linux-kernel - Re: [PATCH] nbd: restrict sockets to TCP and UDP

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Message-ID: <20251118181623.GK1427@redhat.com>
Date: Tue, 18 Nov 2025 18:16:23 +0000
From: "Richard W.M. Jones" <rjones@...hat.com>
To: Pavel Machek <pavel@....cz>
Cc: Eric Dumazet <edumazet@...gle.com>, Josef Bacik <josef@...icpanda.com>,
	Jens Axboe <axboe@...nel.dk>,
	linux-kernel <linux-kernel@...r.kernel.org>, netdev@...r.kernel.org,
	Eric Dumazet <eric.dumazet@...il.com>,
	syzbot+e1cd6bd8493060bd701d@...kaller.appspotmail.com,
	Mike Christie <mchristi@...hat.com>,
	Yu Kuai <yukuai1@...weicloud.com>, linux-block@...r.kernel.org,
	nbd@...er.debian.org
Subject: Re: [PATCH] nbd: restrict sockets to TCP and UDP

On Tue, Nov 18, 2025 at 06:56:33PM +0100, Pavel Machek wrote:
> Hi!
> 
> > Recently, syzbot started to abuse NBD with all kinds of sockets.
> > 
> > Commit cf1b2326b734 ("nbd: verify socket is supported during setup")
> > made sure the socket supported a shutdown() method.
> > 
> > Explicitely accept TCP and UNIX stream sockets.
> 
> Note that running nbd server and client on same machine is not safe in
> read-write mode. It may deadlock under low memory conditions.
> 
> Thus I'm not sure if we should accept UNIX sockets.

Both nbd-client and nbdkit have modes where they can mlock themselves
into RAM.

Rich.

-- 
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