=============================
WARNING: suspicious RCU usage
5.15.185-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
4 locks held by syz.5.180/4968:
 #0: ffffffff8c11bfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
 #1: ffff888074145948 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: net_tx_action+0x6bc/0x870 net/core/dev.c:5128
 #2: ffff888074145908 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
 #2: ffff888074145908 (&sch->q.lock){+.-.}-{2:2}, at: sch_direct_xmit+0x305/0x4a0 net/sched/sch_generic.c:354
 #3: ffffffff8c11bfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311

stack backtrace:
CPU: 1 PID: 4968 Comm: syz.5.180 Not tainted 5.15.185-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 qdisc_lookup+0xa6/0x650 net/sched/sch_api.c:304
 qdisc_tree_reduce_backlog+0x213/0x4e0 net/sched/sch_api.c:800
 cake_dequeue+0x1b8f/0x4aa0 net/sched/sch_cake.c:2189
 qdisc_peek_dequeued+0x6e/0x1f0 include/net/sch_generic.h:1115
 tbf_dequeue+0x7d/0xce0 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+0x237/0x1480 net/sched/sch_generic.c:415
 qdisc_run+0x103/0x2f0 include/net/pkt_sched.h:132
 net_tx_action+0x6bc/0x870 net/core/dev.c:5128
 handle_softirqs+0x328/0x820 kernel/softirq.c:576
 do_softirq+0x13b/0x200 kernel/softirq.c:477
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x174/0x1b0 kernel/softirq.c:401
 spin_unlock_bh include/linux/spinlock.h:408 [inline]
 htable_selective_cleanup+0x286/0x320 net/netfilter/xt_hashlimit.c:374
 htable_put+0x1e9/0x240 net/netfilter/xt_hashlimit.c:430
 cleanup_match net/ipv6/netfilter/ip6_tables.c:479 [inline]
 cleanup_entry+0x136/0x310 net/ipv6/netfilter/ip6_tables.c:663
 translate_table+0x1e3c/0x2020 net/ipv6/netfilter/ip6_tables.c:746
 do_replace net/ipv6/netfilter/ip6_tables.c:1156 [inline]
 do_ip6t_set_ctl+0x975/0xd00 net/ipv6/netfilter/ip6_tables.c:1646
 nf_setsockopt+0x25f/0x280 net/netfilter/nf_sockopt.c:101
 ipv6_setsockopt+0x1cb8/0x3890 net/ipv6/ipv6_sockglue.c:1014
 rawv6_setsockopt+0x263/0x620 net/ipv6/raw.c:1089
 __sys_setsockopt+0x3d6/0x5e0 net/socket.c:2203
 __do_sys_setsockopt net/socket.c:2214 [inline]
 __se_sys_setsockopt net/socket.c:2211 [inline]
 __x64_sys_setsockopt+0xb1/0xc0 net/socket.c:2211
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fb0fb444929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb0f92ac038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007fb0fb66bfa0 RCX: 00007fb0fb444929
RDX: 0000000000000040 RSI: 0000000000000029 RDI: 0000000000000004
RBP: 00007fb0fb4c6b39 R08: 00000000000004c0 R09: 0000000000000000
R10: 00002000000004c0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb0fb66bfa0 R15: 00007ffd7314d578
 </TASK>