Subject: [PATCH 6/6] ipv6: Fix mem leak in rt6i_pcpu

From: Martin KaFai Lau <[email-masked]>
Date: Tue, 5 Jul 2016 12:10:23 -0700

[ 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 <[email-masked]>
Fixes: 9c7370a166b4 ("ipv6: Fix a potential deadlock when creating pcpu rt")
Reported-by: Petr Novopashenniy <[email-masked]>
Tested-by: Petr Novopashenniy <[email-masked]>
Acked-by: Hannes Frederic Sowa <[email-masked]>
Cc: Hannes Frederic Sowa <[email-masked]>
Cc: Petr Novopashenniy <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 net/ipv6/ip6_fib.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index ea071fa..c26fac2 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -177,6 +177,7 @@ static void rt6_free_pcpu(struct rt6_info *non_pcpu_rt)
 		}
 	}
 
+	free_percpu(non_pcpu_rt->rt6i_pcpu);
 	non_pcpu_rt->rt6i_pcpu = NULL;
 }
 
-- 
2.1.0