[3.13.y-ckt stable] Patch "ipv6: do not delete previously existing ECMP routes if add fails" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    ipv6: do not delete previously existing ECMP routes if add fails

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt22.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 222a415bf68a6141fcd1e1b2b9147de5d2bd8e91 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michal=20Kube=C4=8Dek?= <mkubecek at suse.cz>
Date: Mon, 18 May 2015 20:53:55 +0200
Subject: ipv6: do not delete previously existing ECMP routes if add fails

commit 35f1b4e96b9258a3668872b1139c51e5a23eb876 upstream.

If adding a nexthop of an IPv6 multipath route fails, comment in
ip6_route_multipath() says we are going to delete all nexthops already
added. However, current implementation deletes even the routes it
hasn't even tried to add yet. For example, running

  ip route add 1234:5678::/64 \
      nexthop via fe80::aa dev dummy1 \
      nexthop via fe80::bb dev dummy1 \
      nexthop via fe80::cc dev dummy1

twice results in removing all routes first command added.

Limit the second (delete) run to nexthops that succeeded in the first
(add) run.

Fixes: 51ebd3181572 ("ipv6: add support of equal cost multipath (ECMP)")
Signed-off-by: Michal Kubecek <mkubecek at suse.cz>
Acked-by: Nicolas Dichtel <nicolas.dichtel at 6wind.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/ipv6/route.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 9502a60..2059f1e1 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2423,9 +2423,9 @@ static int ip6_route_multipath(struct fib6_config *cfg, int add)
 	int attrlen;
 	int err = 0, last_err = 0;

+	remaining = cfg->fc_mp_len;
 beginning:
 	rtnh = (struct rtnexthop *)cfg->fc_mp;
-	remaining = cfg->fc_mp_len;

 	/* Parse a Multipath Entry */
 	while (rtnh_ok(rtnh, remaining)) {
@@ -2455,6 +2455,7 @@ beginning:
 				 * next hops that have been already added.
 				 */
 				add = 0;
+				remaining = cfg->fc_mp_len - remaining;
 				goto beginning;
 			}
 		}
--
1.9.1