=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
net/xfrm/xfrm_user.c:1630 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
locks held by syz.0.0/5317: 1, last CPU#0:
 #0: ffff8880128d1c90 (&net->xfrm.xfrm_cfg_mutex){+.+.}-{4:4}, at: xfrm_netlink_rcv+0x6a/0x90 net/xfrm/xfrm_user.c:3928

stack backtrace:
CPU: 0 UID: 0 PID: 5317 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6938
 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+0x1703/0x1e50 net/xfrm/xfrm_user.c:3507
 xfrm_user_rcv_msg+0x7a8/0xf30 net/xfrm/xfrm_user.c:3907
 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
 xfrm_netlink_rcv+0x79/0x90 net/xfrm/xfrm_user.c:3929
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:800
 __sock_sendmsg net/socket.c:815 [inline]
 ____sys_sendmsg+0x54e/0x850 net/socket.c:2713
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2767
 __sys_sendmsg net/socket.c:2799 [inline]
 __do_sys_sendmsg net/socket.c:2804 [inline]
 __se_sys_sendmsg net/socket.c:2802 [inline]
 __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2802
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd6d199e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd6d2828fe8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fd6d1c26090 RCX: 00007fd6d199e159
RDX: 0000000000000000 RSI: 0000200000000500 RDI: 0000000000000010
RBP: 00007fd6d1a35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd6d1c26128 R14: 00007fd6d1c26090 R15: 00007ffdf561f508
 </TASK>