syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.5.36/6229 is trying to acquire lock:
ffff888030a81070 (&newdev->mutex){+.+.}-{4:4}, at: uinput_request_send drivers/input/misc/uinput.c:151 [inline]
ffff888030a81070 (&newdev->mutex){+.+.}-{4:4}, at: uinput_request_submit+0x188/0x6f0 drivers/input/misc/uinput.c:182

but task is already holding lock:
ffff88807b3dc8b0 (&ff->mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:228 [inline]
ffff88807b3dc8b0 (&ff->mutex){+.+.}-{4:4}, at: input_ff_upload+0x398/0xb30 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}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:598 [inline]
       __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760
       class_mutex_constructor include/linux/mutex.h:228 [inline]
       input_ff_flush+0x5d/0x170 drivers/input/ff-core.c:231
       input_flush_device+0xb4/0x110 drivers/input/input.c:627
       evdev_release+0xe1/0x800 drivers/input/evdev.c:435
       __fput+0x44c/0xa70 fs/file_table.c:468
       fput_close_sync+0x119/0x200 fs/file_table.c:573
       __do_sys_close fs/open.c:1587 [inline]
       __se_sys_close fs/open.c:1572 [inline]
       __x64_sys_close+0x7f/0x110 fs/open.c:1572
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&dev->mutex#2){+.+.}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:598 [inline]
       __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760
       class_mutex_intr_constructor include/linux/mutex.h:230 [inline]
       input_register_handle+0x18f/0x530 drivers/input/input.c:2653
       kbd_connect+0xc3/0x140 drivers/tty/vt/keyboard.c:1580
       input_attach_handler drivers/input/input.c:993 [inline]
       input_register_device+0xd00/0x1140 drivers/input/input.c:2412
       acpi_button_add+0x6b1/0xb50 drivers/acpi/button.c:621
       acpi_device_probe+0xa8/0x2d0 drivers/acpi/bus.c:1076
       call_driver_probe drivers/base/dd.c:-1 [inline]
       really_probe+0x26d/0x9e0 drivers/base/dd.c:659
       __driver_probe_device+0x18c/0x2f0 drivers/base/dd.c:801
       driver_probe_device+0x4f/0x430 drivers/base/dd.c:831
       __driver_attach+0x452/0x700 drivers/base/dd.c:1217
       bus_for_each_dev+0x233/0x2b0 drivers/base/bus.c:370
       bus_add_driver+0x345/0x640 drivers/base/bus.c:678
       driver_register+0x23a/0x320 drivers/base/driver.c:249
       do_one_initcall+0x236/0x820 init/main.c:1269
       do_initcall_level+0x104/0x190 init/main.c:1331
       do_initcalls+0x59/0xa0 init/main.c:1347
       kernel_init_freeable+0x334/0x4b0 init/main.c:1579
       kernel_init+0x1d/0x1d0 init/main.c:1469
       ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:148
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #1 (input_mutex){+.+.}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:598 [inline]
       __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760
       class_mutex_intr_constructor include/linux/mutex.h:230 [inline]
       input_register_device+0xa76/0x1140 drivers/input/input.c:2408
       uinput_create_device+0x422/0x670 drivers/input/misc/uinput.c:365
       uinput_ioctl_handler+0x3f0/0x1570 drivers/input/misc/uinput.c:918
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:598 [inline]
       __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0x3b0 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+0xb9b/0x2140 kernel/locking/lockdep.c:3908
       __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:598 [inline]
       __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760
       uinput_request_send drivers/input/misc/uinput.c:151 [inline]
       uinput_request_submit+0x188/0x6f0 drivers/input/misc/uinput.c:182
       uinput_dev_upload_effect+0x150/0x1e0 drivers/input/misc/uinput.c:257
       input_ff_upload+0x5fb/0xb30 drivers/input/ff-core.c:148
       evdev_do_ioctl drivers/input/evdev.c:1181 [inline]
       evdev_ioctl_handler+0x1644/0x1f10 drivers/input/evdev.c:1270
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:598 [inline]
       __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0x3b0 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.5.36/6229:
 #0: ffff88802ea9d118 (&evdev->mutex){+.+.}-{4:4}, at: evdev_ioctl_handler+0x121/0x1f10 drivers/input/evdev.c:1261
 #1: ffff88807b3dc8b0 (&ff->mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:228 [inline]
 #1: ffff88807b3dc8b0 (&ff->mutex){+.+.}-{4:4}, at: input_ff_upload+0x398/0xb30 drivers/input/ff-core.c:122

stack backtrace:
CPU: 0 UID: 0 PID: 6229 Comm: syz.5.36 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
 check_noncircular+0x134/0x160 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+0xb9b/0x2140 kernel/locking/lockdep.c:3908
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:598 [inline]
 __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760
 uinput_request_send drivers/input/misc/uinput.c:151 [inline]
 uinput_request_submit+0x188/0x6f0 drivers/input/misc/uinput.c:182
 uinput_dev_upload_effect+0x150/0x1e0 drivers/input/misc/uinput.c:257
 input_ff_upload+0x5fb/0xb30 drivers/input/ff-core.c:148
 evdev_do_ioctl drivers/input/evdev.c:1181 [inline]
 evdev_ioctl_handler+0x1644/0x1f10 drivers/input/evdev.c:1270
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7554d8eec9
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:00007fff16defc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f7554fe5fa0 RCX: 00007f7554d8eec9
RDX: 0000200000000300 RSI: 0000000040304580 RDI: 0000000000000003
RBP: 00007f7554e11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7554fe5fa0 R14: 00007f7554fe5fa0 R15: 0000000000000003
 </TASK>
input: syz1 as /devices/virtual/input/input22