linux-kernel - [PATCH 4.4 047/146] ipv6: Fix mem leak in rt6i

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Date:	Mon, 25 Jul 2016 13:55:02 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Martin KaFai Lau <kafai@...com>,
	Petr Novopashenniy <pety@...net.ru>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.4 047/146] ipv6: Fix mem leak in rt6i_pcpu

4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Martin KaFai Lau <kafai@...com>

[ Upstream commit 903ce4abdf374e3365d93bcb3df56c62008835ba ]

It was first reported and reproduced by Petr (thanks!) in
https://bugzilla.kernel.org/show_bug.cgi?id=119581

free_percpu(rt->rt6i_pcpu) used to always happen in ip6_dst_destroy().

However, after fixing a deadlock bug in
commit 9c7370a166b4 ("ipv6: Fix a potential deadlock when creating pcpu rt"),
free_percpu() is not called before setting non_pcpu_rt->rt6i_pcpu to NULL.

It is worth to note that rt6i_pcpu is protected by table->tb6_lock.

kmemleak somehow did not report it.  We nailed it down by
observing the pcpu entries in /proc/vmallocinfo (first suggested
by Hannes, thanks!).

Signed-off-by: Martin KaFai Lau <kafai@...com>
Fixes: 9c7370a166b4 ("ipv6: Fix a potential deadlock when creating pcpu rt")
Reported-by: Petr Novopashenniy <pety@...net.ru>
Tested-by: Petr Novopashenniy <pety@...net.ru>
Acked-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc: Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc: Petr Novopashenniy <pety@...net.ru>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv6/ip6_fib.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -179,6 +179,7 @@ static void rt6_free_pcpu(struct rt6_inf
 		}
 	}
 
+	free_percpu(non_pcpu_rt->rt6i_pcpu);
 	non_pcpu_rt->rt6i_pcpu = NULL;
 }