[FFmpeg-cvslog] avcodec/h264_slice: Disable slice threads if there are multiple access units in a packet

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sat Oct 31 21:36:00 2015 +0100| [507b01f89969601f15555f7416804fb691632cbb] | committer: Michael Niedermayer

avcodec/h264_slice: Disable slice threads if there are multiple access units in a packet

Fixes null pointer dereference
Fixes Ticket4977

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=507b01f89969601f15555f7416804fb691632cbb
---

 libavcodec/h264_slice.c |    9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/libavcodec/h264_slice.c b/libavcodec/h264_slice.c
index 3f41e9b..eceda8a 100644
--- a/libavcodec/h264_slice.c
+++ b/libavcodec/h264_slice.c
@@ -1177,6 +1177,15 @@ int ff_h264_decode_slice_header(H264Context *h, H264SliceContext *sl)
                 av_log(h->avctx, AV_LOG_ERROR, "Too many fields\n");
                 return AVERROR_INVALIDDATA;
             }
+            if (h->max_contexts > 1) {
+                if (!h->single_decode_warning) {
+                    av_log(h->avctx, AV_LOG_WARNING, "Cannot decode multiple access units as slice threads\n");
+                    h->single_decode_warning = 1;
+                }
+                h->max_contexts = 1;
+                return SLICE_SINGLETHREAD;
+            }
+
             if (h->cur_pic_ptr && FIELD_PICTURE(h) && h->first_field) {
                 ret = ff_h264_field_end(h, h->slice_ctx, 1);
                 h->current_slice = 0;