=============================
WARNING: suspicious RCU usage
6.9.0-rc5-syzkaller-01489-gdcc61472534e #0 Not tainted
-----------------------------
net/bridge/br_private.h:1599 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
5 locks held by kworker/1:5/5147:
 #0: ffff888015080948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3229 [inline]
 #0: ffff888015080948 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x8e0/0x17c0 kernel/workqueue.c:3335
 #1: ffffc90003b4fd00 ((work_completion)(&w->work)#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3230 [inline]
 #1: ffffc90003b4fd00 ((work_completion)(&w->work)#2){+.+.}-{0:0}, at: process_scheduled_works+0x91b/0x17c0 kernel/workqueue.c:3335
 #2: ffffffff8f619dc8 (nf_conntrack_mutex){+.+.}-{3:3}, at: nf_ct_iterate_cleanup+0x41/0x4f0 net/netfilter/nf_conntrack_core.c:2405
 #3: ffffc90000a08c00 ((&p->forward_delay_timer)){+.-.}-{0:0}, at: call_timer_fn+0xc0/0x650 kernel/time/timer.c:1790
 #4: ffff888063e64cb8 (&br->lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #4: ffff888063e64cb8 (&br->lock){+.-.}-{2:2}, at: br_forward_delay_timer_expired+0x50/0x440 net/bridge/br_stp_timer.c:86

stack backtrace:
CPU: 1 PID: 5147 Comm: kworker/1:5 Not tainted 6.9.0-rc5-syzkaller-01489-gdcc61472534e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Workqueue: events iterate_cleanup_work
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 lockdep_rcu_suspicious+0x221/0x340 kernel/locking/lockdep.c:6712
 nbp_vlan_group net/bridge/br_private.h:1599 [inline]
 br_mst_set_state+0x1ea/0x650 net/bridge/br_mst.c:105
 br_set_state+0x28a/0x7b0 net/bridge/br_stp.c:47
 br_forward_delay_timer_expired+0x176/0x440 net/bridge/br_stp_timer.c:88
 call_timer_fn+0x18e/0x650 kernel/time/timer.c:1793
 expire_timers kernel/time/timer.c:1844 [inline]
 __run_timers kernel/time/timer.c:2418 [inline]
 __run_timer_base+0x66a/0x8e0 kernel/time/timer.c:2429
 run_timer_base kernel/time/timer.c:2438 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2448
 __do_softirq+0x2c6/0x980 kernel/softirq.c:554
 invoke_softirq kernel/softirq.c:428 [inline]
 __irq_exit_rcu+0xf2/0x1c0 kernel/softirq.c:633
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:645
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1043
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:check_kcov_mode kernel/kcov.c:175 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:236 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x2f/0x90 kernel/kcov.c:311
Code: 8b 04 24 65 48 8b 0c 25 c0 d3 03 00 65 8b 05 80 b2 6d 7e a9 00 01 ff 00 74 10 a9 00 01 00 00 74 57 83 b9 14 16 00 00 00 74 4e <8b> 81 f0 15 00 00 83 f8 03 75 43 48 8b 91 f8 15 00 00 44 8b 89 f4
RSP: 0018:ffffc90003b4fa90 EFLAGS: 00000246
RAX: 0000000080000000 RBX: 0000000000004b61 RCX: ffff88802ac35a00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffff88801dc12d80 R08: ffffffff899c8a40 R09: 1ffffffff25e82b0
R10: dffffc0000000000 R11: fffffbfff25e82b1 R12: ffffc90003b4fb20
R13: 1ffff11003b825b0 R14: dffffc0000000000 R15: ffffc90003b4fb28
 get_next_corpse net/netfilter/nf_conntrack_core.c:2355 [inline]
 nf_ct_iterate_cleanup+0xd0/0x4f0 net/netfilter/nf_conntrack_core.c:2406
 iterate_cleanup_work+0x146/0x260 net/netfilter/nf_nat_masquerade.c:87
 process_one_work kernel/workqueue.c:3254 [inline]
 process_scheduled_works+0xa10/0x17c0 kernel/workqueue.c:3335
 worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
 kthread+0x2f0/0x390 kernel/kthread.c:388
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
bridge0: port 1(bridge_slave_0) entered learning state
bridge0: port 2(bridge_slave_1) entered learning state
----------------
Code disassembly (best guess):
   0:	8b 04 24             	mov    (%rsp),%eax
   3:	65 48 8b 0c 25 c0 d3 	mov    %gs:0x3d3c0,%rcx
   a:	03 00
   c:	65 8b 05 80 b2 6d 7e 	mov    %gs:0x7e6db280(%rip),%eax        # 0x7e6db293
  13:	a9 00 01 ff 00       	test   $0xff0100,%eax
  18:	74 10                	je     0x2a
  1a:	a9 00 01 00 00       	test   $0x100,%eax
  1f:	74 57                	je     0x78
  21:	83 b9 14 16 00 00 00 	cmpl   $0x0,0x1614(%rcx)
  28:	74 4e                	je     0x78
* 2a:	8b 81 f0 15 00 00    	mov    0x15f0(%rcx),%eax <-- trapping instruction
  30:	83 f8 03             	cmp    $0x3,%eax
  33:	75 43                	jne    0x78
  35:	48 8b 91 f8 15 00 00 	mov    0x15f8(%rcx),%rdx
  3c:	44                   	rex.R
  3d:	8b                   	.byte 0x8b
  3e:	89 f4                	mov    %esi,%esp