Received-SPF: pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Chuck Lever III <chuck.lever@oracle.com>
To:     Bruce Fields <bfields@fieldses.org>,
        "Ho, Patrick" <Patrick.Ho@netapp.com>
CC:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH] nfsd: fix error handling of register_pernet_subsys() in
 init_nfsd()
Thread-Topic: [PATCH] nfsd: fix error handling of register_pernet_subsys() in
 init_nfsd()
Thread-Index: Ade1jt37NNfgpkRySiiZJ5n/Oif8NgAdt90AAAHJKgA=
Date:   Thu, 30 Sep 2021 15:07:28 +0000
Message-ID: <F04E6E6F-E01F-4F0B-9F62-A3579BA0EF89@oracle.com>
References: <SJ0PR06MB8327D188504E0F367C8B4E53F4AA9@SJ0PR06MB8327.namprd06.prod.outlook.com>
 <20210930141620.GA9422@fieldses.org>
In-Reply-To: <20210930141620.GA9422@fieldses.org>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?ZhZvW2yUkc3YWs61ljAYJJpgiAvr6/SPYAazJT+Bpg0K1kx4nte7JaHXUASG?=
 =?us-ascii?Q?++Vu9t4f2QyFsg2IvafzNFPE6MCtbYj/tBhYfeA8BwK+FsAN3ARkCGIJ1bkZ?=
 =?us-ascii?Q?logqq5aBstprGLdIFw4OmSzBRViKsUJC1+bFTLFQfgbQJIDwz1Mp9plqUp6w?=
 =?us-ascii?Q?YyHwh6YkSKGHfbIjXKG1t/Mi+Dst7I3UIpqgc3HwYHxBuNxBKQaikVsXa/0s?=
 =?us-ascii?Q?D2lj5DeKC4d8tDRbzi/OArwf2WHhCqMZBfSaP0v5kva/7UZbFkWPLsT2UX9P?=
 =?us-ascii?Q?fAB5Ael+QBubQLMAns+7aTd0vjPJvdNDsUmaJ4RfpE2pU61qxGa04wGx0OMI?=
 =?us-ascii?Q?hb/6k5o2OEmVRXVE2nXhHY+osrcK6gg3JNHSqX7Z5uWTNIECEVM/iOFKdPlf?=
 =?us-ascii?Q?31IwYaI+HrCsPNPSJ/2bdg8uKWY4t3NmMOik8YuVEiIYIHRlsuzLciYAfd5s?=
 =?us-ascii?Q?Br0UCHeah1rrTjJyPV4emdJpUChQGnaCBKbxaa6kxsEuk2khVQzXpVY2Rri5?=
 =?us-ascii?Q?xZ4oLyG1CfNyPL9cylGuQHbGWFEZ6jD8s2K6W7QaCYBW4Y92iPJ3MO7NuUUV?=
 =?us-ascii?Q?xDXe69tMiA900u0/fKQRYcr8UIh6Lpjl35vNKhBrjl6lLhC/QXtXbwtPdQF7?=
 =?us-ascii?Q?WUFBXRIokrP1Qa9WKci4K1xU4NV5J0/8x/TOVz6wUXg37zXy1D0th4vd6pP5?=
 =?us-ascii?Q?C/59/e6BkIa8Ep/nbvhpd22IkFy3oDJj62QDox7DupGea7JZaDsxbTZa54oj?=
 =?us-ascii?Q?5dy82QpqNkUz6+19zgdcfGYvlFnYPkyYQdAB59o7knD8heyd9GLqlpdFtzJT?=
 =?us-ascii?Q?JcihmVR1kuihpYuuE09tC6HxOxfJZbaO7oNgO3XmSLZiLg4LBwdOMuEd4UJa?=
 =?us-ascii?Q?FSW4ab3dpPju9B+hcGWIuHzL4PUEBNMuKQa02QgPkjWRti7p+wsvcY/1Bl9V?=
 =?us-ascii?Q?pMtdHKRbrY4Pz6VINsIIlHjYuHOpKQl19zYq8J0z/OQ2BSat5DGybneUuwbP?=
 =?us-ascii?Q?HYcpO0j081Aea6lisZ1fEnJKW0RekG53YFUu0gjXaYgpb9KVVRSKKkI7DYb5?=
 =?us-ascii?Q?0890WXxU7A9B89gCEI1YdASqaJKedwsMkmvsHabogh+5pw3Om31tqlG7W3w3?=
 =?us-ascii?Q?c4YhnLiZq6zFGlA7MkXZGzM5DzLu8ost7bN2buRrq0n1iJ2LObhPQr9dgF0T?=
 =?us-ascii?Q?6ehP81RoxLQXQVCzGiGOa38QNSUKmeisdqhzs07iohlXHh9OS5TwqCQnJ5BJ?=
 =?us-ascii?Q?GRK5eFq5geMxeLGWt9jgzsat4y2PKtWJYI2QiufdX3Kvm9aY1ZIitAKjQrzL?=
 =?us-ascii?Q?1ERppOP4eU2h20sMUBKJFrpC?=
x-ms-exchange-transport-forked: True
Content-Type: text/plain; charset="us-ascii"
Content-ID: <7A1947EB6AA2DF4894A2B026633DAC95@namprd10.prod.outlook.com>
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: SJ0PR10MB4688.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 13de9415-5b92-4820-cfaf-08d9842404f2
X-MS-Exchange-CrossTenant-originalarrivaltime: 30 Sep 2021 15:07:28.5978
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: 00rsSWatXHGbbT7FODedayc4zu1qBe3/ZVHD7c/+BU+DQ3gwq7tB1Y3jiL9dUpzohOLjmovMGR0LnP4TRlJnwA==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR10MB3605
X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10123 signatures=668683
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 suspectscore=0 spamscore=0
 adultscore=0 bulkscore=0 mlxscore=0 malwarescore=0 mlxlogscore=999
 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2109230001
 definitions=main-2109300093
X-Proofpoint-GUID: uGfIxQOG0zV_BaRkALie_CBlTAjGr478
X-Proofpoint-ORIG-GUID: uGfIxQOG0zV_BaRkALie_CBlTAjGr478
Precedence: bulk
List-ID: <linux-nfs.vger.kernel.org>
X-Mailing-List: linux-nfs@vger.kernel.org


> On Sep 30, 2021, at 10:16 AM, J. Bruce Fields <bfields@fieldses.org> wrot=
e:
>=20
> On Thu, Sep 30, 2021 at 03:48:42AM +0000, Ho, Patrick wrote:
>>> From 7417896fcc7aea645fa0b89f39fa55979251dca3 Mon Sep 17 00:00:00 2001
>> From: Patrick Ho <Patrick.Ho@netapp.com>
>> Date: Sat, 21 Aug 2021 02:56:26 -0400
>> Subject: [PATCH] nfsd: fix error handling of register_pernet_subsys() in
>> init_nfsd()
>>=20
>> init_nfsd() should not unregister pernet subsys if the register fails
>> but should instead unwind from the last successful operation which is
>> register_filesystem().
>>=20
>> Unregistering a failed register_pernet_subsys() call can result in
>> a kernel GPF as revealed by programmatically injecting an error in
>> register_pernet_subsys().
>>=20
>> Verified the fix handled failure gracefully with no lingering nfsd
>> entry in /proc/filesystems.  This change was introduced by the commit
>> bd5ae9288d64 ("nfsd: register pernet ops last, unregister first"),
>> the original error handling logic was correct.
>=20
> Whoops, thanks for catching this.  I assume Chuck will pick it up.

Applied to the for-next branch at

git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git


> Acked-by: J. Bruce Fields <bfields@redhat.com>
>=20
> --b.
>=20
>>=20
>> Fixes: bd5ae9288d64 ("nfsd: register pernet ops last, unregister first")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Patrick Ho <Patrick.Ho@netapp.com>
>> ---
>> fs/nfsd/nfsctl.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>=20
>> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
>> index c2c3d9077dc5..09ae1a0873d0 100644
>> --- a/fs/nfsd/nfsctl.c
>> +++ b/fs/nfsd/nfsctl.c
>> @@ -1545,7 +1545,7 @@ static int __init init_nfsd(void)
>> 		goto out_free_all;
>> 	return 0;
>> out_free_all:
>> -	unregister_pernet_subsys(&nfsd_net_ops);
>> +	unregister_filesystem(&nfsd_fs_type);
>> out_free_exports:
>> 	remove_proc_entry("fs/nfs/exports", NULL);
>> 	remove_proc_entry("fs/nfs", NULL);
>> --=20
>> 2.17.1

--
Chuck Lever