vhci_hcd vhci_hcd.0: port 1 already used
vhci_hcd: disconnect device
vhci_hcd vhci_hcd.0: pdev(0) rhport(0) sockfd(5)
vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed)
vhci_hcd vhci_hcd.0: pdev(2) rhport(0) sockfd(5)
BUG: unable to handle kernel NULL pointer dereference at 000000000000001c
vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed)
IP: atomic_inc arch/x86/include/asm/atomic.h:92 [inline]
IP: kthread_stop+0x47/0x640 kernel/kthread.c:525
PGD a1b52067 P4D a1b52067 PUD a0091067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 9391 Comm: kworker/u4:7 Not tainted 4.14.210-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usbip_event event_handler
task: ffff88808f226400 task.stack: ffff88809ea10000
RIP: 0010:atomic_inc arch/x86/include/asm/atomic.h:92 [inline]
RIP: 0010:kthread_stop+0x47/0x640 kernel/kthread.c:525
RSP: 0018:ffff88809ea17c70 EFLAGS: 00010297
RAX: ffff88808f226400 RBX: 0000000000000001 RCX: 0000000000000000
vhci_hcd vhci_hcd.0: pdev(1) rhport(0) sockfd(5)
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: 0000000000000286
vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed)
RBP: fffffffffffffffc R08: ffffffff8b994d40 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888237d34a58
vhci_hcd vhci_hcd.0: pdev(5) rhport(0) sockfd(5)
R13: ffff888237d34a48 R14: fffffbfff1924130 R15: ffffffff89857e40
vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed)
FS:  0000000000000000(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000
vhci_hcd: connection closed
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000001c CR3: 000000009f1e8000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 vhci_shutdown_connection+0x12a/0x240 drivers/usb/usbip/vhci_hcd.c:1035
vhci_hcd: connection closed
 event_handler+0x1c3/0x4a0 drivers/usb/usbip/usbip_event.c:92
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: 00 65 8b 1d bc 17 c9 7e 83 fb 07 
vhci_hcd vhci_hcd.0: pdev(3) rhport(1) sockfd(5)
0f 
vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed)
87 
vhci_hcd: connection closed
5b 04 00 00 e8 be d5 1e 00 89 db 48 0f a3 1d 0c 42 d0 08 0f 82 a2 03 00 00 e8 a9 d5 1e 00 <f0> ff 45 20 48 8d 7d 24 48 b8 00 00 00 00 00 fc ff df 48 89 fa 
RIP: atomic_inc arch/x86/include/asm/atomic.h:92 [inline] RSP: ffff88809ea17c70
RIP: kthread_stop+0x47/0x640 kernel/kthread.c:525 RSP: ffff88809ea17c70
CR2: 000000000000001c
vhci_hcd vhci_hcd.0: pdev(4) rhport(1) sockfd(5)
---[ end trace a4989fc142648c4b ]---
vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed)