vhci_hcd: disconnect device
vhci_hcd vhci_hcd.0: pdev(5) rhport(0) sockfd(4)
vhci_hcd vhci_hcd.0: devid(0) speed(3) speed_str(high-speed)
vhci_hcd vhci_hcd.0: port 1 already used
==================================================================
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:558
Write of size 4 at addr 000000000000001c by task kworker/u4:0/7

CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 4.19.160-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/0x2fe lib/dump_stack.c:118
 kasan_report_error.cold+0x15b/0x1c7 mm/kasan/report.c:352
vhci_hcd vhci_hcd.0: port 1 already used
 kasan_report+0x8f/0x96 mm/kasan/report.c:412
 atomic_inc include/asm-generic/atomic-instrumented.h:109 [inline]
 kthread_stop+0x72/0x6b0 kernel/kthread.c:558
 vhci_shutdown_connection+0x14e/0x280 drivers/usb/usbip/vhci_hcd.c:1021
 event_handler+0x1f0/0x4f0 drivers/usb/usbip/usbip_event.c:78
 process_one_work+0x864/0x1570 kernel/workqueue.c:2155
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2298
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
==================================================================
vhci_hcd: connection closed
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 7 Comm: kworker/u4:0 Tainted: G    B             4.19.160-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/0x2fe lib/dump_stack.c:118
vhci_hcd vhci_hcd.0: pdev(0) rhport(0) sockfd(4)
 panic+0x26a/0x50e kernel/panic.c:186
vhci_hcd vhci_hcd.0: devid(0) speed(3) speed_str(high-speed)
 kasan_end_report+0x43/0x49 mm/kasan/report.c:180
 kasan_report_error.cold+0xa7/0x1c7 mm/kasan/report.c:359
usb 19-2: new high-speed USB device number 3 using vhci_hcd
 kasan_report+0x8f/0x96 mm/kasan/report.c:412
 atomic_inc include/asm-generic/atomic-instrumented.h:109 [inline]
 kthread_stop+0x72/0x6b0 kernel/kthread.c:558
 vhci_shutdown_connection+0x14e/0x280 drivers/usb/usbip/vhci_hcd.c:1021
 event_handler+0x1f0/0x4f0 drivers/usb/usbip/usbip_event.c:78
 process_one_work+0x864/0x1570 kernel/workqueue.c:2155
vhci_hcd vhci_hcd.0: pdev(4) rhport(0) sockfd(4)
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2298
vhci_hcd vhci_hcd.0: devid(0) speed(3) speed_str(high-speed)
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
vhci_hcd vhci_hcd.0: pdev(2) rhport(1) sockfd(4)
vhci_hcd vhci_hcd.0: devid(0) speed(3) speed_str(high-speed)
Kernel Offset: disabled
Rebooting in 86400 seconds..