syzbot

=============================
WARNING: suspicious RCU usage
5.15.179-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/0:0/7:
 #0: ffff88807db1a138 ((wq_completion)wg-crypt-wg0){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90000cc7d20 ((work_completion)(&peer->transmit_packet_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff888077928ad8 (&peer->endpoint_lock){++..}-{2:2}, at: wg_socket_send_skb_to_peer+0x56/0x1d0 drivers/net/wireguard/socket.c:173
 #3: ffffffff8cb1f540 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
 #4: ffffffff8cb1f540 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
 #5: ffffffff8cb1f540 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
 #6: ffff888027b9d908 (&sch->q.lock){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
 #6: ffff888027b9d908 (&sch->q.lock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3910 [inline]
 #6: ffff888027b9d908 (&sch->q.lock){+...}-{2:2}, at: __dev_queue_xmit+0xc1f/0x32b0 net/core/dev.c:4252
 #7: ffffffff8cb1f4e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311

stack backtrace:
CPU: 0 PID: 7 Comm: kworker/0:0 Not tainted 5.15.179-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
 sfq_enqueue+0x1214/0x23e0 net/sched/sch_sfq.c:475
 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:3851
 __dev_xmit_skb net/core/dev.c:3935 [inline]
 __dev_queue_xmit+0xe32/0x32b0 net/core/dev.c:4252
 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+0x536/0x970 net/ipv6/ip6_udp_tunnel.c:109
 send6+0x6b8/0xad0 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