[FFmpeg-cvslog] avcodec/jpeg2000dec: Skip init for component in CPRL if nothing is to be done

[Michael Niedermayer]

ffmpeg | branch: release/4.0 | Michael Niedermayer <michael at niedermayer.cc> | Fri May  4 19:11:36 2018 +0200| [87e9f5e1186c71a5bf18d15bd816039bd77d6954] | committer: Michael Niedermayer

avcodec/jpeg2000dec: Skip init for component in CPRL if nothing is to be done

Fixes: assertion failure
Fixes: 7949/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEG2000_fuzzer-4819602782552064

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit a96c131eb53b00de154f4773d96a3b323ea3daed)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=87e9f5e1186c71a5bf18d15bd816039bd77d6954
---

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

diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index 5414ce5655..94be6ba3e5 100644
--- a/libavcodec/jpeg2000dec.c
+++ b/libavcodec/jpeg2000dec.c
@@ -1156,6 +1156,9 @@ static int jpeg2000_decode_packets_po_iteration(Jpeg2000DecoderContext *s, Jpeg2
             step_x = 32;
             step_y = 32;
 
+            if (RSpoc > FFMIN(codsty->nreslevels, REpoc))
+                continue;
+
             for (reslevelno = RSpoc; reslevelno < FFMIN(codsty->nreslevels, REpoc); reslevelno++) {
                 uint8_t reducedresno = codsty->nreslevels - 1 -reslevelno; //  ==> N_L - r
                 Jpeg2000ResLevel *rlevel = comp->reslevel + reslevelno;