From a06cd0283eeadccff7a0e8a9214c01e816cfcad2 Mon Sep 17 00:00:00 2001
From: James Almer <jamrial@gmail.com>
Date: Mon, 18 Mar 2019 17:25:58 -0300
Subject: [PATCH] avcodec/hevcdec: decode at most one slice reporting being the
 first in the picture

Fixes deadlocks when decoding packets containing more than one of the aforementioned
slices when using frame threads.

Tested-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>
(cherry picked from commit 70c8c8a818f39bc262565ec29fae2baffb3e1660)
---
 libavcodec/hevc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/libavcodec/hevc.c b/libavcodec/hevc.c
index f8aeb63aa1..eb052b55ea 100644
--- a/libavcodec/hevc.c
+++ b/libavcodec/hevc.c
@@ -2795,6 +2795,10 @@ static int decode_nal_unit(HEVCContext *s, const H2645NAL *nal)
         }
 
         if (s->sh.first_slice_in_pic_flag) {
+            if (s->ref) {
+                av_log(s->avctx, AV_LOG_ERROR, "Two slices reporting being the first in the same frame.\n");
+                goto fail;
+            }
             ret = hevc_frame_start(s);
             if (ret < 0)
                 return ret;