syzbot

INFO: task udevd:4349 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D
 stack:27056 pid: 4349 ppid:  3560 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xcfc/0x2400 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 device_lock include/linux/device.h:764 [inline]
 uevent_show+0x17a/0x330 drivers/base/core.c:2408
 dev_attr_show+0x50/0xb0 drivers/base/core.c:2110
 sysfs_kf_seq_show+0x316/0x4c0 fs/sysfs/file.c:61
 seq_read_iter+0x49b/0xd50 fs/seq_file.c:230
 call_read_iter include/linux/fs.h:2167 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0x759/0xd60 fs/read_write.c:485
 ksys_read+0x152/0x260 fs/read_write.c:623
 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: 0033:0x7f51c591c407
RSP: 002b:00007fffc27640a0 EFLAGS: 00000202
 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f51c582e880 RCX: 00007f51c591c407
RDX: 0000000000001000 RSI: 00005583f12ba200 RDI: 0000000000000008
RBP: 00007f51c5a64ff0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000000a
R13: 00007f51c5a64ea0 R14: 0000000000000000 R15: 00005583f123b8a0
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/u4:0/9:
 #0: ffff888016c79138
 (
(wq_completion)events_unbound
){+.+.}-{0:0}
, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: 
ffffc90000ce7d00
 (
(reaper_work).work
){+.+.}-{0:0}
, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
1 lock held by khungtaskd/27:
 #0: 
ffffffff8c31eb20
 (
rcu_read_lock
){....}-{1:2}
, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3946:
 #0: 
ffff88814d459098
 (
&tty->ldisc_sem
){++++}-{0:0}
, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: 
ffffc900026562e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5df/0x1a70 drivers/tty/n_tty.c:2158
2 locks held by kworker/u4:3/4243:
 #0: 
ffff888016c79138
 (
(wq_completion)events_unbound
){+.+.}-{0:0}
, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: 
ffffc90002edfd00
 (
connector_reaper_work
){+.+.}-{0:0}
, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
9 locks held by kworker/0:3/4304:
4 locks held by udevd/4349:
 #0: ffff888022b70790 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xad/0xd50 fs/seq_file.c:182
 #1: ffff88801bf66c88
 (
&of->mutex
){+.+.}-{3:3}
, at: kernfs_seq_start+0x51/0x3c0 fs/kernfs/file.c:112
 #2: 
ffff88807436c1d8 (kn->active#32){++++}-{0:0}
, at: kernfs_seq_start+0x71/0x3c0 fs/kernfs/file.c:113
 #3: 
ffff88807cea5220
 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
 (&dev->mutex){....}-{3:3}, at: uevent_show+0x17a/0x330 drivers/base/core.c:2408
2 locks held by dhcpcd/4393:
 #0: 
ffff888024e36120
 (
sk_lock-AF_PACKET
){+.+.}-{0:0}
, at: lock_sock include/net/sock.h:1744 [inline]
, at: packet_do_bind+0x35/0xda0 net/packet/af_packet.c:3213
 #1: 
ffffffff8c3235a8
 (
rcu_state.exp_mutex
){+.+.}-{3:3}
, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
, at: synchronize_rcu_expedited+0x2d1/0x750 kernel/rcu/tree_exp.h:845
2 locks held by dhcpcd/4395:
 #0: 
ffff88801ecac120
 (
sk_lock-AF_PACKET
){+.+.}-{0:0}
, at: lock_sock include/net/sock.h:1744 [inline]
, at: packet_do_bind+0x35/0xda0 net/packet/af_packet.c:3213
 #1: 
ffffffff8c3235a8
 (
rcu_state.exp_mutex
){+.+.}-{3:3}
, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
, at: synchronize_rcu_expedited+0x3a5/0x750 kernel/rcu/tree_exp.h:845
1 lock held by dhcpcd/4396:
 #0: ffff88807be66120 (sk_lock-AF_PACKET
){+.+.}-{0:0}
, at: lock_sock include/net/sock.h:1744 [inline]
, at: packet_do_bind+0x35/0xda0 net/packet/af_packet.c:3213
1 lock held by dhcpcd/4397:
 #0: 
ffff888024a50120
 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1744 [inline]
 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x35/0xda0 net/packet/af_packet.c:3213

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe0f/0xe50 kernel/hung_task.c:369
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4304 Comm: kworker/0:3 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: usb_hub_wq hub_event
RIP: 0010:uart_console_write+0x1/0x100 drivers/tty/serial/serial_core.c:1975
Code: 89 f1 80 e1 07 80 c1 03 38 c1 7c c5 4c 89 f7 e8 45 e5 70 fd eb bb 89 d9 80 e1 07 38 c1 7c bf 48 89 df e8 62 e5 70 fd eb b5 55 <41> 57 41 56 41 55 41 54 53 48 83 ec 10 48 89 4c 24 08 41 89 d4 49
RSP: 0018:ffffc9000315e0d0 EFLAGS: 00000093
RAX: ffffffff844fb869 RBX: ffffffff96602840 RCX: ffffffff844fbc40
RDX: 000000000000002b RSI: ffffffff9631e980 RDI: ffffffff96602840
RBP: ffffc9000315e290 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200062bbf8 R12: 0000000000000000
R13: 1ffff9200062bc30 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f465edb1f40 CR3: 000000002ab5d000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 serial8250_console_write+0xc46/0x1000 drivers/tty/serial/8250/8250_port.c:3392
 call_console_drivers kernel/printk/printk.c:-1 [inline]
 console_unlock+0xb9a/0x1120 kernel/printk/printk.c:2744
 vprintk_emit+0xc0/0x150 kernel/printk/printk.c:2274
 dev_vprintk_emit+0x2e1/0x380 drivers/base/core.c:4638
 dev_printk_emit+0xeb/0x140 drivers/base/core.c:4649
 _dev_err+0x11b/0x170 drivers/base/core.c:4704
 parse_uac2_sample_rate_range+0x992/0xc60 sound/usb/format.c:401
 parse_audio_format_rates_v2v3+0x3c7/0x16c0 sound/usb/format.c:636
 parse_audio_format_ii sound/usb/format.c:778 [inline]
 snd_usb_parse_audio_format+0x4ae/0x740 sound/usb/format.c:799
 snd_usb_get_audioformat_uac12 sound/usb/stream.c:854 [inline]
 __snd_usb_parse_audio_interface+0x18b1/0x4b00 sound/usb/stream.c:1196
 snd_usb_parse_audio_interface+0x36/0xb0 sound/usb/stream.c:1274
 create_standard_audio_quirk+0x59/0x120 sound/usb/quirks.c:100
 snd_usb_create_quirk sound/usb/quirks.c:577 [inline]
 create_composite_quirk+0x1ec/0x4e0 sound/usb/quirks.c:48
 usb_audio_probe+0xb97/0x1d90 sound/usb/card.c:885
 usb_probe_interface+0x5c5/0xb20 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x284/0xc80 drivers/base/dd.c:595
 __driver_probe_device+0x18c/0x330 drivers/base/dd.c:755
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:785
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:907
 bus_for_each_drv+0x184/0x210 drivers/base/bus.c:429
 __device_attach+0x2a8/0x480 drivers/base/dd.c:979
 bus_probe_device+0xbc/0x1e0 drivers/base/bus.c:489
 device_add+0xa00/0xfb0 drivers/base/core.c:3412
 usb_set_configuration+0x1991/0x1fd0 drivers/usb/core/message.c:2223
 usb_generic_driver_probe+0x89/0x150 drivers/usb/core/generic.c:238
 usb_probe_device+0x139/0x270 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x284/0xc80 drivers/base/dd.c:595
 __driver_probe_device+0x18c/0x330 drivers/base/dd.c:755
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:785
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:907
 bus_for_each_drv+0x184/0x210 drivers/base/bus.c:429
 __device_attach+0x2a8/0x480 drivers/base/dd.c:979
 bus_probe_device+0xbc/0x1e0 drivers/base/bus.c:489
 device_add+0xa00/0xfb0 drivers/base/core.c:3412
 usb_new_device+0xd65/0x1660 drivers/usb/core/hub.c:2632
 hub_port_connect drivers/usb/core/hub.c:5497 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5637 [inline]
 port_event drivers/usb/core/hub.c:5799 [inline]
 hub_event+0x2e4a/0x55e0 drivers/usb/core/hub.c:5881
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>