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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Ido Schimmel , Jiri Pirko , Yifan Wu , Juefei Pu , Yuan Tan , Xin Liu , Haoze Xie Subject: Re: [PATCH net v2 1/1] net: l3mdev: Ignore non-L3 uppers in l3mdev_fib_table_rcu Message-ID: <20260406154808.GA714138@shredder> References: <429dd4a81d4ca5624ab9f6d7b53c5fe08552c734.1775443332.git.royenheart@gmail.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <429dd4a81d4ca5624ab9f6d7b53c5fe08552c734.1775443332.git.royenheart@gmail.com> 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_|SJ0PR12MB6853:EE_ X-MS-Office365-Filtering-Correlation-Id: 5a0dad48-9fe4-4f2c-b1d3-08de93f3ed1a X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|1800799024|7416014|376014|56012099003|18002099003|22082099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?VHpVMitYPcv38R931LlpwmX9ag3DsxHjkK1F122rjLi92Lc8WAiRlvP9bLiw?= =?us-ascii?Q?4TjXMkB2DSx7Tv6eCpszZQ5SAj9DXw9l+VkODeNKwPLNd7335KACR8lKolUw?= =?us-ascii?Q?8WqVwT5xwovWL6SxE9Zq4ll2Zp2x7UTe8h69EL+JZ7WWiDKwuFb6JxNIjhxu?= =?us-ascii?Q?qy80JUtOUpUPF8b5BoT0YO9yy/guhSlQV8glVjTt+OYnP9/SnyeN72FM34eZ?= =?us-ascii?Q?hYh6ucw2nWnRM77S0Cip/LWegRJEtrU0brD+NyF1qjGieNYeIXIXAMwx227z?= =?us-ascii?Q?Cv+HbRONxx99wLgwRPFL5aCkVAfRbi9nRjpU0qd0iudna9rgz90ivvQ0JCHq?= =?us-ascii?Q?w9Ma8SDnfUyHLqJ/2bwex8K6qEwF+NY25CXcszLBQZUOHHY/4qfaP8bUgAnt?= =?us-ascii?Q?lnf1cL8kTsEBQ8yrJQPnZlCvRz7eU4CqV06BR7oM6nhBt/0zy6ZUwS4kP5FK?= =?us-ascii?Q?lY0j+9bHFCujjKoIo4SuTtereeV6rpzNlJhsatGYbglKwtQlhyacFzhmPXK7?= =?us-ascii?Q?UAXRK2CG/kBa9pw0cNEyVVwieoSQwQQFeUf9wZFQaRCquMWrU/2B+UW5RtTH?= =?us-ascii?Q?YyJBQ9jgBWtzzlV9Pu/SP3jm/DjpeJOmPdozxx2hUi1aj3KI09xF/p8OVGWp?= =?us-ascii?Q?3o/cgG/w8UKAzpP/KV1zU6xq5W4u/k05/dXhouUyI7K99GqD7ojBnS8TPqNt?= =?us-ascii?Q?c7kH+gU2e8TNtVjP7CxBY/4/p5jOcw1emx9OLfj13/bUvWNEBGOJ8rqKCHvX?= =?us-ascii?Q?WO0CD7Ech+5LPmJmX++USHwgeUrRHPUOsrabN2AqZUns5JPMiWTgR5pWwdQo?= =?us-ascii?Q?cPLa9ccoRams+WtwJkjoOzmISY8HHUMRv1wgByAirKRcYxuqMeiBQ04PTBCu?= =?us-ascii?Q?0K5uESc6VinLqu8lKrhiXReAwSWB6o+nCBNcuvlyDw0nQFolBFkc/ID4iy1C?= =?us-ascii?Q?Bz33JCbYHoJHVJDNabTosTZzEZPo+ilwAmnC+cROMEXZMMi1vxd/ffLUYIGy?= =?us-ascii?Q?RhBeaTYwufjF37E9u22/PMkPcKYhDTZ2804dxL4jXJmNKi9xYCEbH5Ep9+yK?= =?us-ascii?Q?dahR7ZjP7k2dQgQEIOMA7nNFk+kctWzDpstSzTOVUJbYoGypyjYZtojwlbAM?= =?us-ascii?Q?7h1mQMkEspnEsTcewchda0nM2XJ2i9GKaJVh19tEe3qP7KEPTIOcsnosvTEu?= =?us-ascii?Q?5We2QVaFXPigp/X9YMQwjrcM5tTTpwFJItn8EibfOMAT5nwhPBvPA3YUPv+L?= =?us-ascii?Q?BMHUib3idr5Ho/5WVjGOGJalCiV/chmIO+F996jF3YGtB+9cAFpDaVKXZImh?= =?us-ascii?Q?tRduCsV/4H8twJ0FbaMGGVnYAxfv2+XpEBwV5T1bYwa6au7+nq59uOSqTZZk?= =?us-ascii?Q?2gLdhtSQiqqAhrGqckB6bI5AHQxS8sleM1Q1MUfLtAIFvB11zGwD+pVEhm1Z?= =?us-ascii?Q?Gznbg8x7p7LvRSSOfVe2GYMarN1pJ1nV5dbkR1l0v/XlojJseKAfYc3hAWSB?= =?us-ascii?Q?p8PqkYx4dgmMLDmZjrvyqwfNnUA03bdW5iHioOu2BL2xvZEc2dG6vAaamxa8?= =?us-ascii?Q?L3Oaikhfx2Tzh7fNu9Fsr0g4fhapbV7f9WkP0UdAIw+LltoozRnI6Gfv+9+9?= =?us-ascii?Q?lxWGXxmKCqwMfhr6bQH99BO/uq/iPUUOfbxpm/iXwAi2mlNmFNzmjDHGGWFe?= =?us-ascii?Q?ZPuDUgXgQ3/KQTVJAElzXLVBUzEG5EBiPNNNvYqSrK2QqAFRnmTe6QzErxMG?= =?us-ascii?Q?LGTR8RwMLg=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 5a0dad48-9fe4-4f2c-b1d3-08de93f3ed1a X-MS-Exchange-CrossTenant-AuthSource: SA3PR12MB7901.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Apr 2026 15:48:20.0023 (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: tbb5eDjlYyvO9yYYo7R3OQ4KeT+XviJ4YBJdizhiMBES9JIp34tOQM9fBawqW0Y7QHjHjuJ/YA8FH34XOD0Glg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR12MB6853 On Mon, Apr 06, 2026 at 09:28:16PM +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. > > Fixes: fdeea7be88b1 ("net: vrf: Set slave's private flag before linking") > Reported-by: Yifan Wu > Reported-by: Juefei Pu > Co-developed-by: Yuan Tan > Signed-off-by: Yuan Tan > Suggested-by: Xin Liu > Reviewed-by: David Ahern > Signed-off-by: Haoze Xie > Signed-off-by: Ao Zhou > --- > changes in v2: > - point Fixes to the VRF slave ordering change identified by David Ahern > - add David Ahern's Reviewed-by trailer > > 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) Don't we have the same problem in l3mdev_l3_rcv() and l3mdev_l3_out()? If so, please check if I missed more places and include them in v3. And I think that the part that I was missing earlier is that we don't have RCU synchronization in the unslaving path, so an RCU reader can either see the original master, NULL or a new master (e.g., bridge instead of the original VRF master). > tb_id = master->l3mdev_ops->l3mdev_fib_table(master); > } > -- > 2.53.0 >