From: "Su Yanjun <suyj.fnst@cn.fujitsu.com>" <suyj.fnst@cn.fujitsu.com>
To: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>,
Su Yanjun <suyanjun218@163.com>, <pablo@netfilter.org>,
<kadlec@blackhole.kfki.hu>, <fw@strlen.de>, <davem@davemloft.net>,
<netfilter-devel@vger.kernel.org>, <coreteam@netfilter.org>,
<netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] netfilter: nf_ct_helper: Fix possible panic when nf_conntrack_helper_unregister is used in an unloadable module
Date: Fri, 1 Mar 2019 17:08:23 +0800 [thread overview]
Message-ID: <ddd00e53-266b-93cc-898f-d92b88366d4d@cn.fujitsu.com> (raw)
In-Reply-To: <e420b6c0-bebf-a2fc-a2ee-7b3e0023d833@cogentembedded.com>
On 2019/3/1 16:43, Sergei Shtylyov wrote:
> Hello!
>
> On 01.03.2019 8:56, Su Yanjun wrote:
>
>> From: Su Yanjun <suyj.fnst@cn.fujitsu.com>
>>
>> Because nf_conntrack_helper_unregister maybe used in an unloadable
>> module,
>> it uses 'synchronize_rcu' which may cause kernel panic.
>>
>> According to the artical:
>
> Article?
>
I got it.
>> RCU and Unloadable Modules
>> https://lwn.net/Articles/217484/
>>
>> When we have a heavy rcu callback load, then some of the callbacks
>> might be
>> deferred in order to allow other processing to proceed.
>> sychnorize_rcu does
>> not wait rcu callback complete and module may be unloaded before
>> callback
>> done.
>>
>> This patch uses rcu_barrier instead of synchronize_rcu will prevent this
> ^ that/which
> missed?
>
Yes.
>> situation.
>>
>> Signed-off-by: Su Yanjun <suyj.fnst@cn.fujitsu.com>
> [...]
>
> MBR, Sergei
>
>
Thanks.
Su
next prev parent reply other threads:[~2019-03-01 9:08 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-01 5:56 [PATCH] netfilter: nf_ct_helper: Fix possible panic when nf_conntrack_helper_unregister is used in an unloadable module Su Yanjun
2019-03-01 8:43 ` Sergei Shtylyov
2019-03-01 9:08 ` Su Yanjun <suyj.fnst@cn.fujitsu.com> [this message]
2019-03-08 15:59 ` Pablo Neira Ayuso
2019-03-14 3:20 ` Su Yanjun <suyj.fnst@cn.fujitsu.com>
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