[moderation] [usb?] KCSAN: data-race in event_handler / usbip_stop_eh

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c21bb4193868 Merge tag 'for_linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=160a2bb9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=84b3039e8461eef5
dashboard link: https://syzkaller.appspot.com/bug?extid=88552062c8fe23ce80d1
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [gre...@linuxfoundation.org i...@zenithal.me linux-...@vger.kernel.org linu...@vger.kernel.org sh...@kernel.org valentin...@gmail.com]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d4fbf8fa3d0b/disk-c21bb419.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6a0ac310e2fa/vmlinux-c21bb419.xz
kernel image: https://storage.googleapis.com/syzbot-assets/751285db76d1/bzImage-c21bb419.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+885520...@syzkaller.appspotmail.com

EXT4-fs (loop1): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
==================================================================
BUG: KCSAN: data-race in event_handler / usbip_stop_eh

read-write to 0xffff8881038bfc08 of 8 bytes by task 113 on cpu 1:
unset_event drivers/usb/usbip/usbip_event.c:36 [inline]
event_handler+0x1a8/0x330 drivers/usb/usbip/usbip_event.c:80
process_one_work kernel/workqueue.c:3322 [inline]
process_scheduled_works+0x4d4/0x9a0 kernel/workqueue.c:3405
worker_thread+0x569/0x750 kernel/workqueue.c:3486
kthread+0x221/0x270 kernel/kthread.c:436
ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff8881038bfc08 of 8 bytes by task 4936 on cpu 0:
usbip_stop_eh+0x37/0x120 drivers/usb/usbip/usbip_event.c:118
vgadget_pullup+0x16a/0x1a0 drivers/usb/usbip/vudc_dev.c:183
usb_gadget_disconnect_locked+0xc9/0x220 drivers/usb/gadget/udc/core.c:785
gadget_unbind_driver+0x65/0x210 drivers/usb/gadget/udc/core.c:1718
device_remove drivers/base/dd.c:616 [inline]
__device_release_driver drivers/base/dd.c:1349 [inline]
device_release_driver_internal+0x2c7/0x520 drivers/base/dd.c:1372
driver_detach+0x167/0x1f0 drivers/base/dd.c:1435
bus_remove_driver+0x197/0x1d0 drivers/base/bus.c:832
driver_unregister+0x4e/0x80 drivers/base/driver.c:202
usb_gadget_unregister_driver+0x33/0x60 drivers/usb/gadget/udc/core.c:1784
unregister_gadget drivers/usb/gadget/configfs.c:263 [inline]
gadget_dev_desc_UDC_store+0x115/0x1f0 drivers/usb/gadget/configfs.c:290
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x1cb/0x250 fs/configfs/file.c:229
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x57d/0x990 fs/read_write.c:687
ksys_write+0xdc/0x1a0 fs/read_write.c:739
__do_sys_write fs/read_write.c:750 [inline]
__se_sys_write fs/read_write.c:747 [inline]
__x64_sys_write+0x40/0x50 fs/read_write.c:747
x64_sys_call+0x27e1/0x3020 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000007 -> 0x0000000000000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4936 Comm: syz.1.434 Tainted: G W syzkaller #0 PREEMPT(lazy)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup