From 3ef6c5264b2590781b4ed556443ff49709dd45fb Mon Sep 17 00:00:00 2001
From: Anton Khirnov <anton@khirnov.net>
Date: Sat, 3 May 2014 10:44:17 +0200
Subject: [PATCH] a64: check that extradata exists before reading from it

---
 libavformat/a64.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libavformat/a64.c b/libavformat/a64.c
index 640e786..da8e310 100644
--- a/libavformat/a64.c
+++ b/libavformat/a64.c
@@ -35,6 +35,12 @@ static int a64_write_header(AVFormatContext *s)
         0x00, //charset_lifetime (multi only)
         0x00  //fps in 50/fps;
     };
+
+    if (avctx->extradata_size < 4) {
+        av_log(s, AV_LOG_ERROR, "Missing extradata\n");
+        return AVERROR(EINVAL);
+    }
+
     switch (avctx->codec->id) {
     case AV_CODEC_ID_A64_MULTI:
         header[2] = 0x00;
-- 
2.7.4