[FFmpeg-cvslog] avcodec/h264dec: Clear ref_count on slice header processing failure

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Fri Jan 27 00:14:02 2017 +0100| [f28299da8d06f0f3fe0195edff727b246d0a34cf] | committer: Michael Niedermayer

avcodec/h264dec: Clear ref_count on slice header processing failure

Fixes using freed memory
Introduced in 744801989099df26e90b00062c645969c5347533
Fixes: 471/fuzz-1-ffmpeg_VIDEO_AV_CODEC_ID_H264_fuzzer

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=f28299da8d06f0f3fe0195edff727b246d0a34cf
---

 libavcodec/h264dec.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libavcodec/h264dec.c b/libavcodec/h264dec.c
index 31db1db..0994b83 100644
--- a/libavcodec/h264dec.c
+++ b/libavcodec/h264dec.c
@@ -670,8 +670,11 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
         case H264_NAL_SLICE:
             h->has_slice = 1;
 
-            if ((err = ff_h264_queue_decode_slice(h, nal)))
+            if ((err = ff_h264_queue_decode_slice(h, nal))) {
+                H264SliceContext *sl = h->slice_ctx + h->nb_slice_ctx_queued;
+                sl->ref_count[0] = sl->ref_count[1] = 0;
                 break;
+            }
 
             if (h->current_slice == 1) {
                 if (avctx->active_thread_type & FF_THREAD_FRAME && !h->avctx->hwaccel &&