vhci_hcd: connection closed
==================================================================
BUG: KASAN: null-ptr-deref in atomic_inc include/asm-generic/atomic-instrumented.h:109 [inline]
BUG: KASAN: null-ptr-deref in kthread_stop+0x72/0x6b0 kernel/kthread.c:583
Write of size 4 at addr 000000000000001c by task kworker/u4:6/9439

CPU: 1 PID: 9439 Comm: kworker/u4:6 Not tainted 4.19.178-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usbip_event event_handler
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
 kasan_report_error.cold+0x15b/0x1b9 mm/kasan/report.c:352
 kasan_report+0x8f/0xa0 mm/kasan/report.c:412
 atomic_inc include/asm-generic/atomic-instrumented.h:109 [inline]
 kthread_stop+0x72/0x6b0 kernel/kthread.c:583
 vhci_shutdown_connection+0x14e/0x280 drivers/usb/usbip/vhci_hcd.c:1023
 event_handler+0x1f0/0x4f0 drivers/usb/usbip/usbip_event.c:78
 process_one_work+0x864/0x1570 kernel/workqueue.c:2152
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2295
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
==================================================================
vhci_hcd: vhci_device speed not set
EXT4-fs (loop3): mounted filesystem without journal. Opts: ,errors=continue
usb 11-1: new full-speed USB device number 2 using vhci_hcd