File 0001-avformat-avidec-Check-nb_streams-in-read_gab2_sub.patch of Package ffmpeg2

From 239f75d6c3dfbe4def80a12913d5737dd5a5bbcc Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Wed, 28 Sep 2016 16:14:08 +0200
Subject: [PATCH] avformat/avidec: Check nb_streams in read_gab2_sub()
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Fixes null pointer dereference
Fixes: 1/null_point.avi

Found-by: 连一汉 <lianyihan@360.cn>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 2679ad4773aa356e7c3da5c68bc81f02a194617f)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavformat/avidec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavformat/avidec.c b/libavformat/avidec.c
index 0ffe990..d2904ab 100644
--- a/libavformat/avidec.c
+++ b/libavformat/avidec.c
@@ -1090,6 +1090,8 @@ static int read_gab2_sub(AVFormatContext *s, AVStream *st, AVPacket *pkt)
             goto error;
 
         if (!avformat_open_input(&ast->sub_ctx, "", sub_demuxer, NULL)) {
+            if (ast->sub_ctx->nb_streams != 1)
+                goto error;
             ff_read_packet(ast->sub_ctx, &ast->sub_pkt);
             *st->codec = *ast->sub_ctx->streams[0]->codec;
             ast->sub_ctx->streams[0]->codec->extradata = NULL;
-- 
2.6.6