netdev - [PATCH net-next 5/6] neigh: neigh dead and timer variables should be protected under its lock

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Date:	Fri, 15 May 2015 14:55:45 +0800
From:	Ying Xue <ying.xue@...driver.com>
To:	<netdev@...r.kernel.org>
CC:	<eric.dumazet@...il.com>, <alexei@...estorage.com>,
	<joern@...estorage.com>, <ja@....bg>, <davem@...emloft.net>
Subject: [PATCH net-next 5/6] neigh: neigh dead and timer variables should be protected under its lock

As neigh lock is not taken before its variables like dead and timer
are used in neigh_destroy(), this is unsafe for us. The commit allows
neigh lock to cover all area of using them.

Signed-off-by: Ying Xue <ying.xue@...driver.com>
---
 net/core/neighbour.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 8a438fc..67a0e42 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -687,9 +687,11 @@ void neigh_destroy(struct neighbour *neigh)
 
 	NEIGH_CACHE_STAT_INC(neigh->tbl, destroys);
 
+	write_lock_bh(&neigh->lock);
 	if (!neigh->dead) {
 		pr_warn("Destroying alive neighbour %p\n", neigh);
 		dump_stack();
+		write_unlock_bh(&neigh->lock);
 		return;
 	}
 
@@ -698,7 +700,6 @@ void neigh_destroy(struct neighbour *neigh)
 		dump_stack();
 	}
 
-	write_lock_bh(&neigh->lock);
 	__skb_queue_purge(&neigh->arp_queue);
 	write_unlock_bh(&neigh->lock);
 	neigh->arp_queue_len_bytes = 0;
-- 
1.7.9.5

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