > +    if (maxbp >= 32)
> > > +        return AVERROR_INVALIDDATA;
> >
> > doesnt this need a goto free ?
>
> Yes. Just pushed v2 of the patchset.

I meant "sent it to this reflector".

>
> >
> > thx
> >
> > [...]
> >
> > --
> > Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> >
> > No human being will ever know the Truth, for even if they happen to say it
> > by chance, they would not even known they had done so. -- Xenophanes
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