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From: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
To: David Laight <David.Laight@aculab.com>
Cc: 'Johannes Berg' <johannes@sipsolutions.net>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"nstange@suse.de" <nstange@suse.de>,
	"ap420073@gmail.com" <ap420073@gmail.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
	"rafael@kernel.org" <rafael@kernel.org>
Subject: Re: [RFC] debugfs: protect against rmmod while files are open
Date: Fri, 9 Oct 2020 13:15:17 +0200	[thread overview]
Message-ID: <20201009111517.GA508813@kroah.com> (raw)
In-Reply-To: <8fe62082d9774a1fb21894c27e140318@AcuMS.aculab.com>

On Fri, Oct 09, 2020 at 10:56:16AM +0000, David Laight wrote:
> From: Johannes Berg
> > Sent: 09 October 2020 11:48
> > 
> > On Fri, 2020-10-09 at 12:41 +0200, Johannes Berg wrote:
> > 
> > > If the fops doesn't have a release method, we don't even need
> > > to keep a reference to the real_fops, we can just fops_put()
> > > them already in debugfs remove, and a later full_proxy_release()
> > > won't call anything anyway - this just crashed/UAFed because it
> > > used real_fops, not because there was actually a (now invalid)
> > > release() method.
> > 
> > I actually implemented something a bit better than what I described - we
> > never need a reference to the real_fops for the release method alone,
> > and that means if the release method is in the kernel image, rather than
> > a module, it can still be called.
> > 
> > That together should reduce the ~117 places you changed in the large
> > patchset to around a handful.
> 
> Is there an equivalent problem for normal cdev opens
> in any modules?

What does cdev have to do with debugfs?

  parent reply	other threads:[~2020-10-09 11:14 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-08 15:48 [PATCH net 000/117] net: avoid to remove module when its debugfs is being used Taehee Yoo
2020-10-08 15:59 ` David Laight
2020-10-08 16:14   ` Johannes Berg
2020-10-08 16:37     ` Taehee Yoo
2020-10-09  5:38       ` Nicolai Stange
2020-10-09 10:07         ` Taehee Yoo
2020-10-09  5:09     ` Nicolai Stange
2020-10-09  7:45       ` Johannes Berg
2020-10-09 10:15         ` Taehee Yoo
2020-10-09 10:21           ` Johannes Berg
2020-10-09 10:41             ` [RFC] debugfs: protect against rmmod while files are open Johannes Berg
2020-10-09 10:48               ` Johannes Berg
2020-10-09 10:56                 ` David Laight
2020-10-09 10:56                   ` Johannes Berg
2020-10-09 11:15                   ` gregkh [this message]
2020-10-09 15:33             ` [PATCH net 000/117] net: avoid to remove module when its debugfs is being used Steve deRosier
2020-10-09  7:53       ` [CRAZY-RFF] debugfs: track open files and release on remove Johannes Berg
2020-10-09  8:03         ` Greg KH
2020-10-09  8:06           ` Johannes Berg
2020-10-09  8:16             ` Greg KH
2020-10-09  8:19               ` Johannes Berg
2020-10-09  8:34                 ` David Laight
2020-10-09  8:44                   ` Johannes Berg
2020-10-09  9:00                     ` David Laight
2020-10-09  8:47                 ` Greg KH
2020-10-09  8:48                   ` Johannes Berg
2020-10-10  9:38                     ` Greg KH
2020-10-10 10:47                       ` Johannes Berg

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