[FFmpeg-cvslog] avcodec/jpeg2000dec: Move reslevelno check before use in case JPEG2000_PGOD_RPCL

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sun Jul 26 19:41:30 2020 +0200| [6ea8f03bf4b7bca2f4db28ea57696584e2560e20] | committer: Michael Niedermayer

avcodec/jpeg2000dec: Move reslevelno check before use in case JPEG2000_PGOD_RPCL

Fixes: division by zero
Fixes: 24201/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEG2000_fuzzer-5665813827420160
Fixes: 24245/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEG2000_fuzzer-6285831682392064

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Gautam Ramakrishnan <gautamramk at gmail.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=6ea8f03bf4b7bca2f4db28ea57696584e2560e20
---

 libavcodec/jpeg2000dec.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index a470cf47da..b168e52db6 100644
--- a/libavcodec/jpeg2000dec.c
+++ b/libavcodec/jpeg2000dec.c
@@ -1401,12 +1401,12 @@ static int jpeg2000_decode_packets_po_iteration(Jpeg2000DecoderContext *s, Jpeg2
                         if (!s->cdx[compno] || !s->cdy[compno])
                             return AVERROR_INVALIDDATA;
 
-                        trx0 = ff_jpeg2000_ceildiv(tile->coord[0][0], s->cdx[compno] << reducedresno);
-                        try0 = ff_jpeg2000_ceildiv(tile->coord[1][0], s->cdy[compno] << reducedresno);
-
                         if (reslevelno >= codsty->nreslevels)
                             continue;
 
+                        trx0 = ff_jpeg2000_ceildiv(tile->coord[0][0], s->cdx[compno] << reducedresno);
+                        try0 = ff_jpeg2000_ceildiv(tile->coord[1][0], s->cdy[compno] << reducedresno);
+
                         if (!(y % ((uint64_t)s->cdy[compno] << (rlevel->log2_prec_height + reducedresno)) == 0 ||
                              (y == tile->coord[1][0] && (try0 << reducedresno) % (1U << (reducedresno + rlevel->log2_prec_height)))))
                             continue;