Message-ID: <1415946985.3398.125.camel@decadent.org.uk>
Subject: Re: [PATCH 3.16.y-ckt 009/170] NFS: Fix /proc/fs/nfsfs/servers and
 /proc/fs/nfsfs/volumes
From: Ben Hutchings <ben@decadent.org.uk>
To: Luis Henriques <luis.henriques@canonical.com>
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        kernel-team@lists.ubuntu.com,
        Trond Myklebust <trond.myklebust@primarydata.com>,
        Stanislav Kinsbursky <skinsbursky@parallels.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>
Date: Fri, 14 Nov 2014 06:36:25 +0000
In-Reply-To: <1415704129-12709-10-git-send-email-luis.henriques@canonical.com>
References: <1415704129-12709-1-git-send-email-luis.henriques@canonical.com>
	 <1415704129-12709-10-git-send-email-luis.henriques@canonical.com>
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On Tue, 2014-11-11 at 11:06 +0000, Luis Henriques wrote:
> 3.16.7-ckt1 -stable review patch.  If anyone has any objections, please l=
et me know.
>=20
> ------------------
>=20
> From: "Eric W. Biederman" <ebiederm@xmission.com>
>=20
> commit 65b38851a17472d31fec9019fc3a55b0802dab88 upstream.
>=20
> The usage of pid_ns->child_reaper->nsproxy->net_ns in
> nfs_server_list_open and nfs_client_list_open is not safe.
>=20
> /proc for a pid namespace can remain mounted after the all of the
> process in that pid namespace have exited.  There are also times
> before the initial process in a pid namespace has started or after the
> initial process in a pid namespace has exited where
> pid_ns->child_reaper can be NULL or stale.  Making the idiom
> pid_ns->child_reaper->nsproxy a double whammy of problems.
>=20
> Luckily all that needs to happen is to move /proc/fs/nfsfs/servers and
> /proc/fs/nfsfs/volumes under /proc/net to /proc/net/nfsfs/servers and
> /proc/net/nfsfs/volumes and add a symlink from the original location,
> and to use seq_open_net as it has been designed.
>=20
> Cc: Trond Myklebust <trond.myklebust@primarydata.com>
> Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
[...]

This needs a follow-up:

commit 21e81002f9788a3af591416b6dec60d7b67f2fb2
Author: Cong Wang <xiyou.wangcong@gmail.com>
Date:   Mon Sep 8 16:17:55 2014 -0700

    nfs: fix kernel warning when removing proc entry

Ben.

--=20
Ben Hutchings
Never put off till tomorrow what you can avoid all together.

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