=============================
WARNING: suspicious RCU usage
5.15.178-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
9 locks held by kworker/0:25/4315:
 #0: ffff88806007e938 ((wq_completion)wg-crypt-wg0#7){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc9000354fd20 ((work_completion)(&peer->transmit_packet_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff88801f6139b8 (&peer->endpoint_lock){++-.}-{2:2}, at: wg_socket_send_skb_to_peer+0x56/0x1d0 drivers/net/wireguard/socket.c:173
 #3: ffffffff8cb1fd40 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
 #4: ffffffff8cb1fd40 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
 #5: ffffffff8cb1fd40 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
 #6: ffff888078a77148 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: neigh_hh_output include/net/neighbour.h:493 [inline]
 #6: ffff888078a77148 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: neigh_output include/net/neighbour.h:507 [inline]
 #6: ffff888078a77148 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: ip6_finish_output2+0xead/0x15a0 net/ipv6/ip6_output.c:130
 #7: ffff888078a77108 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
 #7: ffff888078a77108 (&sch->q.lock){+.-.}-{2:2}, at: sch_direct_xmit+0x370/0x5e0 net/sched/sch_generic.c:354
 #8: ffffffff8cb1fce0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311

stack backtrace:
CPU: 0 PID: 4315 Comm: kworker/0:25 Not tainted 5.15.178-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: wg-crypt-wg0 wg_packet_tx_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
 cake_dequeue+0x2297/0x4600 net/sched/sch_cake.c:2179
 qdisc_peek_dequeued+0x6f/0x220 include/net/sch_generic.h:1100
 tbf_dequeue+0x80/0xd60 net/sched/sch_tbf.c:265
 dequeue_skb net/sched/sch_generic.c:292 [inline]
 qdisc_restart net/sched/sch_generic.c:397 [inline]
 __qdisc_run+0x253/0x1e90 net/sched/sch_generic.c:415
 __dev_xmit_skb net/core/dev.c:3910 [inline]
 __dev_queue_xmit+0xf78/0x32b0 net/core/dev.c:4221
 neigh_hh_output include/net/neighbour.h:493 [inline]
 neigh_output include/net/neighbour.h:507 [inline]
 ip6_finish_output2+0xead/0x15a0 net/ipv6/ip6_output.c:130
 ip6tunnel_xmit include/net/ip6_tunnel.h:160 [inline]
 udp_tunnel6_xmit_skb+0x538/0x970 net/ipv6/ip6_udp_tunnel.c:109
 send6+0x6a7/0xad0 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+0x1a1/0x7a0 drivers/net/wireguard/send.c:276
 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>