From: Al Viro <viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
To: Paul Menage <menage-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: Linux Containers
<containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>,
Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH] cgroups: fix possible use after free
Date: Tue, 10 Feb 2009 12:45:27 +0000 [thread overview]
Message-ID: <20090210124527.GA28946@ZenIV.linux.org.uk> (raw)
In-Reply-To: <6599ad830902100215o185edd31k8731e033717dbb49-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On Tue, Feb 10, 2009 at 02:15:36AM -0800, Paul Menage wrote:
> On Tue, Feb 10, 2009 at 1:31 AM, Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org> wrote:
> > In cgroup_kill_sb(), root is freed before sb is detached from the list,
> > so another sget() may find this sb and call cgroup_test_super(),
> > which will access the root that has been freed.
>
> I think that I'd assumed that by the time we get to cgroup_kill_sb()
> there's no chance of the sb being resurrected by sget().
There is none. grab_super() will fail to get it, so sget() will go
through retry logics. Which doesn't mean that test won't be called
on it in the meanwhile.
WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux Containers <containers@lists.linux-foundation.org>
Subject: Re: [PATCH] cgroups: fix possible use after free
Date: Tue, 10 Feb 2009 12:45:27 +0000 [thread overview]
Message-ID: <20090210124527.GA28946@ZenIV.linux.org.uk> (raw)
In-Reply-To: <6599ad830902100215o185edd31k8731e033717dbb49@mail.gmail.com>
On Tue, Feb 10, 2009 at 02:15:36AM -0800, Paul Menage wrote:
> On Tue, Feb 10, 2009 at 1:31 AM, Li Zefan <lizf@cn.fujitsu.com> wrote:
> > In cgroup_kill_sb(), root is freed before sb is detached from the list,
> > so another sget() may find this sb and call cgroup_test_super(),
> > which will access the root that has been freed.
>
> I think that I'd assumed that by the time we get to cgroup_kill_sb()
> there's no chance of the sb being resurrected by sget().
There is none. grab_super() will fail to get it, so sget() will go
through retry logics. Which doesn't mean that test won't be called
on it in the meanwhile.
next prev parent reply other threads:[~2009-02-10 12:45 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-10 9:31 [PATCH] cgroups: fix possible use after free Li Zefan
2009-02-10 10:15 ` Paul Menage
[not found] ` <6599ad830902100215o185edd31k8731e033717dbb49-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2009-02-10 12:45 ` Al Viro [this message]
2009-02-10 12:45 ` Al Viro
[not found] ` <20090210124527.GA28946-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2009-02-11 0:01 ` Paul Menage
2009-02-11 0:01 ` Paul Menage
[not found] ` <6599ad830902101601i294ffaa5xd01611c5121a5685-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2009-02-11 1:19 ` Al Viro
2009-02-11 1:19 ` Al Viro
2009-02-11 1:54 ` Paul Menage
[not found] ` <20090211011933.GB28946-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2009-02-11 1:54 ` Paul Menage
[not found] ` <4991497B.4030200-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2009-02-10 10:15 ` Paul Menage
2009-02-11 0:01 ` Paul Menage
2009-02-11 0:01 ` Paul Menage
-- strict thread matches above, loose matches on Subject: below --
2009-02-10 9:31 Li Zefan
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