syzbot

input: syz0 as /devices/virtual/input/input5
======================================================
WARNING: possible circular locking dependency detected
6.14.0-rc5-syzkaller-00137-g00a7d39898c8 #0 Not tainted
------------------------------------------------------
syz-executor228/5834 is trying to acquire lock:
ffff888028755070 (&newdev->mutex){+.+.}-{4:4}, at: uinput_request_send drivers/input/misc/uinput.c:151 [inline]
ffff888028755070 (&newdev->mutex){+.+.}-{4:4}, at: uinput_request_submit+0x19c/0x740 drivers/input/misc/uinput.c:182

but task is already holding lock:
ffff8880287510b0 (&ff->mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:201 [inline]
ffff8880287510b0 (&ff->mutex){+.+.}-{4:4}, at: input_ff_upload+0x3ea/0xb20 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+0x1ed/0x550 kernel/locking/lockdep.c:5851
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730
       class_mutex_constructor include/linux/mutex.h:201 [inline]
       input_ff_flush+0x5e/0x150 drivers/input/ff-core.c:231
       input_flush_device+0xb2/0xe0 drivers/input/input.c:627
       evdev_release+0xf6/0x7d0 drivers/input/evdev.c:435
       __fput+0x3e9/0x9f0 fs/file_table.c:464
       __do_sys_close fs/open.c:1580 [inline]
       __se_sys_close fs/open.c:1565 [inline]
       __x64_sys_close+0x7f/0x110 fs/open.c:1565
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&dev->mutex#2){+.+.}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730
       class_mutex_intr_constructor include/linux/mutex.h:203 [inline]
       input_register_handle+0x1a5/0x500 drivers/input/input.c:2653
       kbd_connect+0xbf/0x130 drivers/tty/vt/keyboard.c:1587
       input_attach_handler drivers/input/input.c:993 [inline]
       input_register_device+0xce2/0x10c0 drivers/input/input.c:2412
       acpi_button_add+0x6c6/0xb90 drivers/acpi/button.c:615
       acpi_device_probe+0xa5/0x2b0 drivers/acpi/bus.c:1076
       really_probe+0x2b9/0xad0 drivers/base/dd.c:658
       __driver_probe_device+0x1a2/0x390 drivers/base/dd.c:800
       driver_probe_device+0x50/0x430 drivers/base/dd.c:830
       __driver_attach+0x45f/0x710 drivers/base/dd.c:1216
       bus_for_each_dev+0x239/0x2b0 drivers/base/bus.c:370
       bus_add_driver+0x346/0x670 drivers/base/bus.c:678
       driver_register+0x23a/0x320 drivers/base/driver.c:249
       do_one_initcall+0x248/0x930 init/main.c:1257
       do_initcall_level+0x157/0x210 init/main.c:1319
       do_initcalls+0x71/0xd0 init/main.c:1335
       kernel_init_freeable+0x435/0x5d0 init/main.c:1568
       kernel_init+0x1d/0x2b0 init/main.c:1457
       ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #1 (input_mutex){+.+.}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730
       class_mutex_intr_constructor include/linux/mutex.h:203 [inline]
       input_register_device+0xa8f/0x10c0 drivers/input/input.c:2408
       uinput_create_device+0x40e/0x630 drivers/input/misc/uinput.c:365
       uinput_ioctl_handler+0x488/0x1770 drivers/input/misc/uinput.c:918
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&newdev->mutex){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3163 [inline]
       check_prevs_add kernel/locking/lockdep.c:3282 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
       __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730
       uinput_request_send drivers/input/misc/uinput.c:151 [inline]
       uinput_request_submit+0x19c/0x740 drivers/input/misc/uinput.c:182
       uinput_dev_upload_effect+0x199/0x240 drivers/input/misc/uinput.c:257
       input_ff_upload+0x5ef/0xb20 drivers/input/ff-core.c:148
       evdev_do_ioctl drivers/input/evdev.c:1181 [inline]
       evdev_ioctl_handler+0x17c7/0x21b0 drivers/input/evdev.c:1270
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       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-executor228/5834:
 #0: ffff888147aef118 (&evdev->mutex){+.+.}-{4:4}, at: evdev_ioctl_handler+0x122/0x21b0 drivers/input/evdev.c:1261
 #1: ffff8880287510b0 (&ff->mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:201 [inline]
 #1: ffff8880287510b0 (&ff->mutex){+.+.}-{4:4}, at: input_ff_upload+0x3ea/0xb20 drivers/input/ff-core.c:122

stack backtrace:
CPU: 0 UID: 0 PID: 5834 Comm: syz-executor228 Not tainted 6.14.0-rc5-syzkaller-00137-g00a7d39898c8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2076
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2208
 check_prev_add kernel/locking/lockdep.c:3163 [inline]
 check_prevs_add kernel/locking/lockdep.c:3282 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
 __mutex_lock_common kernel/locking/mutex.c:585 [inline]
 __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730
 uinput_request_send drivers/input/misc/uinput.c:151 [inline]
 uinput_request_submit+0x19c/0x740 drivers/input/misc/uinput.c:182
 uinput_dev_upload_effect+0x199/0x240 drivers/input/misc/uinput.c:257
 input_ff_upload+0x5ef/0xb20 drivers/input/ff-core.c:148
 evdev_do_ioctl drivers/input/evdev.c:1181 [inline]
 evdev_ioctl_handler+0x17c7/0x21b0 drivers/input/evdev.c:1270
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4f94b1c2a9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4f94ad4218 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f4f94ba3328 RCX: 00007f4f94b1c2a9
RDX: 0000400000000180 RSI: 0000000040304580 RDI: 0000000000000004
RBP: 00007f4f94ba3320 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4f94b70074
R13: 0000400000000280 R14: 00004000000000c0 R15: 0000400000000180
 </TASK>