=============================
WARNING: suspicious RCU usage
5.15.173-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/u4:7/1795:
 #0: ffff0000cde77138 ((wq_completion)wg-kex-wg2){+.+.}-{0:0}, at: process_one_work+0x66c/0x11b8 kernel/workqueue.c:2283
 #1: ffff800024287c00 ((work_completion)(&peer->transmit_handshake_work)){+.+.}-{0:0}, at: process_one_work+0x6ac/0x11b8 kernel/workqueue.c:2285
 #2: ffff0000e80a0ad8 (&peer->endpoint_lock){++-.}-{2:2}, at: wg_socket_send_skb_to_peer+0x64/0x1a8 drivers/net/wireguard/socket.c:173
 #3: ffff800014c92340 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311
 #4: ffff800014c92340 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311
 #5: ffff800014c92340 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311
 #6: ffff0000f1499108 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
 #6: ffff0000f1499108 (&sch->q.lock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3879 [inline]
 #6: ffff0000f1499108 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0x8a0/0x2ac8 net/core/dev.c:4221
 #7: ffff800014c922e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:311

stack backtrace:
CPU: 1 PID: 1795 Comm: kworker/u4:7 Not tainted 5.15.173-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
Workqueue: wg-kex-wg2 wg_packet_handshake_send_worker
Call trace:
 dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 lockdep_rcu_suspicious+0x188/0x1e0 kernel/locking/lockdep.c:6571
 qdisc_lookup+0xc8/0x64c net/sched/sch_api.c:304
 qdisc_tree_reduce_backlog+0x208/0x4a4 net/sched/sch_api.c:800
 sfq_enqueue+0x11e0/0x1ee4
 qdisc_enqueue include/net/sch_generic.h:832 [inline]
 tbf_enqueue+0x2f8/0x5f0 net/sched/sch_tbf.c:237
 dev_qdisc_enqueue+0x60/0x35c net/core/dev.c:3820
 __dev_xmit_skb net/core/dev.c:3904 [inline]
 __dev_queue_xmit+0x1018/0x2ac8 net/core/dev.c:4221
 dev_queue_xmit+0x24/0x34 net/core/dev.c:4289
 neigh_hh_output include/net/neighbour.h:493 [inline]
 neigh_output include/net/neighbour.h:507 [inline]
 ip_finish_output2+0xd3c/0x131c net/ipv4/ip_output.c:228
 __ip_finish_output+0x1b0/0x458
 ip_finish_output+0x40/0x218 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:291 [inline]
 ip_output+0x330/0x49c net/ipv4/ip_output.c:430
 dst_output include/net/dst.h:443 [inline]
 ip_local_out+0x120/0x160 net/ipv4/ip_output.c:126
 iptunnel_xmit+0x40c/0x8fc net/ipv4/ip_tunnel_core.c:82
 udp_tunnel_xmit_skb+0x178/0x284 net/ipv4/udp_tunnel_core.c:175
 send4+0x73c/0xcb0 drivers/net/wireguard/socket.c:85
 wg_socket_send_skb_to_peer+0xc8/0x1a8 drivers/net/wireguard/socket.c:175
 wg_socket_send_buffer_to_peer+0xec/0x144 drivers/net/wireguard/socket.c:200
 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
 wg_packet_handshake_send_worker+0x1a8/0x2a4 drivers/net/wireguard/send.c:51
 process_one_work+0x790/0x11b8 kernel/workqueue.c:2310
 worker_thread+0x910/0x1034 kernel/workqueue.c:2457
 kthread+0x37c/0x45c kernel/kthread.c:334
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870