linux-kernel - [ 089/143] ipv6: fix possible seqlock deadlock in ip6_finish

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Message-Id: <20140512003204.338950133@1wt.eu>
Date:	Mon, 12 May 2014 02:33:29 +0200
From:	Willy Tarreau <w@....eu>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	Eric Dumazet <edumazet@...gle.com>,
	"David S. Miller" <davem@...emloft.net>, Willy Tarreau <w@....eu>
Subject: [ 089/143] ipv6: fix possible seqlock deadlock in ip6_finish_output2

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

------------------

From: Hannes Frederic Sowa <hannes@...essinduktion.org>

[ Upstream commit 7f88c6b23afbd31545c676dea77ba9593a1a14bf ]

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@...il.com>
Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
Acked-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Willy Tarreau <w@....eu>
---
 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 bb63ffc..6ff4d07 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -91,8 +91,8 @@ static int ip6_output_finish(struct sk_buff *skb)
 	else if (dst->neighbour)
 		return dst->neighbour->output(skb);
 
-	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;
 
-- 
1.7.12.2.21.g234cd45.dirty



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