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From: Pavel Begunkov <asml.silence@gmail.com>
To: Bernd Schubert <bernd@bsbernd.com>,
	Bernd Schubert <bschubert@ddn.com>, Berkant Koc <me@berkoc.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	Miklos Szeredi <miklos@szeredi.hu>
Cc: "security@kernel.org" <security@kernel.org>,
	Joanne Koong <joannelkoong@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"io-uring@vger.kernel.org" <io-uring@vger.kernel.org>,
	Jens Axboe <axboe@kernel.dk>,
	fuse-devel <fuse-devel@lists.linux.dev>
Subject: Re: [PATCH 2/2] fuse: wait for aborted connection before releasing last fuse_dev
Date: Mon, 18 May 2026 11:32:16 +0100	[thread overview]
Message-ID: <edcff681-bb4f-491d-b87b-eab5919d0623@gmail.com> (raw)
In-Reply-To: <a44344bb-ad71-41f5-a3c5-81eb99442e5e@bsbernd.com>

On 5/18/26 10:50, Bernd Schubert wrote:

>>>> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
>>>> index 5dda7080f4a9..7d9c06654a98 100644
>>>> --- a/fs/fuse/dev.c
>>>> +++ b/fs/fuse/dev.c
>>>> @@ -2566,6 +2566,7 @@ int fuse_dev_release(struct inode *inode, struct file *file)
>>>>                   if (last) {
>>>>                           WARN_ON(fc->iq.fasync != NULL);
>>>>                           fuse_abort_conn(fc);
>>>> +                       fuse_wait_aborted(fc);
>>>>                   }
>>>>                   fuse_conn_put(fc);
>>>>           }
>>>
>>> I might be wrong, but I don't think it is possible, Maybe Pavel or Jens
>>> could help (added to CC). Basically as long as
>>> fuse_uring_async_stop_queues() runs we do not have completed all
>>> io-uring commands via io_uring_cmd_done() and as long as we do not have
>>> completed these io-uring commands.
>>
>> If I understand the question right, yes, fuse io_uring cmd requests hold
>> a reference to the fuse file, so until you complete them the file will
>> not get released.
> 
> 
> Sorry, had totally messed up the phrase, can't read it myself.
> 
> What I mean is that the io-uring was set up with /dev/fuse as file and
> as long as fuse holds non-completed 'struct io_uring_cmd *cmd' objects
> there is a reference on the /dev/fuse fd, which blocks the call of
> fuse_dev_release().

Yep, that's right

-- 
Pavel Begunkov


  reply	other threads:[~2026-05-18 10:32 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20260517095846.fuse-iouring-uaf.dc5f5dbb71dc@berkoc.com>
     [not found] ` <2026051703-equinox-multitude-91e2@gregkh>
2026-05-17 12:59   ` [PATCH 0/2] fuse: io-uring: fix two UAFs in dev_uring.c teardown Berkant Koc
2026-05-17 12:59     ` [PATCH 1/2] fuse: io-uring: clear ent->fuse_req in commit_fetch error path Berkant Koc
2026-05-17 14:11       ` Bernd Schubert
2026-05-17 14:24         ` Berkant Koc
2026-05-17 12:59     ` [PATCH 2/2] fuse: wait for aborted connection before releasing last fuse_dev Berkant Koc
2026-05-17 15:00       ` Bernd Schubert
2026-05-18  1:13         ` Berkant Koc
2026-05-18  9:55           ` Bernd Schubert
2026-05-18 11:47             ` Bernd Schubert
2026-05-18 14:32               ` Berkant Koc
2026-05-18 14:46                 ` Bernd Schubert
2026-05-18 15:35                   ` Joanne Koong
2026-05-18 17:49                     ` Berkant Koc
2026-05-18 15:47                   ` Berkant Koc
2026-05-18  9:06         ` Pavel Begunkov
2026-05-18  9:50           ` Bernd Schubert
2026-05-18 10:32             ` Pavel Begunkov [this message]
2026-05-17 13:14     ` [PATCH 0/2] fuse: io-uring: fix two UAFs in dev_uring.c teardown Berkant Koc
2026-05-17 13:43       ` Bernd Schubert
2026-05-17 14:02         ` Berkant Koc

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