On Thu, Jul 23, 2020 at 7:56 PM Michael Niedermayer
<mich...@niedermayer.cc> wrote:
>
> On Tue, Jul 21, 2020 at 11:37:13PM +0530, gautamr...@gmail.com wrote:
> > From: Gautam Ramakrishnan <gautamr...@gmail.com>
> >
> > The codeblock decoder checks whether the mqc decoder
> > has decoded the right number of bytes. However, this
> > check does not account for the fact that the mqc encoder's
> > flush routine adds 2 bytes of data which does not have to be
> > read by the decoder. The check is modified to account for
> > this. This patch solves issue #4827
> > ---
> > libavcodec/jpeg2000dec.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
> > index f5ad8402fb..5e9e97eb6a 100644
> > --- a/libavcodec/jpeg2000dec.c
> > +++ b/libavcodec/jpeg2000dec.c
> > @@ -1753,9 +1753,9 @@ static int decode_cblk(Jpeg2000DecoderContext *s,
> > Jpeg2000CodingStyle *codsty,
> > pass_cnt ++;
> > }
> >
> > - if (cblk->data + cblk->length - 2*(term_cnt < cblk->nb_terminations)
> > != t1->mqc.bp) {
> > + if (cblk->data + cblk->length - 2 > t1->mqc.bp) {
> > av_log(s->avctx, AV_LOG_WARNING, "End mismatch
> > %"PTRDIFF_SPECIFIER"\n",
>
> This changes a equals check to a larger than check, so it removes checking
> in one direction. The commit message doesnt explain this sufficiently i think
>
I think a good solution would be to add a check in the other direction
and warn when the added
0xFF bytes are read.
> thx
>
> [...]
> --
> Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Concerning the gods, I have no means of knowing whether they exist or not
> or of what sort they may be, because of the obscurity of the subject, and
> the brevity of human life -- Protagoras
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--
-------------
Gautam |
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