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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Yifan Wu , Juefei Pu , Yuan Tan , Xin Liu , Haoze Xie Subject: Re: [PATCH net 1/1] net: l3mdev: Ignore non-L3 uppers in l3mdev_fib_table_rcu Message-ID: <20260406103350.GA654671@shredder> References: Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: TL2P290CA0028.ISRP290.PROD.OUTLOOK.COM (2603:1096:950:3::10) To SA3PR12MB7901.namprd12.prod.outlook.com (2603:10b6:806:306::12) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SA3PR12MB7901:EE_|SJ2PR12MB9191:EE_ X-MS-Office365-Filtering-Correlation-Id: 60b5da29-ff17-4fd8-e9df-08de93c802b1 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|1800799024|366016|18002099003|22082099003|56012099003; X-Microsoft-Antispam-Message-Info: KpBrC/Oi+VdANtza6WrsAXbTofHDhuDCYuJLDP/e5vHr4ebPSiRMwVXXKf6cqTvCrvUXNPqkWO4FzDdVJmRjLwY43YFJ9s6j3T3Aa6/PmqdSmkMBmPzZPzyFwNOAZQB4IBxL9uCMBOht7z3+4Vsk+twam3+aooMbm1B3G9qSesdO3WT9bXFmpbfcmmZeuBJPquhb9umRJhQ4G5pTFRlzViHldwjhYygaJxxwzgenxYJbWRlHXwiEhHYxMLxGzXznX5LI6ksk6pwXroRtaQb/4YPn735ZjEc4o5G0+GOHEd8s2wRVB7uRrQJtZfsrMMQiiKU6eWqOaj+fCtDuG8cQ/TKwtYrOMcW2X4KsWNMjDVYb4Mp/tJaZymfLHFCumghuLsoMEf3pMdzRF1+qm5UIq62jKkAuvMFapKtXzShLffES68JxkavfSCTZMZ0zdF9WyE9cyDj8xD8taDvltadL7XL+kzB+EMsPd22/hAwRmAmWoy7pJ0qg5h9MndBFCMMnP8626eLQyVwsjlXSOJvD9pkiAfNUqO3T4iaNuEjFL9jC7K+96Z8smopAk/xcUxzoeUckvZEhlAnJO1E47ZguGKgy1BoqpO17jlzzGDOJe4fc2SXEq3gNA6gQvP+6ZPGxm4C1A4HufzpTJfrUQ8a3DixzQTOMirXWOKSgM4xITfNlyuNCva5XXUSc8DdGgi9gMwgIoIeKyNqHaNIYlKaiU7Ulj+rN7bdWUMTDwbmdK90= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SA3PR12MB7901.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(376014)(7416014)(1800799024)(366016)(18002099003)(22082099003)(56012099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?3QTqFybWQc6UBXxob7Ckh9ROOHpI+9r3NnQQ6VKEMnDRfr3bG6Iwa9MS8zFj?= =?us-ascii?Q?UjNfOulBp+p47VP2bYgBdC+rU/ZAcgUUW2PW3vFrYx/5KHdejgUBG9lSvda6?= =?us-ascii?Q?tWOx9qxXvbu0vPF5zRNW5jEDj3qn+NDa6oNpzt5gonGAp63irkFZ0/u3I6W3?= =?us-ascii?Q?nEpfzd1y6jZqMhLgFLH7TkY+6gMOjAByI8WkcK0JgyfzMJuUJl4ir+QLzCaZ?= =?us-ascii?Q?nJY/zWt3LZ3SiM+S+hUE70mz8956bO6R7J3Sajs7vnO7RxVziMVVf9ApNx55?= =?us-ascii?Q?+6IOZEBD67DGdXxpiHrnriWS5wKfe9cx0ZQD90iOIFirJI34UCMe9Vx1AspZ?= =?us-ascii?Q?r9MDPd+pshhOTmiu5sDW2phhpMt279jFvE/f17ovFM3p5gvb0xItePAbYDfo?= =?us-ascii?Q?8vK8ZN056jbGLxKlYShcZoXwHRIA0C3/h6JK5EIr9IAFpPU57tz0Q9X6XJuJ?= =?us-ascii?Q?R+W4jw1dQnT6f0LmYii78eDu17RkH6GBWlsXLzC19R1S6pjMCjvqLt7qKSlI?= =?us-ascii?Q?6jc47cceGINcF1Vr9AhIKHUtJG9nGLbcGbvABRXbwJy+rLOZMiwB/Q3j0Bi8?= =?us-ascii?Q?fYr2vysctejJdTMtKQeuAVSr/OTr8i32fdx8bNiGArf1Dcx38+nKVodesBtk?= =?us-ascii?Q?E6OhkUqMApcGYBFdKrmX6W0LSJJMmUtss2kuoykEYhV5LncoBOXo244AOF+I?= =?us-ascii?Q?qGOd7dZXabIYlr2m7f9A+wTgsgNaIncssE9WYUmegQzD3gCNnObX8I+i45fT?= =?us-ascii?Q?yrAOs9h9Gq3qFgrWwEERt5dcJScuQrMIXjs6IwUu8HrFbz40bMiazJRgXcRL?= =?us-ascii?Q?W3Ndf8kNo4RcldCYD4MgAhB3m8W8AOmznGSnV2qHkNn0B4maP0LUsmMldtLr?= =?us-ascii?Q?E/KIxQgO0bw1sT4YNXmspBmVwbrNtbAzExh7kAp+LEED/0rAsGjloU1M0tnO?= =?us-ascii?Q?7Q2tnm6At3EeMEKYxaLvFv9Utyt8W7NJREMFVQiuJ0aaMRqxfP70fsb1TjyR?= =?us-ascii?Q?aB5B0ddJXZTWrAUZd8NOHbxjpa0ExTj6CskrWFUoFXEQXW/XaCYP6tmK4zgk?= =?us-ascii?Q?Calpha14nHKgSYT8HgK2/g16dks4P6c5N6WC4uN9syVL6+Orgy6ik1JaoBFt?= =?us-ascii?Q?NextqzT36c17f9ML+4axjMbL6sFs2+GB5cFpq/ve/s521+xEyqGlml1AM2e6?= =?us-ascii?Q?7xyjhPC6QOecmLAA+Oc3flNdF/rXm/TWa8ygv447efSU4AS2vAbFJWN2CcQF?= =?us-ascii?Q?rD0TV6KYgKUh16w3lTAIWGa90tfdnxw0eBOnkeLBngd8KlCb1ZFqdoK+bZ8R?= =?us-ascii?Q?NJmbIexdnVOLeh5+33gCnaTub2vmdb5xe8v7MAJ2zrkIvAFaNz1v08AvYpPm?= =?us-ascii?Q?t8PMNB+k0s3e6Ti8ZiQsltGjfXKAltDwNrJUwdfif382WedC7i4ZLYBWZGaf?= =?us-ascii?Q?0uE/22ZfylT9oNpqOE10xgrUwUf8jnPuUWSrXpOTDOjzdmvfB5yv9Spj6g25?= =?us-ascii?Q?KomAfjGim3DC14WqmWEeR/cXyJi1p97HC2/7xh9iVaQV2DEBZiTrC+B8BP4c?= =?us-ascii?Q?OOnXvyGOskxEYcUTlDUrNr7YF4ah7Yryyn6r/CXT9aGehgEENKgDNNQWOsil?= =?us-ascii?Q?DMNjB4jqivNiXCsNEeP7PsaYAkDjSiUS44gTzZ2UAxCaKQiiV4mE50DiMiqa?= =?us-ascii?Q?HTWcwv10hFO8Pr1YRMDp7cevBiZBgAe7+g/KJVPNKDggr/dx+acPBLHI3Yjn?= =?us-ascii?Q?76FHIlUEWg=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 60b5da29-ff17-4fd8-e9df-08de93c802b1 X-MS-Exchange-CrossTenant-AuthSource: SA3PR12MB7901.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Apr 2026 10:33:58.3727 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: yc97Y5q/aEMMCFPc5MAUOlg5Ug8c6rb4HI/xeG7OFUjlQQWeMDTtweSi0YrhcZvZ38E5FyvGoaReYD9vWRuaSg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB9191 On Sat, Apr 04, 2026 at 07:52:03PM +0800, Ao Zhou wrote: > From: Haoze Xie > > l3mdev_fib_table_rcu() assumes that any upper device observed for > an IFF_L3MDEV_SLAVE device is an L3 master and dereferences > master->l3mdev_ops unconditionally. > > VRF slave setup sets IFF_L3MDEV_SLAVE before the upper link is fully > switched, so readers can transiently observe a non-L3 upper such as a > bridge and follow a NULL l3mdev_ops pointer. Require the current upper > to still be an L3 master before consulting its FIB table. Do you have a reproducer? I don't see how that can happen. do_set_master() ensures that the device doesn't have a master when ndo_add_slave() is called. Meaning, if netif_is_l3_slave() is true and netdev_master_upper_dev_get_rcu() resolved a master device, it's guaranteed to be a VRF. > > Fixes: fee6d4c777a1 ("net: Add netif_is_l3_slave") > Reported-by: Yifan Wu > Reported-by: Juefei Pu > Co-developed-by: Yuan Tan > Signed-off-by: Yuan Tan > Suggested-by: Xin Liu > Signed-off-by: Haoze Xie > Signed-off-by: Ao Zhou > --- > net/l3mdev/l3mdev.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/l3mdev/l3mdev.c b/net/l3mdev/l3mdev.c > index 5432a5f2dfc8..b8a3030cb2c4 100644 > --- a/net/l3mdev/l3mdev.c > +++ b/net/l3mdev/l3mdev.c > @@ -177,7 +177,7 @@ u32 l3mdev_fib_table_rcu(const struct net_device *dev) > const struct net_device *master; > > master = netdev_master_upper_dev_get_rcu(_dev); > - if (master && > + if (master && netif_is_l3_master(master) && > master->l3mdev_ops->l3mdev_fib_table) > tb_id = master->l3mdev_ops->l3mdev_fib_table(master); > } > -- > 2.53.0 >