netdev - Re: [Patch net] ipt_CLUSTERIP: fix a race condition of proc file creation

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Message-ID: <20180208165826.ywawymn6aqhmtal2@salvia>
Date:   Thu, 8 Feb 2018 17:58:26 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     netdev@...r.kernel.org, netfilter-devel@...r.kernel.org,
        pabeni@...hat.com, Xin Long <lucien.xin@...il.com>
Subject: Re: [Patch net] ipt_CLUSTERIP: fix a race condition of proc file
 creation

On Wed, Feb 07, 2018 at 09:59:17PM -0800, Cong Wang wrote:
> There is a race condition between clusterip_config_entry_put()
> and clusterip_config_init(), after we release the spinlock in
> clusterip_config_entry_put(), a new proc file with a same IP could
> be created immediately since it is already removed from the configs
> list, therefore it triggers this warning:
> 
> ------------[ cut here ]------------
> proc_dir_entry 'ipt_CLUSTERIP/172.20.0.170' already registered
> WARNING: CPU: 1 PID: 4152 at fs/proc/generic.c:330 proc_register+0x2a4/0x370 fs/proc/generic.c:329
> Kernel panic - not syncing: panic_on_warn set ...
> 
> As a quick fix, just move the proc_remove() inside the spinlock.

Applied, thanks.