This is a note to let you know that I've just added the patch titled
ipv6: correctly add local routes when lo goes up
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipv6-correctly-add-local-routes-when-lo-goes-up.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Nov 10 16:42:45 CET 2016
From: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>
Date: Wed, 12 Oct 2016 10:10:40 +0200
Subject: ipv6: correctly add local routes when lo goes up
From: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>
[ Upstream commit a220445f9f4382c36a53d8ef3e08165fa27f7e2c ]
The goal of the patch is to fix this scenario:
ip link add dummy1 type dummy
ip link set dummy1 up
ip link set lo down ; ip link set lo up
After that sequence, the local route to the link layer address of dummy1 is
not there anymore.
When the loopback is set down, all local routes are deleted by
addrconf_ifdown()/rt6_ifdown(). At this time, the rt6_info entry still
exists, because the corresponding idev has a reference on it. After the rcu
grace period, dst_rcu_free() is called, and thus ___dst_free(), which will
set obsolete to DST_OBSOLETE_DEAD.
In this case, init_loopback() is called before dst_rcu_free(), thus
obsolete is still sets to something <= 0. So, the function doesn't add the
route again. To avoid that race, let's check the rt6 refcnt instead.
Fixes: 25fb6ca4ed9c ("net IPv6 : Fix broken IPv6 routing table after loopback down-up")
Fixes: a881ae1f625c ("ipv6: don't call addrconf_dst_alloc again when enable lo")
Fixes: 33d99113b110 ("ipv6: reallocate addrconf router for ipv6 address when lo device up")
Reported-by: Francesco Santoro <francesco.santoro@xxxxxxxxx>
Reported-by: Samuel Gauthier <samuel.gauthier@xxxxxxxxx>
CC: Balakumaran Kannan <Balakumaran.Kannan@xxxxxxxxxxx>
CC: Maruthi Thotad <Maruthi.Thotad@xxxxxxxxxxx>
CC: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>
CC: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
CC: Weilong Chen <chenweilong@xxxxxxxxxx>
CC: Gao feng <gaofeng@xxxxxxxxxxxxxx>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv6/addrconf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2916,7 +2916,7 @@ static void init_loopback(struct net_dev
* lo device down, release this obsolete dst and
* reallocate a new router for ifa.
*/
- if (sp_ifa->rt->dst.obsolete > 0) {
+ if (!atomic_read(&sp_ifa->rt->rt6i_ref)) {
ip6_rt_put(sp_ifa->rt);
sp_ifa->rt = NULL;
} else {
Patches currently in stable-queue which might be from nicolas.dichtel@xxxxxxxxx are
queue-4.4/ipv6-correctly-add-local-routes-when-lo-goes-up.patch
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