From: Greg KH <gregkh@linuxfoundation.org>
To: Siddh Raman Pant <code@siddh.me>
Cc: syzbot+c70d87ac1d001f29a058@syzkaller.appspotmail.com,
linux-kernel-mentees
<linux-kernel-mentees@lists.linuxfoundation.org>,
linux-security-modules <linux-security-module@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
David Howells <dhowells@redhat.com>,
Eric Dumazet <edumazet@google.com>,
Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
"Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Subject: Re: [PATCH] kernel/watch_queue: Make pipe NULL while clearing watch_queue
Date: Sat, 23 Jul 2022 16:04:17 +0200 [thread overview]
Message-ID: <Ytv/4Tljvlt0PJ2r@kroah.com> (raw)
In-Reply-To: <20220723135447.199557-1-code@siddh.me>
On Sat, Jul 23, 2022 at 07:24:47PM +0530, Siddh Raman Pant via Linux-kernel-mentees wrote:
> If not done, a reference to a freed pipe remains in the watch_queue,
> as this function is called before freeing a pipe in free_pipe_info()
> (see line 834 of fs/pipe.c).
>
> This causes a UAF when post_one_notification tries to access the pipe on
> a key update, which is reported by syzbot.
>
> Bug report: https://syzkaller.appspot.com/bug?id=1870dd7791ba05f2ea7f47f7cbdde701173973fc
> Reported-and-tested-by: syzbot+c70d87ac1d001f29a058@syzkaller.appspotmail.com
>
> Signed-off-by: Siddh Raman Pant <code@siddh.me>
> ---
> kernel/watch_queue.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c
> index bb9962b33f95..bab9e09c74cf 100644
> --- a/kernel/watch_queue.c
> +++ b/kernel/watch_queue.c
> @@ -637,8 +637,17 @@ void watch_queue_clear(struct watch_queue *wqueue)
> spin_lock_bh(&wqueue->lock);
> }
>
> - spin_unlock_bh(&wqueue->lock);
> rcu_read_unlock();
Also you now have a spinlock held when calling rcu_read_unlock(), are
you sure that's ok?
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next prev parent reply other threads:[~2022-07-23 14:04 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-23 13:54 [PATCH] kernel/watch_queue: Make pipe NULL while clearing watch_queue Siddh Raman Pant via Linux-kernel-mentees
2022-07-23 14:03 ` Greg KH
2022-07-23 14:29 ` Siddh Raman Pant via Linux-kernel-mentees
2022-07-24 3:45 ` Khalid Masum
2022-07-24 4:02 ` Siddh Raman Pant via Linux-kernel-mentees
2022-07-23 14:04 ` Greg KH [this message]
2022-07-23 14:29 ` Siddh Raman Pant via Linux-kernel-mentees
2022-07-27 14:46 ` David Howells
2022-07-27 16:20 ` Siddh Raman Pant via Linux-kernel-mentees
2022-07-31 18:11 ` Dipanjan Das
2022-07-31 18:46 ` Siddh Raman Pant via Linux-kernel-mentees
2022-08-01 8:47 ` Greg KH
2022-08-01 8:53 ` Siddh Raman Pant via Linux-kernel-mentees
2022-07-27 14:15 ` David Howells
2022-07-27 14:23 ` Siddh Raman Pant via Linux-kernel-mentees
[not found] <20220801121513.28E4B5204D1@webmail.sinamail.sina.com.cn>
2022-08-01 12:52 ` Siddh Raman Pant via Linux-kernel-mentees
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