netdev - [PATCH net-next] neigh: fix a possible leak issue of neigh entry

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Message-ID: <1431495814-22759-1-git-send-email-ying.xue@windriver.com>
Date:	Wed, 13 May 2015 13:43:34 +0800
From:	Ying Xue <ying.xue@...driver.com>
To:	<netdev@...r.kernel.org>
CC:	<davem@...emloft.net>
Subject: [PATCH net-next] neigh: fix a possible leak issue of neigh entry

Once modifying a pending timer of a neighbour, it's insufficient to
post a warning message. Instead we should not take the neighbour's
reference count at the same time, otherwise, it causes an issue that
the neighbour cannot be freed forever.

Signed-off-by: Ying Xue <ying.xue@...driver.com>
---
 net/core/neighbour.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 3de6542..5595db3 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -164,10 +164,11 @@ static int neigh_forced_gc(struct neigh_table *tbl)
 
 static void neigh_add_timer(struct neighbour *n, unsigned long when)
 {
-	neigh_hold(n);
-	if (unlikely(mod_timer(&n->timer, when))) {
-		printk("NEIGH: BUG, double timer add, state is %x\n",
-		       n->nud_state);
+	if (likely(!mod_timer(&n->timer, when))) {
+		neigh_hold(n);
+	} else {
+		pr_warn("NEIGH: BUG, double timer add, state is %x\n",
+			n->nud_state);
 		dump_stack();
 	}
 }
-- 
1.7.9.5

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