[3.11.y.z extended stable] Patch "ipv6: fix possible seqlock deadlock in ip6_finish_output2" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Wed Dec 11 14:40:30 UTC 2013


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

    ipv6: fix possible seqlock deadlock in ip6_finish_output2

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

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

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From ee7693f77410ace60e0c8b3acefaa1612afe2036 Mon Sep 17 00:00:00 2001
From: Hannes Frederic Sowa <hannes at stressinduktion.org>
Date: Fri, 29 Nov 2013 06:39:44 +0100
Subject: ipv6: fix possible seqlock deadlock in ip6_finish_output2

commit 7f88c6b23afbd31545c676dea77ba9593a1a14bf upstream.

IPv6 stats are 64 bits and thus are protected with a seqlock. By not
disabling bottom-half we could deadlock here if we don't disable bh and
a softirq reentrantly updates the same mib.

Cc: Eric Dumazet <eric.dumazet at gmail.com>
Signed-off-by: Hannes Frederic Sowa <hannes at stressinduktion.org>
Acked-by: Eric Dumazet <edumazet at google.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/ipv6/ip6_output.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index f80f2fa..e50a9e3 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -141,8 +141,8 @@ static int ip6_finish_output2(struct sk_buff *skb)
 	}
 	rcu_read_unlock_bh();

-	IP6_INC_STATS_BH(dev_net(dst->dev),
-			 ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
+	IP6_INC_STATS(dev_net(dst->dev),
+		      ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
 	kfree_skb(skb);
 	return -EINVAL;
 }
--
1.8.3.2





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