From c9a36f12e6656a106895a30f33d39d3169de82c5 Mon Sep 17 00:00:00 2001
From: Michael Borgelt <mb@teuto.net>
Date: Tue, 13 Sep 2011 11:59:09 +0200
Subject: [PATCH] Fix Use of uninitialized value in substr at
 /usr/share/perl5/SNMP/Info/IPv6.pm line 113. It is caused by an empty mac in
 local loopback interface on cisco devices.

Signed-off-by: Jeroen van Ingen <jeroen@utwente.nl>
---
 Info/IPv6.pm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Info/IPv6.pm b/Info/IPv6.pm
index b54e446e..c1f2eb5c 100644
--- a/Info/IPv6.pm
+++ b/Info/IPv6.pm
@@ -108,7 +108,7 @@ sub ipv6_n2p_mac {
                 $v6addr = join('.', $addrtype, $addrsize, $v6addr);
                 $addrtype = 2;
             }
-            if ($addrtype == 2) { # IPv6
+            if (($addrtype == 2) && (defined $phys_addr->{$row})) { # IPv6
                 $return->{$row} = substr($phys_addr->{$row}, 0, 17);
             }
         }