From: Steffen Klassert <steffen.klassert@secunet•com>
To: Xianpeng Zhao <673321875@qq•com>
Cc: netdev <netdev@vger•kernel.org>, alan <alan@lxorguk•ukuu.org.uk>
Subject: Re: Fw:[Bug 70471] xfrm policy node will double unlink.
Date: Tue, 18 Feb 2014 09:37:38 +0100 [thread overview]
Message-ID: <20140218083737.GB32371@secunet.com> (raw)
In-Reply-To: <tencent_0D7FA5355C7998793C100B23@qq.com>
On Tue, Feb 18, 2014 at 10:55:57AM +0800, Xianpeng Zhao wrote:
> Hi Group,
> I found a problem about xfrm policy.
>
> In corner case, xfrm policy node will be double unlinked from the list.
>
> The scenario like this:
> In thread context, After removed the node from list, before remove the xfrm policy expire timer. At this point, a timer interrupt come, and call the run_timer_softirq to execute the xfrm_policy_timer to remove the expired policy node; because this policy node had already removed from list. this remove will cause the node double unlinked.
Good catch!
I wonder why I've never seen this. Do you have a reproducer for this bug?
Looks like it is sufficient to reinitialize the bydst hlist in
__xfrm_policy_unlink(). Then hlist_unhashed() will notice that
this policy is not linked.
Does the patch below help?
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 121399d..225f439 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1156,7 +1156,7 @@ 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]--;
next prev parent reply other threads:[~2014-02-18 8:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-18 2:55 Fw:[Bug 70471] xfrm policy node will double unlink Xianpeng Zhao
2014-02-18 8:37 ` Steffen Klassert [this message]
2014-02-19 2:07 ` Xianpeng Zhao
2014-02-19 11:43 ` Steffen Klassert
2014-02-20 2:01 ` Xianpeng Zhao
2014-02-21 7:35 ` Steffen Klassert
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