Re: get_device_parent() race bug

From: Tejun Heo
Date: Mon Oct 05 2009 - 21:16:54 EST


Greg KH wrote:
>>> BUG: unable to handle kernel NULL pointer dereference at 0000000000000038
>> Ping. This one needs to be fixed in -stable. It can be triggered by
>> other char devices too.
>
> Sorry, been slowly catching up...
>
> This can be triggered by char devices? Huh? How? I don't see the
> failure path that is happening here.

Oooh, s/char/virtual/. The bug is in the path which creates a
directory under the phony parent.

> And char devices shouldn't really be using the kobject at all, except
> for a very basic reference count.
>
> I keep threatening to rip kobject out of a char device and just use a
> kref, as that is all that is really needed. Well, that and the kmap
> stuff, but again, it's not a "real" kobject being used there...
>
> Perhaps now is the time to do this.

Yay!

--
tejun
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