From: Christoph Hellwig <hch@infradead.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Markus Pargmann <mpa@pengutronix.de>, Tejun Heo <tj@kernel.org>,
nbd-general@lists.sourceforge.net, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] kthread: introduce kthread_get_run() to fix __nbd_ioctl()
Date: Mon, 26 Oct 2015 17:26:42 -0700 [thread overview]
Message-ID: <20151027002642.GA32444@infradead.org> (raw)
In-Reply-To: <20151025142713.GA30965@redhat.com>
On Sun, Oct 25, 2015 at 03:27:13PM +0100, Oleg Nesterov wrote:
> It is not safe to use the task_struct returned by kthread_run(threadfn)
> if threadfn() can exit before the "owner" does kthread_stop(), nothing
> protects this task_struct.
>
> So __nbd_ioctl() looks buggy; a killed nbd_thread_send() can exit, free
> its task_struct, and then kthread_stop() can use the freed/reused memory.
>
> Add the new trivial helper, kthread_get_run(). Hopefully it will have more
> users, this patch changes __nbd_ioctl() as an example.
This looks horrible. I think the real problem is that nbd is totally
abusing signals for kthreads and that needs to go away.
next prev parent reply other threads:[~2015-10-27 0:26 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-25 14:26 [PATCH 0/1] kthread: introduce kthread_get_run() to fix __nbd_ioctl() Oleg Nesterov
2015-10-25 14:27 ` [PATCH 1/1] " Oleg Nesterov
2015-10-26 7:33 ` Markus Pargmann
2015-10-28 15:27 ` Oleg Nesterov
2015-10-27 0:26 ` Christoph Hellwig [this message]
2015-10-27 7:03 ` Markus Pargmann
2015-10-28 15:37 ` Oleg Nesterov
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