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possible deadlock in input_register_device (4)

Status: upstream: reported on 2026/05/14 15:22
Reported-by: syzbot+84d01e7883b798244618@syzkaller.appspotmail.com
First crash: 6d07h, last: 5d10h
▶ ▼ Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in input_register_device 4 5 434d 440d 0/3 auto-obsoleted due to no activity on 2025/06/20 09:48
linux-6.1 possible deadlock in input_register_device (3) 4 1 6d07h 6d07h 0/3 upstream: reported on 2026/05/14 15:13
linux-6.1 possible deadlock in input_register_device (2) 4 1 151d 151d 0/3 auto-obsoleted due to no activity on 2026/03/30 14:59
linux-5.15 possible deadlock in input_register_device 4 3 430d 440d 0/3 auto-obsoleted due to no activity on 2025/06/24 16:34
linux-5.15 possible deadlock in input_register_device (2) 4 2 247d 295d 0/3 auto-obsoleted due to no activity on 2025/12/24 16:08
linux-5.15 possible deadlock in input_register_device (3) 4 2 131d 135d 0/3 auto-obsoleted due to no activity on 2026/04/19 03:54

Sample crash report:
input: Steam Controller as /devices/platform/dummy_hcd.0/usb1/1-1/1-1:0.0/0003:28DE:1102.000C/input/input19
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.884/9488 is trying to acquire lock:
ffffffff8cf465e8 (input_mutex){+.+.}-{3:3}, at: input_register_device+0xb66/0x1140 drivers/input/input.c:2422

but task is already holding lock:
ffff88805b4adee0 (&hdev->ll_open_lock){+.+.}-{3:3}, at: hid_hw_close+0x2c/0xd0 drivers/hid/hid-core.c:2158

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&hdev->ll_open_lock){+.+.}-{3:3}:
       __mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_killable_nested+0x17/0x20 kernel/locking/mutex.c:758
       hid_hw_open+0x23/0x160 drivers/hid/hid-core.c:2132
       input_open_device+0x16c/0x2e0 drivers/input/input.c:640
       kbd_connect+0xe9/0x130 drivers/tty/vt/keyboard.c:1581
       input_attach_handler drivers/input/input.c:1046 [inline]
       input_register_device+0xda7/0x1140 drivers/input/input.c:2429
       hidinput_connect+0x2440/0x2d90 drivers/hid/hid-input.c:2046
       hid_connect+0x46a/0xe10 drivers/hid/hid-core.c:1988
       hid_hw_start+0x99/0x100 drivers/hid/hid-core.c:2095
       hid_device_probe+0x2ea/0x360 drivers/hid/hid-core.c:2327
       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
       hid_add_device+0x389/0x530 drivers/hid/hid-core.c:2475
       usbhid_probe+0xb92/0xf40 drivers/hid/usbhid/hid-core.c:1442
       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

-> #1 (&dev->mutex#2){+.+.}-{3:3}:
       __mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_interruptible_nested+0x17/0x20 kernel/locking/mutex.c:765
       input_register_handle+0x67/0x3a0 drivers/input/input.c:2588
       kbd_connect+0xbf/0x130 drivers/tty/vt/keyboard.c:1577
       input_attach_handler drivers/input/input.c:1046 [inline]
       input_register_device+0xda7/0x1140 drivers/input/input.c:2429
       acpi_button_add+0x6ba/0xae0 drivers/acpi/button.c:579
       acpi_device_probe+0xa3/0x300 drivers/acpi/bus.c:1013
       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
       __driver_attach+0x46b/0x670 drivers/base/dd.c:1164
       bus_for_each_dev+0x182/0x1f0 drivers/base/bus.c:303
       bus_add_driver+0x30a/0x5a0 drivers/base/bus.c:620
       driver_register+0x32d/0x430 drivers/base/driver.c:240
       do_one_initcall+0x272/0x730 init/main.c:1316
       do_initcall_level+0x137/0x1f0 init/main.c:1389
       do_initcalls+0x4b/0x90 init/main.c:1405
       kernel_init_freeable+0x3e9/0x570 init/main.c:1629
       kernel_init+0x19/0x1b0 init/main.c:1520
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #0 (input_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c42/0x7d10 kernel/locking/lockdep.c:5012
       lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_interruptible_nested+0x17/0x20 kernel/locking/mutex.c:765
       input_register_device+0xb66/0x1140 drivers/input/input.c:2422
       steam_input_register+0x9b1/0xc80 drivers/hid/hid-steam.c:469
       hid_hw_close+0xa5/0xd0 drivers/hid/hid-core.c:2160
       drop_ref drivers/hid/hidraw.c:338 [inline]
       hidraw_release+0x39d/0x5d0 drivers/hid/hidraw.c:360
       __fput+0x234/0x930 fs/file_table.c:311
       task_work_run+0x125/0x1a0 kernel/task_work.c:188
       tracehook_notify_resume include/linux/tracehook.h:189 [inline]
       exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
       exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
       __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
       syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
       do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
  input_mutex --> &dev->mutex#2 --> &hdev->ll_open_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&hdev->ll_open_lock);
                               lock(&dev->mutex#2);
                               lock(&hdev->ll_open_lock);
  lock(input_mutex);

 *** DEADLOCK ***

2 locks held by syz.0.884/9488:
 #0: ffffffff8d2b6f48 (minors_lock){+.+.}-{3:3}, at: hidraw_release+0x71/0x5d0 drivers/hid/hidraw.c:351
 #1: ffff88805b4adee0 (&hdev->ll_open_lock){+.+.}-{3:3}, at: hid_hw_close+0x2c/0xd0 drivers/hid/hid-core.c:2158

stack backtrace:
CPU: 0 PID: 9488 Comm: syz.0.884 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
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c42/0x7d10 kernel/locking/lockdep.c:5012
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_interruptible_nested+0x17/0x20 kernel/locking/mutex.c:765
 input_register_device+0xb66/0x1140 drivers/input/input.c:2422
 steam_input_register+0x9b1/0xc80 drivers/hid/hid-steam.c:469
 hid_hw_close+0xa5/0xd0 drivers/hid/hid-core.c:2160
 drop_ref drivers/hid/hidraw.c:338 [inline]
 hidraw_release+0x39d/0x5d0 drivers/hid/hidraw.c:360
 __fput+0x234/0x930 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f539ad3ee59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffeb7af8db8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f539afb9da0 RCX: 00007f539ad3ee59
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f539afb9da0 R08: 0000000000000006 R09: 0000000000000000
R10: 00000000003ffcb8 R11: 0000000000000246 R12: 000000000004c5f4
R13: 00007f539afb7fac R14: 000000000004ba15 R15: 00007ffeb7af8ec0
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/15 12:25 linux-5.15.y de8dfb3f0278 9cd3beaa .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in input_register_device
2026/05/14 15:21 linux-5.15.y de8dfb3f0278 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in input_register_device
* Struck through repros no longer work on HEAD.