possible deadlock in __input_unregister_device

Status: auto-obsoleted due to no activity on 2025/08/18 04:46
Reported-by: syzbot+4bb3bcf1da5385e36785@syzkaller.appspotmail.com
First crash: 515d, last: 450d
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 possible deadlock in __input_unregister_device (2) 4 8 192d 218d 0/3 auto-obsoleted due to no activity on 2026/05/03 13:11
linux-6.1 possible deadlock in __input_unregister_device (2) 4 1 65d 65d 0/3 upstream: reported on 2026/05/30 21:57
linux-6.1 possible deadlock in __input_unregister_device 4 1 515d 515d 0/3 auto-obsoleted due to no activity on 2025/06/14 09:26
upstream possible deadlock in __input_unregister_device input 4 289 532d 722d 0/29 auto-obsoleted due to no activity on 2025/04/28 01:51

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
5.15.182-syzkaller #0 Not tainted
------------------------------------------------------
syz.0.2376/13866 is trying to acquire lock:
ffff8880223522c0 (&dev->mutex#2){+.+.}-{3:3}, at: input_disconnect_device drivers/input/input.c:748 [inline]
ffff8880223522c0 (&dev->mutex#2){+.+.}-{3:3}, at: __input_unregister_device+0x2e/0x320 drivers/input/input.c:2278

but task is already holding lock:
ffff88801ee99ee0 (&hdev->ll_open_lock){+.+.}-{3:3}, at: hid_hw_open+0x23/0x160 drivers/hid/hid-core.c:2118

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&hdev->ll_open_lock){+.+.}-{3:3}:
       __mutex_lock_common+0x1eb/0x2390 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:2118
       input_open_device+0x16c/0x2e0 drivers/input/input.c:640
       mousedev_open_device+0xc3/0x150 drivers/input/mousedev.c:430
       mousedev_open+0x2e5/0x4a0 drivers/input/mousedev.c:556
       chrdev_open+0x597/0x670 fs/char_dev.c:414
       do_dentry_open+0x7ff/0xf80 fs/open.c:826
       do_open fs/namei.c:3608 [inline]
       path_openat+0x2682/0x2f30 fs/namei.c:3742
       do_filp_open+0x1b3/0x3e0 fs/namei.c:3769
       do_sys_openat2+0x142/0x4a0 fs/open.c:1253
       do_sys_open fs/open.c:1269 [inline]
       __do_sys_openat fs/open.c:1285 [inline]
       __se_sys_openat fs/open.c:1280 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1280
       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

-> #0 (&dev->mutex#2){+.+.}-{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+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
       lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       input_disconnect_device drivers/input/input.c:748 [inline]
       __input_unregister_device+0x2e/0x320 drivers/input/input.c:2278
       input_unregister_device+0x97/0xf0 drivers/input/input.c:2473
       steam_client_ll_open+0x73/0x90 drivers/hid/hid-steam.c:640
       hid_hw_open+0xdd/0x160 drivers/hid/hid-core.c:2123
       hidraw_open+0x28f/0x8b0 drivers/hid/hidraw.c:289
       chrdev_open+0x597/0x670 fs/char_dev.c:414
       do_dentry_open+0x7ff/0xf80 fs/open.c:826
       do_open fs/namei.c:3608 [inline]
       path_openat+0x2682/0x2f30 fs/namei.c:3742
       do_filp_open+0x1b3/0x3e0 fs/namei.c:3769
       do_sys_openat2+0x142/0x4a0 fs/open.c:1253
       do_sys_open fs/open.c:1269 [inline]
       __do_sys_openat fs/open.c:1285 [inline]
       __se_sys_openat fs/open.c:1280 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1280
       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

other info that might help us debug this:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

2 locks held by syz.0.2376/13866:
 #0: ffffffff8d0acc28 (minors_lock){+.+.}-{3:3}, at: hidraw_open+0x91/0x8b0 drivers/hid/hidraw.c:275
 #1: ffff88801ee99ee0 (&hdev->ll_open_lock){+.+.}-{3:3}, at: hid_hw_open+0x23/0x160 drivers/hid/hid-core.c:2118

stack backtrace:
CPU: 0 PID: 13866 Comm: syz.0.2376 Not tainted 5.15.182-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 check_noncircular+0x274/0x310 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+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 input_disconnect_device drivers/input/input.c:748 [inline]
 __input_unregister_device+0x2e/0x320 drivers/input/input.c:2278
 input_unregister_device+0x97/0xf0 drivers/input/input.c:2473
 steam_client_ll_open+0x73/0x90 drivers/hid/hid-steam.c:640
 hid_hw_open+0xdd/0x160 drivers/hid/hid-core.c:2123
 hidraw_open+0x28f/0x8b0 drivers/hid/hidraw.c:289
 chrdev_open+0x597/0x670 fs/char_dev.c:414
 do_dentry_open+0x7ff/0xf80 fs/open.c:826
 do_open fs/namei.c:3608 [inline]
 path_openat+0x2682/0x2f30 fs/namei.c:3742
 do_filp_open+0x1b3/0x3e0 fs/namei.c:3769
 do_sys_openat2+0x142/0x4a0 fs/open.c:1253
 do_sys_open fs/open.c:1269 [inline]
 __do_sys_openat fs/open.c:1285 [inline]
 __se_sys_openat fs/open.c:1280 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1280
 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: 0033:0x7f41c31de2d0
Code: 48 89 44 24 20 75 93 44 89 54 24 0c e8 49 94 02 00 44 8b 54 24 0c 89 da 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 38 44 89 c7 89 44 24 0c e8 9c 94 02 00 8b 44
RSP: 002b:00007f41c1025b70 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f41c31de2d0
RDX: 0000000000000002 RSI: 00007f41c1025c10 RDI: 00000000ffffff9c
RBP: 00007f41c1025c10 R08: 0000000000000000 R09: 0023776172646968
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f41c3407080 R15: 00007ffc8af809e8
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/10 04:45 linux-5.15.y 3b8db0e4f263 77908e5f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __input_unregister_device
2025/03/06 06:51 linux-5.15.y c16c81c81336 831e3629 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __input_unregister_device
* Struck through repros no longer work on HEAD.