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Wed, 8 Sep 2021 18:47:58 +0000 From: Stephen Brennan To: Al Viro Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/3] namei: fix use-after-free and adjust calling conventions In-Reply-To: References: <20210901175144.121048-1-stephen.s.brennan@oracle.com> Date: Wed, 08 Sep 2021 11:47:59 -0700 Message-ID: <87mtomsy3k.fsf@stepbren-lnx.us.oracle.com> Content-Type: text/plain X-ClientProxiedBy: SJ0PR03CA0315.namprd03.prod.outlook.com (2603:10b6:a03:39d::20) To CH2PR10MB4166.namprd10.prod.outlook.com (2603:10b6:610:78::20) MIME-Version: 1.0 Received: from localhost (137.254.7.171) by SJ0PR03CA0315.namprd03.prod.outlook.com (2603:10b6:a03:39d::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4500.14 via Frontend Transport; Wed, 8 Sep 2021 18:47:57 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 474e0d7b-0d02-4ca3-9d3c-08d972f92cff X-MS-TrafficTypeDiagnostic: CH0PR10MB4986: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:200; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?fyXstCtChJRPzz4vGSoRX5Vb5HpGKbA4vsELy6cLpMiLv8bO7DSM2GvYx3E3?= =?us-ascii?Q?7DnlnGCNPUn4kV6LwDx06vu9Vx6hABivABNFZM0aocLI9CJjnNmqWPLH/zCd?= =?us-ascii?Q?mOdoUl1Y2gDtcmNJwJEshLDxx6b4iSvgicq2XmwWjmIT1C3v5zospiHSQMQA?= =?us-ascii?Q?XKHK/jZAocMEC/w4wY1vxodSnWWce7CKWVri6OZagjzPiF6eHLcqP4Bvu1Jp?= =?us-ascii?Q?Ohjk7yGOPkSxdkzsGGIrt4P1Mrp7AnzTb2KxFXT3BcBDp+klm1dSFzSVIU4v?= =?us-ascii?Q?VJ6/nShbDAT/k3OMmpZLiW63dO/iv8/IulZF3BH0MONKR/VNE3quXI4qPHIk?= =?us-ascii?Q?pC6rp2Dzb1GBUVRDOcOIgB6GtH8rd+vu09e5Pd+ggNj5+s0tV+RJGQs2yTag?= =?us-ascii?Q?dIsBOlzY7XU8Pqkj5oyRR09P82j6uKDGNkwWWuTPnLZlEU8fVDmqB8M0ECSr?= =?us-ascii?Q?GKBt+rVE6hlSXJ0LjeCrlZ3dkOcKA/UfbBB7Ezoyv5suqdX9eId9Au5AQEU0?= =?us-ascii?Q?OK9MGlqBHZLbdlkuW7XwBFQ3Lq4Wc0bJXHeFHrjJU9bDxgsyKY4/eVv5Uuxs?= =?us-ascii?Q?4Yr6oVPC9JCJWN0OGIGeAdl3VCora3PS0PlOFGHUxhepfoJtxwT9VLSVgjZ7?= =?us-ascii?Q?79gS3jBaUG3OQA2z5uLHZBHqhj8pYjXXVQXxIu5wLRn/xMZuYKsref0SXxZM?= =?us-ascii?Q?kSqMhz0JV8AejDq4gx5cCXjMh11+44CSAjt+ceNQ61MNksRR5TyCt0v+y3qs?= =?us-ascii?Q?8c8AOruXKtofdHWFr2viCUxr/D42b0MqaKbSsZjuvPNIAq1oZ62gbEiXON6u?= =?us-ascii?Q?eCKizEIyEza3vbWED7HI5qswuNIhS8a+z4W+wVzw7BSCMZL7QunbutKQc3r4?= =?us-ascii?Q?pcUzBUj6i61g12lg2hDri00SCy66/6ChcD1f9j7mJqMKLDlaW4QSfm/NtxEC?= =?us-ascii?Q?PhASHn4ulRFooDR/DhyVfSxQNRRu6XvJXhi0725pB4rehooJdvpamcZC8k4w?= =?us-ascii?Q?7JhIp574r1UFMbEOBywDtaXVWUP34UU/btkjl5uhqx6aMWhRoEmsKqxR32dV?= =?us-ascii?Q?GLGMZdiaOItVQjP4ez/8VeQ2kGke9BDWUmthrjfB0wpCpRp3NiR0WARaGzkX?= =?us-ascii?Q?MDum1/rzjofrXoRDQwaYagOQTq+NtKWjj4iiZykS8KsqoZ/iqRDcbZ0I/g+2?= =?us-ascii?Q?EloczorgCJFmfZR0KU07x19FgbuRaIWs0xxa6ZcldUPFbaC/5yDU67grXG+3?= =?us-ascii?Q?wc3sJrH8HpChL5ky2af630vVtb6+oCU/cdq77wEDFGRvXNOczlYfT4q+dzus?= =?us-ascii?Q?Uy9O1jag4qTHm+RC+ODyK1Cu?= X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: 474e0d7b-0d02-4ca3-9d3c-08d972f92cff X-MS-Exchange-CrossTenant-AuthSource: CH2PR10MB4166.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Sep 2021 18:47:57.9855 (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: 5qE+DeIKoETeW4UDtFPz6mso//+qsXxiYYnIOLVa8TwHFxOXtlXAq1LygEw9oZYYpmQZjtM/dlfdA2N5zwLWqbrd2l0hxULhkyphmHsh0Zc= X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH0PR10MB4986 X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10101 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 mlxlogscore=999 bulkscore=0 suspectscore=0 mlxscore=0 phishscore=0 malwarescore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2109030001 definitions=main-2109080117 X-Proofpoint-GUID: 8sXFP1yOilDjSTmbvY0rpy3Lx7GcHdCy X-Proofpoint-ORIG-GUID: 8sXFP1yOilDjSTmbvY0rpy3Lx7GcHdCy Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Al Viro writes: > [snip] > Another part I really dislike in that area (not your fault, obviously) > is > > void putname(struct filename *name) > { > if (IS_ERR_OR_NULL(name)) > return; > > in mainline right now. Could somebody explain when the hell has NULL > become a possibility here? OK, I buy putname(ERR_PTR(...)) being > a no-op, but IME every sodding time we mixed NULL and ERR_PTR() in > an API we ended up with headache later. > > IS_ERR_OR_NULL() is almost always wrong. NULL as argument > for destructor makes sense when constructor can fail with NULL; > not the case here. > > How about the variant in vfs.git#misc.namei? I went and looked through the changelog of fs/namei.c since this was changed and don't see anything setting a filename NULL, so it seems safe and good to me. I couldn't check *every* user of filename but the change was only two months ago. Feel free to use my r-b for that commit if you want. Reviewed-by: Stephen Brennan