=============================
WARNING: suspicious RCU usage
5.15.175-syzkaller #0 Not tainted
-----------------------------
net/sched/sch_api.c:304 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
8 locks held by kworker/u4:1/144:
 #0: ffff8880779ca938 ((wq_completion)wg-kex-wg2#5){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc9000176fd20 ((work_completion)(&peer->transmit_handshake_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff888025446898 (&peer->endpoint_lock){++-.}-{2:2}, at: wg_socket_send_skb_to_peer+0x56/0x1d0 drivers/net/wireguard/socket.c:173
 #3: ffffffff8cb1fd80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
 #4: ffffffff8cb1fd80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
 #5: ffffffff8cb1fd80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
 #6: ffff88807ad3f908 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
 #6: ffff88807ad3f908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3879 [inline]
 #6: ffff88807ad3f908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0xc1f/0x32b0 net/core/dev.c:4221
 #7: ffffffff8cb1fd20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311

stack backtrace:
CPU: 0 PID: 144 Comm: kworker/u4:1 Not tainted 5.15.175-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
Workqueue: wg-kex-wg2 wg_packet_handshake_send_worker
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 qdisc_lookup+0xa8/0x630 net/sched/sch_api.c:304
 qdisc_tree_reduce_backlog+0x212/0x4f0 net/sched/sch_api.c:800
 pfifo_tail_enqueue+0x2ca/0x400 net/sched/sch_fifo.c:51
 qdisc_enqueue include/net/sch_generic.h:832 [inline]
 tbf_enqueue+0x35d/0x6f0 net/sched/sch_tbf.c:243
 dev_qdisc_enqueue+0x47/0x240 net/core/dev.c:3820
 __dev_xmit_skb net/core/dev.c:3904 [inline]
 __dev_queue_xmit+0xe32/0x32b0 net/core/dev.c:4221
 neigh_hh_output include/net/neighbour.h:493 [inline]
 neigh_output include/net/neighbour.h:507 [inline]
 ip_finish_output2+0xcd7/0x11a0 net/ipv4/ip_output.c:228
 iptunnel_xmit+0x513/0x950 net/ipv4/ip_tunnel_core.c:82
 udp_tunnel_xmit_skb+0x1d0/0x2d0 net/ipv4/udp_tunnel_core.c:175
 send4+0x94a/0xf50 drivers/net/wireguard/socket.c:85
 wg_socket_send_skb_to_peer+0xd1/0x1d0 drivers/net/wireguard/socket.c:175
 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
 wg_packet_handshake_send_worker+0x1d9/0x310 drivers/net/wireguard/send.c:51
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>