linux-kernel - Re: [RFC PATCH] hidraw: protect hidraw

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Date:	Tue, 20 Sep 2011 15:25:44 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	James Hogan <james.hogan@...tec.com>
Cc:	David Herrmann <dh.herrmann@...glemail.com>,
	linux-input@...r.kernel.org,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] hidraw: protect hidraw_disconnect() better

On Tue, 20 Sep 2011, James Hogan wrote:

> >> Signed-off-by: James Hogan <james.hogan@...tec.com>
> >> ---
> >>  drivers/hid/hidraw.c |    4 ++--
> >>  1 files changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
> >> index c79578b..a8c2b7b 100644
> >> --- a/drivers/hid/hidraw.c
> >> +++ b/drivers/hid/hidraw.c
> >> @@ -510,13 +510,12 @@ void hidraw_disconnect(struct hid_device *hid)
> >>  {
> >>        struct hidraw *hidraw = hid->hidraw;
> >>
> >> +       mutex_lock(&minors_lock);
> >>        hidraw->exist = 0;
> >>
> >>        device_destroy(hidraw_class, MKDEV(hidraw_major, hidraw->minor));
> > 
> > This does not destroy any open file descriptor and we haven't
> > registered any kind of hook so hidraw_destroy() will not be called
> > here.
> > This seems safe to me.
> > We also do not check for hidraw->exist on *_open() callback so
> > including this in the critical section seems fine.
> 
> That's good then. Thanks for checking it.
> 
> > 
> >> -       mutex_lock(&minors_lock);
> >>        hidraw_table[hidraw->minor] = NULL;
> >> -       mutex_unlock(&minors_lock);
> >>
> >>        if (hidraw->open) {
> >>                hid_hw_close(hid);
> >> @@ -524,6 +523,7 @@ void hidraw_disconnect(struct hid_device *hid)
> >>        } else {
> >>                kfree(hidraw);
> >>        }
> >> +       mutex_unlock(&minors_lock);
> >>  }
> >>  EXPORT_SYMBOL_GPL(hidraw_disconnect);
> >>
> >> --
> >> 1.7.2.3
> > 
> > Nice catch. I've tested it on linux-next tree and I can confirm the
> > bug. The fix seems ok to me.

Good, thanks. I have now applied it with your Tested-by:, please shout if 
you don't want that.

> Shall I resend without RFC? I'll add Cc: <stable@...nel.org> too if
> there aren't objections.

stable@...nel.org wouldn't work anyway due to kernel.org being down ...

-- 
Jiri Kosina
SUSE Labs
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