=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
net/netfilter/nf_conntrack_netlink.c:3393 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
locks held by syz.0.1635/11824: 2, last CPU#0:
 #0: ffffffff9aee4320 (nfnl_subsys_ctnetlink_exp){+.+.}-{4:4}, at: nfnetlink_rcv_msg+0xa69/0x12b0
 #1: ffffffff8ea74d58 (nf_conntrack_expect_lock){+.-.}-{3:3}, at: nf_ct_expect_iterate_net+0x38/0x180

stack backtrace:
CPU: 0 UID: 0 PID: 11824 Comm: syz.0.1635 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 lockdep_rcu_suspicious+0x140/0x1d0
 expect_iter_name+0xfb/0x100
 nf_ct_expect_iterate_net+0xf2/0x180
 ctnetlink_del_expect+0x45d/0x640
 nfnetlink_rcv_msg+0xcc2/0x12b0
 netlink_rcv_skb+0x226/0x4a0
 nfnetlink_rcv+0x2b9/0x28c0
 netlink_unicast+0x7bd/0x940
 netlink_sendmsg+0x813/0xb40
 sock_sendmsg_nosec+0x13a/0x180
 ____sys_sendmsg+0x54e/0x850
 ___sys_sendmsg+0x2a5/0x360
 __x64_sys_sendmsg+0x1b1/0x290
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2b0fb9e159
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:00007f2b10981028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f2b0fe25fa0 RCX: 00007f2b0fb9e159
RDX: 0000000004000000 RSI: 0000200000005140 RDI: 0000000000000009
RBP: 00007f2b0fc3506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2b0fe26038 R14: 00007f2b0fe25fa0 R15: 00007fffa7b682c8
 </TASK>
