From: Aleksandr Nogikh xfrm_nlmsg_multicast() requires the RCU read lock to be held because it safely dereferences the net->xfrm.nlsk pointer using rcu_dereference(). When it is called from xfrm_send_migrate_state(), the RCU read lock is not held, which triggers a suspicious RCU usage warning: WARNING: suspicious RCU usage net/xfrm/xfrm_user.c:1630 suspicious rcu_dereference_check() usage! Call Trace: lockdep_rcu_suspicious+0x13f/0x1d0 kernel/locking/lockdep.c:6876 xfrm_nlmsg_multicast+0x1d8/0x1f0 net/xfrm/xfrm_user.c:1630 xfrm_send_migrate_state+0x870/0xae0 net/xfrm/xfrm_user.c:3340 xfrm_do_migrate_state+0x1749/0x1e90 net/xfrm/xfrm_user.c:3507 xfrm_user_rcv_msg+0x7a8/0xf30 net/xfrm/xfrm_user.c:3907 Fix this by wrapping the xfrm_nlmsg_multicast() call in xfrm_send_migrate_state() with rcu_read_lock() and rcu_read_unlock(). Fixes: a9d155ea9b44 ("xfrm: add XFRM_MSG_MIGRATE_STATE for single SA migration") Assisted-by: Gemini:gemini-3.5-flash Gemini:gemini-3.1-pro-preview syzbot Reported-by: syzbot+c0e99a1aa85a286d7a3b@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=c0e99a1aa85a286d7a3b Link: https://syzkaller.appspot.com/ai_job?id=8977f559-3a7e-4bb5-b4d6-1196956260b6 Signed-off-by: Aleksandr Nogikh --- diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index d6db63304..0ba0614d6 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -3337,7 +3337,11 @@ static int xfrm_send_migrate_state(struct net *net, return err; } - return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_MIGRATE); + rcu_read_lock(); + err = xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_MIGRATE); + rcu_read_unlock(); + + return err; } static int xfrm_do_migrate_state(struct sk_buff *skb, struct nlmsghdr *nlh, base-commit: f5098b6bae761e346ebcd9da7f95622c04733cff -- See https://goo.gle/syzbot-ai-patches for information about AI-generated patches. You can comment on the patch as usual, syzbot will try to address the comments and send a new version of the patch if necessary. syzbot engineers can be reached at syzkaller@googlegroups.com.