syzbot

input: Steam Controller as /devices/platform/dummy_hcd.2/usb3/3-1/3-1:0.0/0003:28DE:1102.0008/input/input15
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.248/5717 is trying to acquire lock:
ffffffff8cd3e4e8 (input_mutex){+.+.}-{3:3}, at: input_register_device+0xb66/0x1140 drivers/input/input.c:2422

but task is already holding lock:
ffff888093cedee0 (&hdev->ll_open_lock){+.+.}-{3:3}, at: hid_hw_close+0x2c/0xd0 drivers/hid/hid-core.c:2153

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+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:2127
       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:3616 [inline]
       path_openat+0x2682/0x2f30 fs/namei.c:3750
       do_filp_open+0x1b3/0x3e0 fs/namei.c:3777
       do_sys_openat2+0x142/0x4a0 fs/open.c:1255
       do_sys_open fs/open.c:1271 [inline]
       __do_sys_openat fs/open.c:1287 [inline]
       __se_sys_openat fs/open.c:1282 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1282
       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

-> #1 (&dev->mutex#2){+.+.}-{3:3}:
       __mutex_lock_common+0x1eb/0x2390 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+0x175/0x1e0 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+0x1ee/0x680 init/main.c:1316
       do_initcall_level+0x137/0x1f0 init/main.c:1389
       do_initcalls+0x4b/0x90 init/main.c:1405
       kernel_init_freeable+0x3ce/0x560 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+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_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:2155
       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.2.248/5717:
 #0: ffffffff8d0aeb08 (minors_lock){+.+.}-{3:3}, at: hidraw_release+0x71/0x5d0 drivers/hid/hidraw.c:351
 #1: ffff888093cedee0 (&hdev->ll_open_lock){+.+.}-{3:3}, at: hid_hw_close+0x2c/0xd0 drivers/hid/hid-core.c:2153

stack backtrace:
CPU: 1 PID: 5717 Comm: syz.2.248 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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_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:2155
 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: 0033:0x7f4e24062749
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:00007ffda756f3f8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 000000000001f388 RCX: 00007f4e24062749
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f4e242bada0 R08: 0000000000000001 R09: 00000014a756f6ef
R10: 0000001b31220000 R11: 0000000000000246 R12: 00007f4e242b8fac
R13: 00007f4e242b8fa0 R14: ffffffffffffffff R15: 00007ffda756f510
 </TASK>