netdev - Re: Fw:[Bug 70471] xfrm policy node will double unlink.

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Message-ID: <20140221073530.GH32371@secunet.com>
Date:	Fri, 21 Feb 2014 08:35:30 +0100
From:	Steffen Klassert <steffen.klassert@...unet.com>
To:	Xianpeng Zhao <673321875@...com>
CC:	netdev <netdev@...r.kernel.org>, alan <alan@...rguk.ukuu.org.uk>
Subject: Re: Fw:[Bug 70471] xfrm policy node will double unlink.

On Thu, Feb 20, 2014 at 10:01:19AM +0800, Xianpeng Zhao wrote:
> Sorry, I misunderstood your means in last mail.
>     I get your patch now. Later I will use your patch. 
> 

The patch below is what I plan to commit to the ipsec tree,
please test it. Thanks!

Subject: [PATCH] xfrm: Fix unlink race when policies are deleted.

When a policy is unlinked from the lists in thread context,
the xfrm timer can fire before we can mark this policy as dead.
So reinitialize the bydst hlist, then hlist_unhashed() will
notice that this policy is not linked and will avoid a
doulble unlink of that policy.

Reported-by: Xianpeng Zhao <673321875@...com>
Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
---
 net/xfrm/xfrm_policy.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 4b98b25..1d5c7bf 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1158,7 +1158,7 @@ static struct xfrm_policy *__xfrm_policy_unlink(struct xfrm_policy *pol,
 	if (hlist_unhashed(&pol->bydst))
 		return NULL;

-	hlist_del(&pol->bydst);
+	hlist_del_init(&pol->bydst);
 	hlist_del(&pol->byidx);
 	list_del(&pol->walk.all);
 	net->xfrm.policy_count[dir]--;
-- 
1.7.9.5

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