From 9c713f30e4913a28d93eb37ea5db7f62be4c0ef6 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Wed, 3 Oct 2012 16:06:23 +0200
Subject: [PATCH] parser: fix large overreads

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Justin Ruggles <justin.ruggles@gmail.com>

(cherry picked from commit 096abfa15052977eed93f0b5e01afd2d47c53c1f)

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
---
 libavcodec/parser.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libavcodec/parser.c b/libavcodec/parser.c
index 03f548ef6a..aeabf690f0 100644
--- a/libavcodec/parser.c
+++ b/libavcodec/parser.c
@@ -261,7 +261,9 @@ int ff_combine_frame(ParseContext *pc, int next, const uint8_t **buf, int *buf_s
         if(!new_buffer)
             return AVERROR(ENOMEM);
         pc->buffer = new_buffer;
-        memcpy(&pc->buffer[pc->index], *buf, next + FF_INPUT_BUFFER_PADDING_SIZE );
+        if (next > -FF_INPUT_BUFFER_PADDING_SIZE)
+            memcpy(&pc->buffer[pc->index], *buf,
+                   next + FF_INPUT_BUFFER_PADDING_SIZE);
         pc->index = 0;
         *buf= pc->buffer;
     }