From: Al Viro <viro@ZenIV.linux.org.uk>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Dave Jones <davej@redhat.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: weird use-after-free bug in module_put
Date: Fri, 19 Oct 2012 18:09:51 +0100 [thread overview]
Message-ID: <20121019170951.GM2616@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20121019163318.GA2152@core.coreip.homeip.net>
On Fri, Oct 19, 2012 at 09:33:18AM -0700, Dmitry Torokhov wrote:
> We are now removing instance of character device corresponding to input
> device when input device disappears.
>
> Ah, I know... cdev is embedded in evdev, but lives longer.. I do want to
> keep cdev embedded as it allows me to easily get to evdev in
> evdev_open(), but I need to be able to add and then drop reference to
> evdev from cdev's ->release() method. This means I need to override it.
>
> Or I could have cdev separately allocated, but then I'd like to have a
> void pointer in "struct cdev" so I could get from it back to
> corresponding evdev.
Your real problem is that you have two kobjects embedded into the same
thing. It can work, but you need to make the secondary (one that does
*not* free in its ->release()) pin the primary. Sigh... Device model
sucks, film at 11...
next prev parent reply other threads:[~2012-10-19 17:09 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-19 14:43 Dave Jones
2012-10-19 15:34 ` Dave Jones
2012-10-19 16:33 ` Dmitry Torokhov
2012-10-19 17:09 ` Al Viro [this message]
2012-10-19 17:36 ` Dmitry Torokhov
2012-10-19 17:50 ` Al Viro
2012-10-19 18:12 ` Dmitry Torokhov
2012-10-21 7:24 ` [PATCH 1/2] char_dev: allow setting up and pinning parent devices Dmitry Torokhov
2012-10-21 7:24 ` [PATCH 2/2] Input: fix use-after-free introduced with dynamic minor changes Dmitry Torokhov
2012-10-21 7:39 ` [PATCH 1/2] char_dev: allow setting up and pinning parent devices Al Viro
2012-10-21 8:13 ` Dmitry Torokhov
2012-10-22 0:57 ` [PATCH 1/2] char_dev: pin parent kobject Dmitry Torokhov
2012-10-22 0:57 ` [PATCH 2/2] Input: fix use-after-free introduced with dynamic minor changes Dmitry Torokhov
2012-10-22 5:02 ` [PATCH 1/2] char_dev: pin parent kobject Linus Torvalds
2012-10-22 5:42 ` Al Viro
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