From: Andrew Morton <akpm@linux-foundation.org>
To: Aristeu Rozanski <aris@redhat.com>
Cc: linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>,
Li Zefan <lizefan@huawei.com>, James Morris <jmorris@namei.org>,
Pavel Emelyanov <xemul@openvz.org>,
Serge Hallyn <serge.hallyn@canonical.com>,
Jiri Slaby <jslaby@suse.cz>,
cgroups@vger.kernel.org
Subject: Re: [PATCH] device_cgroup: fix unchecked cgroup parent usage
Date: Wed, 31 Oct 2012 16:35:01 -0700 [thread overview]
Message-ID: <20121031163501.79a0950e.akpm@linux-foundation.org> (raw)
In-Reply-To: <20121031160430.GD14789@redhat.com>
On Wed, 31 Oct 2012 12:04:30 -0400
Aristeu Rozanski <aris@redhat.com> wrote:
> In 4cef7299b4786879a3e113e84084a72b24590c5b the cgroup parent usage is
> unchecked. root will not have a parent and trying to use
> device.{allow,deny} will cause problems.
>From my reading of the code "problems" means "kernel null pointer
dereference".
> For some reason my stressing
> scripts didn't test the root directory so I didn't catch it on my
> regular tests.
>
> --- github.orig/security/device_cgroup.c 2012-10-26 17:18:01.739366780 -0400
> +++ github/security/device_cgroup.c 2012-10-29 10:03:33.221918003 -0400
> @@ -352,6 +352,8 @@
> */
> static inline int may_allow_all(struct dev_cgroup *parent)
offtopic: this function could quite neatly have a bool return type.
> {
> + if (!parent)
> + return 1;
hm. Does it need a comment explaining what and why? I guess not... just.
> return parent->behavior == DEVCG_DEFAULT_ALLOW;
> }
next prev parent reply other threads:[~2012-10-31 23:35 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-31 16:04 [PATCH] device_cgroup: fix unchecked cgroup parent usage Aristeu Rozanski
2012-10-31 16:23 ` Tejun Heo
2012-10-31 17:21 ` Serge Hallyn
2012-10-31 23:35 ` Andrew Morton [this message]
2012-11-01 13:28 ` Aristeu Rozanski
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