From ce55e667facbaf0e7aa8d543b114b28d22c2a250 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Tue, 29 Oct 2013 16:12:01 +0100
Subject: [PATCH] avcodec/mpegvideo_enc: check that max_b_frames is not
 negative

Fixes crash found by saste
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
---
 libavcodec/mpegvideo_enc.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libavcodec/mpegvideo_enc.c b/libavcodec/mpegvideo_enc.c
index 9b503865c6..3db975c5ff 100644
--- a/libavcodec/mpegvideo_enc.c
+++ b/libavcodec/mpegvideo_enc.c
@@ -452,6 +452,11 @@ av_cold int ff_MPV_encode_init(AVCodecContext *avctx)
         av_log(avctx, AV_LOG_ERROR, "b frames not supported by codec\n");
         return -1;
     }
+    if (s->max_b_frames < 0) {
+        av_log(avctx, AV_LOG_ERROR,
+               "max b frames must be 0 or postive for mpegvideo based encoders\n");
+        return -1;
+    }
 
     if ((s->codec_id == AV_CODEC_ID_MPEG4 ||
          s->codec_id == AV_CODEC_ID_H263  ||