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From: Giuseppe Scrivano <gscrivan@redhat.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	alexander.deucher@amd.com, broonie@kernel.org,
	chris@chris-wilson.co.uk, David Miller <davem@davemloft.net>,
	deepa.kernel@gmail.com, Greg KH <gregkh@linuxfoundation.org>,
	luc.vanoostenryck@gmail.com, lucien xin <lucien.xin@gmail.com>,
	Ingo Molnar <mingo@kernel.org>,
	Neil Horman <nhorman@tuxdriver.com>,
	syzkaller-bugs@googlegroups.com,
	Vladislav Yasevich <vyasevich@gmail.com>
Subject: Re: [PATCH linux-next] mqueue: fix IPC namespace use-after-free
Date: Tue, 19 Dec 2017 19:40:43 +0100	[thread overview]
Message-ID: <87vah2ftn8.fsf@redhat.com> (raw)
In-Reply-To: <874lomhcwb.fsf@redhat.com> (Giuseppe Scrivano's message of "Tue, 19 Dec 2017 17:59:32 +0100")

Giuseppe Scrivano <gscrivan@redhat.com> writes:

> The only issue I've seen with my version is that if I do:
>
> # unshare -im /bin/sh
> # mount -t mqueue mqueue /dev/mqueue
> # touch /dev/mqueue/foo
> # umount /dev/mqueue
> # mount -t mqueue mqueue /dev/mqueue
>
> then /dev/mqueue/foo doesn't exist at this point.  Your patch does not
> have this problem and /dev/mqueue/foo is again accessible after the
> second mount.

although, how much is that of an issue?  Is there any other way to delay
the cost of kern_mount_data()?  Most containers have /dev/mqueue mounted
but it is not really going to be used.

Would it be possible somehow to postpone it until the first inode is
created?

Thanks,
Giuseppe

  reply	other threads:[~2017-12-19 18:40 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-19 10:14 Giuseppe Scrivano
2017-12-19 11:48 ` Al Viro
2017-12-19 15:32   ` Al Viro
2017-12-19 15:44     ` Al Viro
2017-12-19 16:31       ` Dmitry Vyukov
2017-12-19 17:02         ` Giuseppe Scrivano
2017-12-19 16:59     ` Giuseppe Scrivano
2017-12-19 18:40       ` Giuseppe Scrivano [this message]
2017-12-19 20:14         ` Al Viro
2017-12-19 21:49           ` Eric W. Biederman
2017-12-19 22:40             ` Al Viro
2017-12-19 23:36               ` Eric W. Biederman
2017-12-21 19:19           ` Giuseppe Scrivano

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