From: Greg KH <gregkh@linuxfoundation.org>
To: Tejun Heo <tj@kernel.org>
Cc: Yufen Yu <yuyufen@huawei.com>,
axboe@kernel.dk, linux-block@vger.kernel.org,
linux-fsdevel@vger.kernel.org, jack@suse.cz, bvanassche@acm.org,
tytso@mit.edu
Subject: Re: [PATCH v2 0/7] bdi: fix use-after-free for bdi device
Date: Wed, 4 Mar 2020 21:07:25 +0100 [thread overview]
Message-ID: <20200304200725.GB1906005@kroah.com> (raw)
In-Reply-To: <20200304185739.GN189690@mtj.thefacebook.com>
On Wed, Mar 04, 2020 at 01:57:39PM -0500, Tejun Heo wrote:
> Hey, Greg.
>
> On Wed, Mar 04, 2020 at 06:29:07PM +0100, Greg KH wrote:
> > How does that happen? Who has access to a kobject without also having
> > the reference count incremented at the same time? Is this through sysfs
> > or somewhere within the kernel itself?
>
> Hopefully, this part was addressed in the other reply.
Yes, thanks.
> > The struct device refcount should be all that is needed, don't use RCU
> > just to "delay freeing this object until some later time because someone
> > else might have a pointer to id". That's ripe for disaster.
>
> I think it's an idiomatic use of rcu given the circumstances. Whether
> the circumstances are reasonable is totally debatable.
They are not reasonable :)
next prev parent reply other threads:[~2020-03-04 20:07 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-26 11:18 [PATCH v2 0/7] bdi: fix use-after-free for bdi device Yufen Yu
2020-02-26 11:18 ` [PATCH v2 1/7] blk-wbt: use bdi_dev_name() to get device name Yufen Yu
2020-02-26 11:18 ` [PATCH v2 2/7] fs/ceph: " Yufen Yu
2020-02-26 11:18 ` [PATCH v2 3/7] bdi: protect device lifetime with RCU Yufen Yu
2020-03-04 17:05 ` Tejun Heo
2020-03-04 17:22 ` Greg Kroah-Hartman
2020-03-04 17:23 ` Greg Kroah-Hartman
2020-03-04 18:50 ` Tejun Heo
2020-03-04 19:10 ` Theodore Y. Ts'o
2020-03-04 19:15 ` Tejun Heo
2020-03-04 20:05 ` Greg Kroah-Hartman
2020-03-05 1:22 ` Tejun Heo
2020-03-06 16:25 ` Greg Kroah-Hartman
2020-03-07 9:13 ` Yufen Yu
2020-02-26 11:18 ` [PATCH v2 4/7] bdi: create a new function bdi_get_dev_name() Yufen Yu
2020-02-26 11:18 ` [PATCH v2 5/7] bfq: fix potential kernel crash when print dev err info Yufen Yu
2020-02-26 11:18 ` [PATCH v2 6/7] memcg: fix crash in wb_workfn when bdi unregister Yufen Yu
2020-02-26 11:18 ` [PATCH v2 7/7] blk-wbt: replace bdi_dev_name() with bdi_get_dev_name() Yufen Yu
2020-03-04 17:29 ` [PATCH v2 0/7] bdi: fix use-after-free for bdi device Greg KH
2020-03-04 18:57 ` Tejun Heo
2020-03-04 20:07 ` Greg KH [this message]
2020-03-04 19:02 ` Theodore Y. Ts'o
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