[FFmpeg-cvslog] libavcodec/jpeg2000dec: Fix codeblock decode check

[Gautam Ramakrishnan]

ffmpeg | branch: master | Gautam Ramakrishnan <gautamramk at gmail.com> | Thu Jul 23 22:59:10 2020 +0530| [ff5b9ece4290d245ba3bbf110d90f3f432dda3cc] | committer: Michael Niedermayer

libavcodec/jpeg2000dec: Fix codeblock decode check

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

Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=ff5b9ece4290d245ba3bbf110d90f3f432dda3cc
---

 libavcodec/jpeg2000dec.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index e941ebb5d0..a470cf47da 100644
--- a/libavcodec/jpeg2000dec.c
+++ b/libavcodec/jpeg2000dec.c
@@ -1754,9 +1754,13 @@ 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",
-               cblk->data + cblk->length - 2*(term_cnt < cblk->nb_terminations) - t1->mqc.bp);
+               cblk->data + cblk->length - 2 - t1->mqc.bp);
+    }
+
+    if (cblk->data + cblk->length < t1->mqc.bp) {
+        av_log(s->avctx, AV_LOG_WARNING, "Synthetic End of Stream Marker Read.\n");
     }
 
     return 1;