EXT4-fs (loop1): mounted filesystem without journal. Opts: ,errors=continue. Quota mode: none.
=============================
WARNING: suspicious RCU usage
5.15.169-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
6 locks held by syz.1.9/4154:
 #0: ffff0000c1208960 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1678 [inline]
 #0: ffff0000c1208960 (sk_lock-AF_INET){+.+.}-{0:0}, at: sctp_sendmsg+0x8fc/0x2844 net/sctp/socket.c:1970
 #1: ffff800014c822e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311
 #2: ffff800014c82340 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311
 #3: ffff800014c82340 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311
 #4: ffff0000d9931108 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
 #4: ffff0000d9931108 (&sch->q.lock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3875 [inline]
 #4: ffff0000d9931108 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0x8a0/0x2ac8 net/core/dev.c:4217
 #5: ffff800014c822e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:311

stack backtrace:
CPU: 0 PID: 4154 Comm: syz.1.9 Not tainted 5.15.169-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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+0x200/0x4e8 net/sched/sch_api.c:800
 pfifo_tail_enqueue+0x280/0x38c net/sched/sch_fifo.c:51
 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:3816
 __dev_xmit_skb net/core/dev.c:3900 [inline]
 __dev_queue_xmit+0x1018/0x2ac8 net/core/dev.c:4217
 dev_queue_xmit+0x24/0x34 net/core/dev.c:4285
 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 net/ipv4/ip_output.c:126 [inline]
 __ip_queue_xmit+0xe90/0x1a04 net/ipv4/ip_output.c:532
 sctp_v4_xmit+0x430/0xb00 net/sctp/protocol.c:1071
 sctp_packet_transmit+0x1ec0/0x237c net/sctp/output.c:652
 sctp_packet_singleton+0x1d4/0x2c0 net/sctp/outqueue.c:780
 sctp_outq_flush_ctrl net/sctp/outqueue.c:911 [inline]
 sctp_outq_flush+0x528/0x2e84 net/sctp/outqueue.c:1209
 sctp_outq_uncork+0x84/0xc0 net/sctp/outqueue.c:761
 sctp_side_effects net/sctp/sm_sideeffect.c:1199 [inline]
 sctp_do_sm+0x485c/0x4e80 net/sctp/sm_sideeffect.c:1170
 sctp_primitive_ASSOCIATE+0x98/0xc8 net/sctp/primitive.c:73
 sctp_sendmsg_to_asoc+0xf78/0x1854 net/sctp/socket.c:1841
 sctp_sendmsg+0x196c/0x2844 net/sctp/socket.c:2031
 inet_sendmsg+0x15c/0x290 net/ipv4/af_inet.c:836
 sock_sendmsg_nosec net/socket.c:704 [inline]
 __sock_sendmsg net/socket.c:716 [inline]
 __sys_sendto+0x388/0x4d0 net/socket.c:2063
 __do_sys_sendto net/socket.c:2075 [inline]
 __se_sys_sendto net/socket.c:2071 [inline]
 __arm64_sys_sendto+0xd8/0xf8 net/socket.c:2071
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584