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Date: Fri, 9 Oct 2026 02:07:35 +0200
From: Florian Westphal <fw@strlen.de>
To: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Zihan Xi <zihanx@nebusec.ai>, netfilter-devel@vger.kernel.org,
	coreteam@netfilter.org, phil@nwl.cc, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, davem@davemloft.net,
	edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
	horms@kernel.org
Subject: Re: [PATCH nf v3 1/1] netfilter: x_tables: avoid holding mutex over
 faultable user copies
Message-ID: <asgwR9LsGCEMolQX@strlen.de>
References: <cover.1789885804.git.zihanx@nebusec.ai>
 <f88fc502b17b4022105a99eea407525807ee573e.1789885804.git.zihanx@nebusec.ai>
 <asgtQ3E2LVWqfV8D@chamomile>
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In-Reply-To: <asgtQ3E2LVWqfV8D@chamomile>

Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > The ebtables GET paths use a separate ebt_mutex and are outside this
> > IPv4/IPv6/ARP series.
> 
> I keep spinning on this, and I am not sure this fix is the right thing
> to do. There is no single caller of this pagefault_disable/enable() mm
> subsystem function in the net folder.

See:

https://lore.kernel.org/all/CAL4Wiir+CBGE=hXxHEBkyk0Au9B6G3=AdHFd5botrC-FF5BM5w@mail.gmail.com/raw

Quote:
| We have many places where copy_{from,to}_user() runs while a mutex or
| a socket lock is held, and some of these locks are global.

So I would not spend too much time on this, especially not for the
xtables get/setsockopt APIs.