vhci_hcd: release socket
vhci_hcd: disconnect device
vhci_hcd vhci_hcd.0: pdev(0) rhport(0) sockfd(3)
vhci_hcd: connection closed
vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed)
BUG: unable to handle kernel NULL pointer dereference at 000000000000001c
IP: atomic_inc arch/x86/include/asm/atomic.h:92 [inline]
IP: kthread_stop+0x47/0x640 kernel/kthread.c:525
PGD af722067 P4D af722067 PUD a54bd067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 2848 Comm: kworker/u4:4 Not tainted 4.14.212-syzkaller #0
vhci_hcd vhci_hcd.0: pdev(2) rhport(0) sockfd(3)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed)
Workqueue: usbip_event event_handler
task: ffff8880ac6f4540 task.stack: ffff8880ac708000
vhci_hcd vhci_hcd.0: port 1 already used
RIP: 0010:atomic_inc arch/x86/include/asm/atomic.h:92 [inline]
RIP: 0010:kthread_stop+0x47/0x640 kernel/kthread.c:525
RSP: 0018:ffff8880ac70fc70 EFLAGS: 00010297
RAX: ffff8880ac6f4540 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: 0000000000000286
RBP: fffffffffffffffc R08: ffffffff8b9952e8 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880aa0f0bd8
R13: ffff8880aa0f0bc8 R14: fffffbfff1924130 R15: ffffffff89857f80
FS:  0000000000000000(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000001c CR3: 000000009ea8d000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
vhci_hcd: connection closed
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 vhci_shutdown_connection+0x12a/0x240 drivers/usb/usbip/vhci_hcd.c:1035
 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
vhci_hcd vhci_hcd.0: port 1 already used
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: 
vhci_hcd: connection closed
00 65 8b 1d bc 17 c9 7e 83 fb 07 0f 87 5b 04 00 00 e8 be d5 1e 00 89 db 48 0f a3 1d 0c 44 d0 08 0f 82 a2 03 00 00 e8 a9 d5 1e 00 <f0> 
vhci_hcd: vhci_device speed not set
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: ffff8880ac70fc70
RIP: kthread_stop+0x47/0x640 kernel/kthread.c:525 RSP: ffff8880ac70fc70
usb 13-2: new full-speed USB device number 2 using vhci_hcd
CR2: 000000000000001c
---[ end trace 77bb53f7e88d7ba4 ]---