Fix CVE-2017-14633:

https://gitlab.xiph.org/xiph/vorbis/issues/2329
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-14633

Patch copied from upstream source repository:

https://gitlab.xiph.org/xiph/vorbis/commit/a79ec216cd119069c68b8f3542c6a425a74ab993

From a79ec216cd119069c68b8f3542c6a425a74ab993 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Guido=20G=C3=BCnther?= <agx@sigxcpu.org>
Date: Tue, 31 Oct 2017 18:32:46 +0100
Subject: [PATCH] CVE-2017-14633: Don't allow for more than 256 channels

Otherwise

 for(i=0;i<vi->channels;i++){
      /* the encoder setup assumes that all the modes used by any
         specific bitrate tweaking use the same floor */
      int submap=info->chmuxlist[i];

overreads later in mapping0_forward since chmuxlist is a fixed array of
256 elements max.
---
 lib/info.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/info.c b/lib/info.c
index fe759ed..7bc4ea4 100644
--- a/lib/info.c
+++ b/lib/info.c
@@ -588,7 +588,7 @@ int vorbis_analysis_headerout(vorbis_dsp_state *v,
   oggpack_buffer opb;
   private_state *b=v->backend_state;
 
-  if(!b||vi->channels<=0){
+  if(!b||vi->channels<=0||vi->channels>256){
     ret=OV_EFAULT;
     goto err_out;
   }
-- 
2.15.1

