RE: [RFC] debugfs: protect against rmmod while files are open

[David Laight]

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?

	David

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