[syzbot] [input?] possible deadlock in input_ff_flush

syzbot
2025-01-05T12:40:20Z

Hello,

syzbot found the following issue on:

HEAD commit: ccb98ccef0e5 Merge tag 'platform-drivers-x86-v6.13-4' of g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1613fac4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=dc863cc90857c683
dashboard link: https://syzkaller.appspot.com/bug?extid=ed7c6209f62eba1565aa
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17bd56df980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-ccb98cce.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1f85617cae1e/vmlinux-ccb98cce.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0dc4d6c6c931/bzImage-ccb98cce.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ed7c6209f62eba1565aa@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.13.0-rc5-syzkaller-00004-gccb98ccef0e5 #0 Not tainted
------------------------------------------------------
udevd/5941 is trying to acquire lock:
ffff8880293600b0 (&ff->mutex){+.+.}-{4:4}, at: input_ff_flush+0x63/0x170 drivers/input/ff-core.c:242

but task is already holding lock:
ffff88804d45b2c0 (&dev->mutex#2){+.+.}-{4:4}, at: input_flush_device+0x4b/0xd0 drivers/input/input.c:647

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #3 (&dev->mutex#2){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/mutex.c:585 [inline]
__mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
input_register_handle+0xca/0x5e0 drivers/input/input.c:2725
kbd_connect+0xca/0x160 drivers/tty/vt/keyboard.c:1587
input_attach_handler.isra.0+0x181/0x260 drivers/input/input.c:1032
input_register_device+0xa84/0x1110 drivers/input/input.c:2475
acpi_button_add+0x57a/0xb70 drivers/acpi/button.c:615
acpi_device_probe+0xc6/0x330 drivers/acpi/bus.c:1076
call_driver_probe drivers/base/dd.c:579 [inline]
really_probe+0x23e/0xa90 drivers/base/dd.c:658
__driver_probe_device+0x1de/0x440 drivers/base/dd.c:800
driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:830
__driver_attach+0x283/0x580 drivers/base/dd.c:1216
bus_for_each_dev+0x13c/0x1d0 drivers/base/bus.c:370
bus_add_driver+0x2e9/0x690 drivers/base/bus.c:675
driver_register+0x15c/0x4b0 drivers/base/driver.c:246
__acpi_bus_register_driver+0xdf/0x130 drivers/acpi/bus.c:1027
acpi_button_register_driver drivers/acpi/button.c:745 [inline]
acpi_button_driver_init+0x82/0x110 drivers/acpi/button.c:754
do_one_initcall+0x128/0x700 init/main.c:1266
do_initcall_level init/main.c:1328 [inline]
do_initcalls init/main.c:1344 [inline]
do_basic_setup init/main.c:1363 [inline]
kernel_init_freeable+0x5c7/0x900 init/main.c:1577
kernel_init+0x1c/0x2b0 init/main.c:1466
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #2 (input_mutex){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/mutex.c:585 [inline]
__mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
input_register_device+0x98a/0x1110 drivers/input/input.c:2468
uinput_create_device drivers/input/misc/uinput.c:365 [inline]
uinput_ioctl_handler.isra.0+0x130c/0x1d70 drivers/input/misc/uinput.c:918
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl fs/ioctl.c:892 [inline]
__x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&newdev->mutex){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/mutex.c:585 [inline]
__mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
uinput_request_send drivers/input/misc/uinput.c:151 [inline]
uinput_request_submit.part.0+0x25/0x2e0 drivers/input/misc/uinput.c:182
uinput_request_submit drivers/input/misc/uinput.c:179 [inline]
uinput_dev_upload_effect+0x175/0x1f0 drivers/input/misc/uinput.c:257
input_ff_upload+0x55b/0xbf0 drivers/input/ff-core.c:152
evdev_do_ioctl+0xf45/0x1ae0 drivers/input/evdev.c:1181
evdev_ioctl_handler drivers/input/evdev.c:1270 [inline]
evdev_ioctl+0x16a/0x1a0 drivers/input/evdev.c:1279
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl fs/ioctl.c:892 [inline]
__x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&ff->mutex){+.+.}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3161 [inline]
check_prevs_add kernel/locking/lockdep.c:3280 [inline]
validate_chain kernel/locking/lockdep.c:3904 [inline]
__lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226
lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849
__mutex_lock_common kernel/locking/mutex.c:585 [inline]
__mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
input_ff_flush+0x63/0x170 drivers/input/ff-core.c:242
uinput_dev_flush+0x2a/0x40 drivers/input/misc/uinput.c:283
input_flush_device+0x97/0xd0 drivers/input/input.c:652
evdev_release+0x33d/0x400 drivers/input/evdev.c:435
__fput+0x3f8/0xb60 fs/file_table.c:450
__fput_sync+0xa1/0xc0 fs/file_table.c:535
__do_sys_close fs/open.c:1554 [inline]
__se_sys_close fs/open.c:1539 [inline]
__x64_sys_close+0x86/0x100 fs/open.c:1539
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

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

Possible unsafe locking scenario:

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

*** DEADLOCK ***

2 locks held by udevd/5941:
#0: ffff888024d58118 (&evdev->mutex){+.+.}-{4:4}, at: evdev_release+0x77/0x400 drivers/input/evdev.c:432
#1: ffff88804d45b2c0 (&dev->mutex#2){+.+.}-{4:4}, at: input_flush_device+0x4b/0xd0 drivers/input/input.c:647

stack backtrace:
CPU: 2 UID: 0 PID: 5941 Comm: udevd Not tainted 6.13.0-rc5-syzkaller-00004-gccb98ccef0e5 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
print_circular_bug+0x419/0x5d0 kernel/locking/lockdep.c:2074
check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2206
check_prev_add kernel/locking/lockdep.c:3161 [inline]
check_prevs_add kernel/locking/lockdep.c:3280 [inline]
validate_chain kernel/locking/lockdep.c:3904 [inline]
__lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226
lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849
__mutex_lock_common kernel/locking/mutex.c:585 [inline]
__mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
input_ff_flush+0x63/0x170 drivers/input/ff-core.c:242
uinput_dev_flush+0x2a/0x40 drivers/input/misc/uinput.c:283
input_flush_device+0x97/0xd0 drivers/input/input.c:652
evdev_release+0x33d/0x400 drivers/input/evdev.c:435
__fput+0x3f8/0xb60 fs/file_table.c:450
__fput_sync+0xa1/0xc0 fs/file_table.c:535
__do_sys_close fs/open.c:1554 [inline]
__se_sys_close fs/open.c:1539 [inline]
__x64_sys_close+0x86/0x100 fs/open.c:1539
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1d757850a8
Code: 48 8b 05 83 9d 0d 00 64 c7 00 16 00 00 00 83 c8 ff 48 83 c4 20 5b c3 64 8b 04 25 18 00 00 00 85 c0 75 20 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 5b 48 8b 15 51 9d 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007fffb61bcef8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 00007f1d756b10e0 RCX: 00007f1d757850a8
RDX: fffffffffffffe60 RSI: 0000000080184540 RDI: 0000000000000008
RBP: 00005620d7ea5160 R08: 00000000ffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000016
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>

---
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