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emacs 29.4 From: Petr Machata To: Eric Dumazet CC: "David S . Miller" , Jakub Kicinski , Paolo Abeni , Simon Horman , Kuniyuki Iwashima , David Ahern , , , , Petr Machata , Roopa Prabhu , Nikolay Aleksandrov , Benjamin Poirier , Ido Schimmel Subject: Re: [PATCH net-next] ipv6: guard ip6_mr_output() with rcu Date: Fri, 27 Jun 2025 16:50:59 +0200 In-Reply-To: <20250627115822.3741390-1-edumazet@google.com> Message-ID: <87ecv5kzks.fsf@nvidia.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-ClientProxiedBy: rnnvmail202.nvidia.com (10.129.68.7) To rnnvmail201.nvidia.com (10.129.68.8) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MWH0EPF000A6731:EE_|SJ0PR12MB6880:EE_ X-MS-Office365-Filtering-Correlation-Id: 83752db5-047c-448a-5991-08ddb58a232d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|36860700013|82310400026|376014|7416014|7053199007; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?b7TJUkEb5Rbf9LfSm8s2VFTzeq5rLvJnbGKMXQlT+X/Hke76VhRCw/pTn0SX?= =?us-ascii?Q?p450z/GkqnzjRY/nqtLzx2UC4OXO1U392DQFErPJ7CUj0rsPSBGMkQ0lLe2B?= =?us-ascii?Q?uPCX9iTQWD59x1hjq0iBorHdGcl+tmsW0ZnFavGWaVAUhvEdg8+NPketBmPh?= =?us-ascii?Q?beBcB0ZAiUcmuMYX4U96DegIByLAaVRJgD/GVm+josvFl3ncM7OnWvAINUjr?= =?us-ascii?Q?5VV3Qack8EmYnBJN3xQF19IQkfazVKapNiloOvC5kdFF25t1fiZxekj7AcaB?= =?us-ascii?Q?fwacXJXFaLQ/DM8DcZtdse7oQ2H5+uVWGyHiZ1ijs6mbRpcvVIM3UL7U/nny?= =?us-ascii?Q?yRtIJCyvyB+ev612BlYVGj5F8L+CPvyEWp/hPJImB29veUatlB1n3Z9J2XdD?= =?us-ascii?Q?4hbq7FxwFsmlRPscySMfTYDpm3aLGKuFHw70cjmkp+fjeLjWvjmfMqO3EdDH?= =?us-ascii?Q?opP6j5titUWHEe5jXipCyeNOXNUYdLG0y5uTwW9OGGGT5M3qOPLRPHytaXgn?= =?us-ascii?Q?IH55C4FQjfpNl6r1tp7Y7xsR455IcYfDVwPfcgIs6KjHgphl84Ct+Jby7RIQ?= =?us-ascii?Q?5K2s6de3Mq1yXSkdu382hb6cvlX2ZNPtnN04BnFIwn7hfmkRDNQfn/6CwEsW?= =?us-ascii?Q?gCaIpktjQUrkKgrHLFTzn/qGrZEDGSvoPozvdNuAIKFBLW3dvE1Sng57bSeU?= =?us-ascii?Q?UychKtZbpK+PbIND+HXS6DWemkIXEKF9ld7wJdPTlfUiX7yiQAdGxXCipLjP?= =?us-ascii?Q?Yuerwyou/YvAGJ5Ty/5DZ90RmqgL+BhsTy4BQ6/zPBFfWxBCTNvkuDNFAQ76?= =?us-ascii?Q?ReQKn1X7JdfuuVFWP1tq5Cyhk+ELL8461l0ti1ok/CiPnRUV0Uhc//TNnfp5?= =?us-ascii?Q?ER6MMT8QKpur7ckCxpbKOdme3rbSAWTnp7Qvc7ggI+0ABWcFczip4EurVBw3?= =?us-ascii?Q?LskFsMplQJC+7VhyqHxGC0V0XyfsDoy84C7U8V7SMAHqH2O53FFXHEIaPc9v?= =?us-ascii?Q?hOm+UItzkh9/y98TmLtIy/uW9THhKymeaEBui2j3pL5yYgBpG/TlB+447WsE?= =?us-ascii?Q?9D2tBUPc+OhXlTvsVeijq/cIzlvUB93Q/cqy2e3oGCzIjY+2NRNXRynKESSU?= =?us-ascii?Q?CYuYRKu5Np5jvZ7zgpGXFhChpFvRVGdYiyT0wZQQMQAUmJ47+q+dnk0GvsHk?= =?us-ascii?Q?ovFWSVXa5gU3rbfnzBh+RNy6DzmKsg9BafCuzo/IfkYo9bzpMqBxBHz0j7TY?= =?us-ascii?Q?5sgdqFS8QLEaHonTkXDma0wz1DGDVYcaae4hXZb+TeWdfE5s64Xnd50wV+3r?= =?us-ascii?Q?tZIloQtjFooFCO9FZO1FENniYCizU+278HKBHnrPMX0vseEkHgEMmyarFxSh?= =?us-ascii?Q?Owy1PInRQnmY+vnwP14M3bueQ6KadTwOKm2YaKutjk0zsCAgx02h3zlX2I59?= =?us-ascii?Q?2qYiLIrysRiY0MpfOLXgtN/bmFNfzvPvG35WDZ2xfaGW1ZbhRrQVuZDEhu5H?= =?us-ascii?Q?RVPECwtPdqwSpgVjjmi8Fk3+b+5euadNjhIE?= X-Forefront-Antispam-Report: CIP:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230040)(1800799024)(36860700013)(82310400026)(376014)(7416014)(7053199007);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 Jun 2025 14:51:45.5852 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 83752db5-047c-448a-5991-08ddb58a232d X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: MWH0EPF000A6731.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR12MB6880 Eric Dumazet writes: > syzbot found at least one path leads to an ip_mr_output() > without RCU being held. > > Add guard(rcu)() to fix this in a concise way. > > WARNING: net/ipv6/ip6mr.c:2376 at ip6_mr_output+0xe0b/0x1040 net/ipv6/ip6mr.c:2376, CPU#1: kworker/1:2/121 > Call Trace: > > ip6tunnel_xmit include/net/ip6_tunnel.h:162 [inline] > udp_tunnel6_xmit_skb+0x640/0xad0 net/ipv6/ip6_udp_tunnel.c:112 > send6+0x5ac/0x8d0 drivers/net/wireguard/socket.c:152 > wg_socket_send_skb_to_peer+0x111/0x1d0 drivers/net/wireguard/socket.c:178 > wg_packet_create_data_done drivers/net/wireguard/send.c:251 [inline] > wg_packet_tx_worker+0x1c8/0x7c0 drivers/net/wireguard/send.c:276 > process_one_work kernel/workqueue.c:3239 [inline] > process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3322 > worker_thread+0x8a0/0xda0 kernel/workqueue.c:3403 > kthread+0x70e/0x8a0 kernel/kthread.c:464 > ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > > Fixes: 96e8f5a9fe2d ("net: ipv6: Add ip6_mr_output()") > Reported-by: syzbot+0141c834e47059395621@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/netdev/685e86b3.a00a0220.129264.0003.GAE@google.com/T/#u > Signed-off-by: Eric Dumazet > Cc: Petr Machata > Cc: Roopa Prabhu > Cc: Nikolay Aleksandrov > Cc: Benjamin Poirier > Cc: Ido Schimmel > --- > net/ipv6/ip6mr.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c > index a35f4f1c658960e4b087848461f3ea7af653d070..eb6a00262510f1cd6a9d48fab80bdd0d496bb7ee 100644 > --- a/net/ipv6/ip6mr.c > +++ b/net/ipv6/ip6mr.c > @@ -2373,7 +2373,7 @@ int ip6_mr_output(struct net *net, struct sock *sk, struct sk_buff *skb) > int err; > int vif; > > - WARN_ON_ONCE(!rcu_read_lock_held()); > + guard(rcu)(); > > if (IP6CB(skb)->flags & IP6SKB_FORWARDED) > goto ip6_output; Thanks for the fix! Reviewed-by: Petr Machata