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Date: Mon, 9 Jun 2014 14:29:56 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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        Andrew Morton <akpm@linux-foundation.org>,
        Ingo Molnar <mingo@kernel.org>, Clark Williams <williams@redhat.com>
Subject: Re: safety of *mutex_unlock() (Was: [BUG] signal: sighand
 unprotected when accessed by /proc)
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On Mon, 9 Jun 2014 20:15:53 +0200
Oleg Nesterov <oleg@redhat.com> wrote:


> > That would indeed be a bad thing, as it could potentially lead to
> > use-after-free bugs.  Though one could argue that any code that resulted
> > in use-after-free would be quite aggressive.  But still...
> 
> And once again, note that the normal mutex is already unsafe (unless I missed
> something).

Is it unsafe?

This thread was started because of a bug we triggered in -rt, which
ended up being a change specific to -rt that modified the way slub
handled SLAB_DESTROY_BY_RCU. What else was wrong with it?

-- Steve