Received-SPF: pass (google.com: domain of linux-ext4-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Catherine Hoang <catherine.hoang@oracle.com>
To:     "Darrick J. Wong" <djwong@kernel.org>
CC:     "tytso@mit.edu" <tytso@mit.edu>,
        "linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>
Subject: Re: [PATCH 2/2] ext4: don't fail GETFSUUID when the caller provides a
 long buffer
Thread-Topic: [PATCH 2/2] ext4: don't fail GETFSUUID when the caller provides
 a long buffer
Thread-Index: AQHY9WrHChlRScWowEiw9BRQJ/ICWw==
Date:   Fri, 11 Nov 2022 01:13:17 +0000
Message-ID: <A4F1A09D-AD40-4572-AA33-FF0ED0A3AC73@oracle.com>
References: <166811138334.327006.2601737065307668866.stgit@magnolia>
 <166811139478.327006.13879198441587445544.stgit@magnolia>
In-Reply-To: <166811139478.327006.13879198441587445544.stgit@magnolia>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?AVRlYLg6BSQ2jWyeRhN8qHgOzrSTuLKuwKWji+nCXl7gZyZQb0gI2hkOiV8Q?=
 =?us-ascii?Q?C/DxBGrj/n7vQMftSAj+vUUmR/yB17wQqxxfP86pdnUAy/Ds05kp/+O/tARv?=
 =?us-ascii?Q?UCGB8xozrmOn78jdGyDBgbWKH5yQR70f8op/v2nYELulgpjVPN75Rl3vnzBO?=
 =?us-ascii?Q?YYYTG8cUyFVXouCHzW9SlugzRApVIu3aMCjeXUq1J0Ez0nehhDduvGPWeLfB?=
 =?us-ascii?Q?vLk8mdEgfWiPSAzGEy5MN306QVabSFo4TAbmgX/DRjiOvFTZCsYwpVFfFTDh?=
 =?us-ascii?Q?Pi/34dCf8NPfWvNRmNUbSQFgesW0anQDNiQkAnX/fcB4ZLZNjWoh8sg+brDv?=
 =?us-ascii?Q?FzCoNidL/uFm4OI7La/tGdbeqQ6h8A3LvH61z2e3JtoFb+2NdVEiSfLNddMS?=
 =?us-ascii?Q?PlqN1eWaLwkYpRidqfb+z2uSWwXTxBAjMsrdMi+ZbnXH5ag14ysKyp5y4ez7?=
 =?us-ascii?Q?UjFx926Zz86kUZMyMAlLGfOEkfJJWeuEnP+k6P11gNvoeVyb80y6TpWLQuHE?=
 =?us-ascii?Q?KOMG6ESzSfWWeufM2A/0cTdQXhQ3oCGzRI+VGAPTdAgDGVN+zNMsVOpjQgEj?=
 =?us-ascii?Q?FV9d10vdPWdjYZVf74wDA+zbUlxi13YEKcJtAzL2s29LfJ8spCNZUZWepgMe?=
 =?us-ascii?Q?qVfd0y1O0bZvHMFZ2IPr0ky3fWhfa0DDckUVFygfMZY3exZZqbqfUUisf1x2?=
 =?us-ascii?Q?xxwRPohN52TqNpNNku4HaNOsuOmUy5ayknJ7g01/oOQv50V9e1Mnn3zhK7qO?=
 =?us-ascii?Q?W6/SUKi1xHaJ8KOl/Z2lXzt3oFPEJbZ2ieEam8e1pnvyrcAyhECyPbAqvSjn?=
 =?us-ascii?Q?3PcDQVN1SI7Gfp7d76IAqbHdYFkn078Us/o8YGVTGqhxytvBNjOawoWnuNKA?=
 =?us-ascii?Q?Vqn2rUHk5uTh/4SkDeITLVN92EscthjhHBbAcRgHUERxLzpkiYcnY5VTkq0S?=
 =?us-ascii?Q?4Oi4cqdPn8OKnEsfU8+NBfR3Yn3l4Pi4m2sf3MkwLLOqzdtFEymjtVZGiwas?=
 =?us-ascii?Q?xlXyG5HMIhekx8mHPfm8TlV7GT6o9gPraBcaxxG3J/7nJeHMSb/a55XckDcM?=
 =?us-ascii?Q?QQffj69/7pUYmSEvvRa/+FUu2X0TZ6sqLvNzdFFMfCQM/yifK0RVDyN87+FT?=
 =?us-ascii?Q?wNbcZOsQYLCBYRqGP3r33kptTTNVlzayprgZ65kWUMYQ0CmrxZ6kqEQNdiWg?=
 =?us-ascii?Q?k6zYEAswXZSZxsAskKyu4WT0klhEp2mfeeOEFcwuxEDameAFTpYyJKhgSsll?=
 =?us-ascii?Q?/zNh5VfBPEy2f7kU5vfj9BdyyH6ZS0A/KrrcjnIipgFlX39OQcxKMgn7hkaO?=
 =?us-ascii?Q?k9h3ZytVblEhSxaqz6NXSe2Tj54rOuO7DxqXtD5FHDLY/Rtrfj4I185jU/L4?=
 =?us-ascii?Q?4LJnE+y6w+Zd2dPSvYsHc150sWSLu4VSJJOvDoGEWQCHR9/uZnU/TTcrGlw+?=
 =?us-ascii?Q?Snv77tairEcsz1pFIqk9bOnwcGMuI2eC04twoXliXTdvOmaWVesTNd7O0UI6?=
 =?us-ascii?Q?lljMpAVHF/oxJgsv88bG58B+Sp+Ia1CzspzvaOMQwv6icSogvCFwCEc/UGVP?=
 =?us-ascii?Q?+dkG4Ecfhh0GA40fKQJ9aHkFb6EBXa5chJTlPPQw1AmvPA6NBUE+0GPotLno?=
 =?us-ascii?Q?XP5SVeIWSHDQUQMpXMGECK4mr4CTu+k47Sq6qjeur8tMyKaP/6cd/tm5gkaM?=
 =?us-ascii?Q?Fh7dRCr1iGbHUB6QGr7Gxx8O9JQ=3D?=
Content-Type: text/plain; charset="us-ascii"
Content-ID: <14A2531C157B4042BE8347E816692E2F@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: BLAPR10MB5316.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: ab767280-7540-4e03-52b5-08dac381ea44
X-MS-Exchange-CrossTenant-originalarrivaltime: 11 Nov 2022 01:13:17.4409
 (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: 4dZbtWgu7CW63YVM9LJ6t8RXhRIrxJE6oneNPV1yNvuzcQ3R9JE8/fibwnfSLm/m0UPFCFHAlDb5qQJWh7I7MmwJA0krbdRz0siz1CvIrEA=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR10MB5709
X-Proofpoint-Virus-Version: vendor=baseguard
 engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1
 definitions=2022-11-10_14,2022-11-09_01,2022-06-22_01
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 mlxscore=0 spamscore=0
 bulkscore=0 suspectscore=0 adultscore=0 malwarescore=0 mlxlogscore=999
 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2210170000
 definitions=main-2211110007
X-Proofpoint-ORIG-GUID: YIRoaFE0vGHfASBEEIbxRIa1HRcgmLx2
X-Proofpoint-GUID: YIRoaFE0vGHfASBEEIbxRIa1HRcgmLx2
X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,
        RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE autolearn=ham
        autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-ext4.vger.kernel.org>
X-Mailing-List: linux-ext4@vger.kernel.org

> On Nov 10, 2022, at 12:16 PM, Darrick J. Wong <djwong@kernel.org> wrote:
>=20
> From: Darrick J. Wong <djwong@kernel.org>
>=20
> If userspace provides a longer UUID buffer than is required, we
> shouldn't fail the call with EINVAL -- rather, we can fill the caller's
> buffer with the bytes we /can/ fill, and update the length field to
> reflect what we copied.  This doesn't break the UAPI since we're
> enabling a case that currently fails, and so far Ted hasn't released a
> version of e2fsprogs that uses the new ext4 ioctl.
>=20
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Looks good
Reviewed-by: Catherine Hoang <catherine.hoang@oracle.com>
> ---
> fs/ext4/ioctl.c |    6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>=20
>=20
> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> index 5f91f3ad3e50..31e643795016 100644
> --- a/fs/ext4/ioctl.c
> +++ b/fs/ext4/ioctl.c
> @@ -1159,14 +1159,16 @@ static int ext4_ioctl_getuuid(struct ext4_sb_info=
 *sbi,
> 		return 0;
> 	}
>=20
> -	if (fsuuid.fsu_len !=3D UUID_SIZE || fsuuid.fsu_flags !=3D 0)
> +	if (fsuuid.fsu_len < UUID_SIZE || fsuuid.fsu_flags !=3D 0)
> 		return -EINVAL;
>=20
> 	lock_buffer(sbi->s_sbh);
> 	memcpy(uuid, sbi->s_es->s_uuid, UUID_SIZE);
> 	unlock_buffer(sbi->s_sbh);
>=20
> -	if (copy_to_user(&ufsuuid->fsu_uuid[0], uuid, UUID_SIZE))
> +	fsuuid.fsu_len =3D UUID_SIZE;
> +	if (copy_to_user(ufsuuid, &fsuuid, sizeof(fsuuid)) ||
> +	    copy_to_user(&ufsuuid->fsu_uuid[0], uuid, UUID_SIZE))
> 		return -EFAULT;
> 	return 0;
> }
>=20