From 579795b2049bc8b0f291b302e7ab24f9561eaf24 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Fri, 23 Jan 2015 15:03:40 +0100
Subject: [PATCH] avfilter/af_channelmap: Check for missing argument in
 get_channel_idx()

Fixes null pointer dereference

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
---
 libavfilter/af_channelmap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavfilter/af_channelmap.c b/libavfilter/af_channelmap.c
index c3454c5b69..2a43c12af2 100644
--- a/libavfilter/af_channelmap.c
+++ b/libavfilter/af_channelmap.c
@@ -93,6 +93,8 @@ static int get_channel_idx(char **map, int *ch, char delim, int max_ch)
     int n = 0;
     if (!next && delim == '-')
         return AVERROR(EINVAL);
+    if (!*map)
+        return AVERROR(EINVAL);
     len = strlen(*map);
     sscanf(*map, "%d%n", ch, &n);
     if (n != len)