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From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>,
	Florian Westphal <fw@strlen.de>,
	NetFilter <netfilter-devel@vger.kernel.org>,
	syzbot <syzbot+d195fd3b9a364ddd6731@syzkaller.appspotmail.com>
Subject: Re: [Patch nf] netfilter: xt_hashlimit: unregister proc file before releasing mutex
Date: Tue, 18 Feb 2020 23:05:07 +0100	[thread overview]
Message-ID: <20200218220507.cqlhd4kj4ukyjhuu@salvia> (raw)
In-Reply-To: <CAM_iQpWfb7xgd2LuRmaXhRSJskJPsupFk0A7=dRXtMEjZJjr3w@mail.gmail.com>

On Tue, Feb 18, 2020 at 01:40:26PM -0800, Cong Wang wrote:
> On Tue, Feb 18, 2020 at 1:35 PM Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> >
> > On Wed, Feb 12, 2020 at 10:53:52PM -0800, Cong Wang wrote:
> > > Before releasing the global mutex, we only unlink the hashtable
> > > from the hash list, its proc file is still not unregistered at
> > > this point. So syzbot could trigger a race condition where a
> > > parallel htable_create() could register the same file immediately
> > > after the mutex is released.
> > >
> > > Move htable_remove_proc_entry() back to mutex protection to
> > > fix this. And, fold htable_destroy() into htable_put() to make
> > > the code slightly easier to understand.
> >
> > Probably revert previous one?
> 
> The hung task could appear again if we move the cleanup
> back under mutex.

How could the hung task appear again by reverting
c4a3922d2d20c710f827? Please elaborate.

Thanks.

  reply	other threads:[~2020-02-18 22:05 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-13  6:53 [Patch nf] netfilter: xt_hashlimit: unregister proc file before releasing mutex Cong Wang
2020-02-18 21:35 ` Pablo Neira Ayuso
2020-02-18 21:40   ` Cong Wang
2020-02-18 22:05     ` Pablo Neira Ayuso [this message]
2020-02-20  3:32       ` Cong Wang
2020-02-26 18:11         ` Pablo Neira Ayuso
2020-02-26 19:14           ` Pablo Neira Ayuso

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