syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.3.20/6096 is trying to acquire lock:
ffff88814e4fe870 (&newdev->mutex){+.+.}-{4:4}, at: uinput_request_send drivers/input/misc/uinput.c:151 [inline]
ffff88814e4fe870 (&newdev->mutex){+.+.}-{4:4}, at: uinput_request_submit+0x1bd/0x740 drivers/input/misc/uinput.c:182

but task is already holding lock:
ffff88814e4fa0b0 (&ff->mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
ffff88814e4fa0b0 (&ff->mutex){+.+.}-{4:4}, at: input_ff_upload+0x398/0xb80 drivers/input/ff-core.c:122

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&ff->mutex){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       class_mutex_constructor include/linux/mutex.h:253 [inline]
       input_ff_flush+0x5e/0x1a0 drivers/input/ff-core.c:231
       input_flush_device+0xd6/0x130 drivers/input/input.c:628
       evdev_release+0xe1/0x800 drivers/input/evdev.c:435
       __fput+0x44f/0xa70 fs/file_table.c:468
       fput_close_sync+0x11f/0x240 fs/file_table.c:573
       __do_sys_close fs/open.c:1573 [inline]
       __se_sys_close fs/open.c:1558 [inline]
       __x64_sys_close+0x7e/0x110 fs/open.c:1558
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&dev->mutex#2){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       class_mutex_intr_constructor include/linux/mutex.h:255 [inline]
       input_register_handle+0x18d/0x540 drivers/input/input.c:2619
       kbd_connect+0xbe/0x150 drivers/tty/vt/keyboard.c:1559
       input_attach_handler drivers/input/input.c:994 [inline]
       input_register_device+0xd00/0x1160 drivers/input/input.c:2378
       acpi_button_add+0x6b9/0xb70 drivers/acpi/button.c:621
       acpi_device_probe+0xa8/0x320 drivers/acpi/bus.c:1076
       call_driver_probe drivers/base/dd.c:-1 [inline]
       really_probe+0x267/0xaf0 drivers/base/dd.c:661
       __driver_probe_device+0x18c/0x320 drivers/base/dd.c:803
       driver_probe_device+0x4f/0x240 drivers/base/dd.c:833
       __driver_attach+0x349/0x640 drivers/base/dd.c:1227
       bus_for_each_dev+0x23b/0x2c0 drivers/base/bus.c:383
       bus_add_driver+0x345/0x670 drivers/base/bus.c:715
       driver_register+0x23a/0x320 drivers/base/driver.c:249
       do_one_initcall+0x250/0x840 init/main.c:1378
       do_initcall_level+0x104/0x190 init/main.c:1440
       do_initcalls+0x59/0xa0 init/main.c:1456
       kernel_init_freeable+0x2a6/0x3d0 init/main.c:1688
       kernel_init+0x1d/0x1d0 init/main.c:1578
       ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

-> #1 (input_mutex){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       class_mutex_intr_constructor include/linux/mutex.h:255 [inline]
       input_register_device+0xa76/0x1160 drivers/input/input.c:2374
       uinput_create_device+0x422/0x670 drivers/input/misc/uinput.c:365
       uinput_ioctl_handler+0x417/0x14a0 drivers/input/misc/uinput.c:919
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:597 [inline]
       __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&newdev->mutex){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
       lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       uinput_request_send drivers/input/misc/uinput.c:151 [inline]
       uinput_request_submit+0x1bd/0x740 drivers/input/misc/uinput.c:182
       uinput_dev_upload_effect+0x182/0x230 drivers/input/misc/uinput.c:257
       input_ff_upload+0x5fb/0xb80 drivers/input/ff-core.c:148
       evdev_do_ioctl drivers/input/evdev.c:1181 [inline]
       evdev_ioctl_handler+0x16e2/0x1fe0 drivers/input/evdev.c:1270
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:597 [inline]
       __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &newdev->mutex --> &dev->mutex#2 --> &ff->mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ff->mutex);
                               lock(&dev->mutex#2);
                               lock(&ff->mutex);
  lock(&newdev->mutex);

 *** DEADLOCK ***

2 locks held by syz.3.20/6096:
 #0: ffff88802f8a7118 (&evdev->mutex){+.+.}-{4:4}, at: evdev_ioctl_handler+0x14a/0x1fe0 drivers/input/evdev.c:1261
 #1: ffff88814e4fa0b0 (&ff->mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
 #1: ffff88814e4fa0b0 (&ff->mutex){+.+.}-{4:4}, at: input_ff_upload+0x398/0xb80 drivers/input/ff-core.c:122

stack backtrace:
CPU: 0 UID: 0 PID: 6096 Comm: syz.3.20 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043
 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:614 [inline]
 __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
 uinput_request_send drivers/input/misc/uinput.c:151 [inline]
 uinput_request_submit+0x1bd/0x740 drivers/input/misc/uinput.c:182
 uinput_dev_upload_effect+0x182/0x230 drivers/input/misc/uinput.c:257
 input_ff_upload+0x5fb/0xb80 drivers/input/ff-core.c:148
 evdev_do_ioctl drivers/input/evdev.c:1181 [inline]
 evdev_ioctl_handler+0x16e2/0x1fe0 drivers/input/evdev.c:1270
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa9f7b9aeb9
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:00007ffd2c3bb878 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fa9f7e15fa0 RCX: 00007fa9f7b9aeb9
RDX: 0000200000000300 RSI: 0000000040304580 RDI: 0000000000000004
RBP: 00007fa9f7c08c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa9f7e15fac R14: 00007fa9f7e15fa0 R15: 00007fa9f7e15fa0
 </TASK>