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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Omid Ehtemam-Haghighi , linux-kernel@vger.kernel.org Subject: Re: [PATCH net 2/2] ipv6: fix possible infinite loop in fib6_select_path() Message-ID: <20260528084518.GB592092@shredder> References: <20260527053133.180695-1-jiayuan.chen@linux.dev> <20260527053133.180695-2-jiayuan.chen@linux.dev> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260527053133.180695-2-jiayuan.chen@linux.dev> X-ClientProxiedBy: FR4P281CA0150.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:b8::16) 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_|IA1PR12MB8311:EE_ X-MS-Office365-Filtering-Correlation-Id: 66f60357-adee-4100-538d-08debc95794a X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|7416014|376014|4143699003|11063799006|56012099006|18002099003|22082099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?ojExeS+dudKLR3MijVnZqqqCpT6YjI4AQEKGjAzzAyLqhYydGXTHvNdZWU3B?= =?us-ascii?Q?6iOuAp5QtPTLw+zoVx7+cUZhe15u69t0XMlyY1U41J/Npiz9NN8nTzCKugDL?= =?us-ascii?Q?Vuwz9Hs5gI0esmESo1KwWrdVYMgYM2DX3NJnoxJaX6p1jImYDXX7wefoeOpZ?= =?us-ascii?Q?49x1eRmUEELWZ/DBEPYejyBRgFM2+xeF8rgQKpW18AaJ+D7xNLVI9OYiqruL?= =?us-ascii?Q?bHDAp7cY/S8CpxZCT6RCQjIGQE77FTNkSit/ss4IVjBYy1IMoeW6oa/YNYSY?= =?us-ascii?Q?7jzVGHJqM2USrhMzd4lZH2DAQ/k7Piq+pnhL9z07ZKzoyb/LYFXubbrRFocg?= =?us-ascii?Q?FHmLNi2mo/XLC2VAW2gurdl1fD/S6kyfIbuOCfLBMI2AisNs+rhY1uQMnBa4?= =?us-ascii?Q?D50eoXnHEGlVz8MUhKg0aQtj2Y6AB8wfadib43Jol9WL6MLNhTR6PXtRuxXy?= =?us-ascii?Q?GphbkH/6XO8dQWdgU+YFXyp3QMpHMfC6i9S5BLO6y+i0CqbsLLBWM4bQsVaI?= =?us-ascii?Q?80Pti3mpnu4jdaPtk2xkTF/S5Q4nUf/hRiDNiavCKgMHwXX0H0mHQP8FoHhj?= =?us-ascii?Q?4rRK/OFjEqiwiuizuvgwtTo/EldC1QxvnQL3J0ZzcRLeCoiSaY4RDXSYJzXB?= =?us-ascii?Q?DMYJE1Ih7C9f2HIfESC/Q2bGzL3440atnTMu9y/OgAouyxSoLttBIkLEFe0p?= =?us-ascii?Q?qWyef/0vCvcCItLg9RSBqUQTxcQ7rauYZ/pJnt0o9FSPozSQYWItxJOmKIjj?= =?us-ascii?Q?5C92ajcVI6RHk4qDt4wC0aPjwzaG/43kYrV32B63rM5ojhVK+vWTMRbOKhOd?= =?us-ascii?Q?16uGC3t9FGQ/e6SAaslyx9+9+vQaK+OXv3J/kV3D0FVPvKiFQmSZyJ8ypA08?= =?us-ascii?Q?mRDLNbgMC24VmAflpOQIhewDMBT53KoW08ObT57ktUjQVK3NE/E+j5KF0WDu?= =?us-ascii?Q?u4oxB06YP9WbLkseLfcw6VALh2UKZ2+Qs8366hqzkTB8Jm3ynG1OE6JBLZCb?= =?us-ascii?Q?elNTTzyzzeeRHwE4+R3wxIZcQ+p6ZZjsrWjdXJnZ1YXFNXOnBmLa34249ZtP?= =?us-ascii?Q?E7359pXHTJ4T6R0Ek8c+MlogseRAEM18b2QmHHAb1qc0wTmwZoLH+qdYewPZ?= =?us-ascii?Q?0ojcKgTlsE06bCzjrJOdGIOlXlAcaSD10pswCqv4viLw5mU1TFXGdXT0hLmw?= =?us-ascii?Q?RDl31TlCgPHENqgnc2eaMm0MTNve4KEvOjU/JNS2hG2FRJiHNjd3VI5lNY0L?= =?us-ascii?Q?cQ6GUUs2+g4w134KnZznll5FC59iEVI43Omwq/aSCrV/YCUYPymZWnxn2kaD?= =?us-ascii?Q?wUGqlzeOJ9wWgEmxFjS2eYVkrE5IDhWaaKwDpOfSxEHb+Br+y3GpKXs7hPjL?= =?us-ascii?Q?Ez3tLmk/xwwZWE5dAFp/mNM2Wg5bNB+hJhplzeTXIhsJN6cDaSIOgswAXhJ7?= =?us-ascii?Q?NyAULDb/5OWHh0la1+O0G1B+mS8ahXUUIgIF6V6WsC2uOreVPgZWL1V9IIcF?= =?us-ascii?Q?wqRoa+gM+9XmVMKZHEjg3dJUYCIBuVHKLjV1dqRjavpCLwqAc6tpU84r0rvF?= =?us-ascii?Q?IcEyKLprzBxavHekRlCwFuahY6DREhHnypt8StGvLpL5tMhqZBnv+LkGyOIj?= =?us-ascii?Q?hQWRkS/QSf2TLoe5gTxveb7WjcjFNBg7bsr5zv6+MJgp7yr5P0LgKNZcc9Rg?= =?us-ascii?Q?wVZWbg6ZI02tc118/xixIsJSKwrF5Gf+AfgkjjN5uee1pOyeSpwnuDFSUrxW?= =?us-ascii?Q?68G9yn6f7A=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 66f60357-adee-4100-538d-08debc95794a X-MS-Exchange-CrossTenant-AuthSource: SA3PR12MB7901.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 May 2026 08:45:30.5273 (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: w+Ye0OR0lswk5A6TCxQ3HAmDRMaGIWZ3Vtl6/c+xR4zd4q/AyM9qCEegIS+raQr0DE4iigCy6DOLrTZQ3tztCQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB8311 On Wed, May 27, 2026 at 01:31:31PM +0800, Jiayuan Chen wrote: > Found while auditing the same pattern Sashiko reported in > rt6_fill_node() [1]. Apply the same fix as > commit f8d8ce1b515a ("ipv6: fix possible infinite loop in fib6_info_uses_dev()"). > > Writers holding tb6_lock can list_del_rcu(&first->fib6_siblings) > without waiting for RCU readers; first->fib6_siblings.next then > still points into the old ring and this softirq-side walker never > reaches &first->fib6_siblings as its terminator. fib6_purge_rt() > always WRITE_ONCE()s first->fib6_nsiblings to 0 before > list_del_rcu(), so an inside-loop check is a reliable detach signal. > > [1] https://sashiko.dev/#/patchset/20260526020227.4857-1-jiayuan.chen%40linux.dev > > Fixes: d9ccb18f83ea ("ipv6: Fix soft lockups in fib6_select_path under high next hop churn") > Signed-off-by: Jiayuan Chen Reviewed-by: Ido Schimmel