vhci_hcd: disconnect device
BUG: kernel NULL pointer dereference, address: 0000000000000024
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 0 P4D 0 
Oops: 0002 [#1] PREEMPT SMP
CPU: 0 PID: 8 Comm: kworker/u4:0 Not tainted 5.11.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usbip_event event_handler
RIP: 0010:arch_atomic_fetch_add arch/x86/include/asm/atomic.h:184 [inline]
RIP: 0010:atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:143 [inline]
RIP: 0010:__refcount_add include/linux/refcount.h:193 [inline]
RIP: 0010:__refcount_inc include/linux/refcount.h:250 [inline]
RIP: 0010:refcount_inc include/linux/refcount.h:267 [inline]
RIP: 0010:get_task_struct include/linux/sched/task.h:102 [inline]
RIP: 0010:kthread_stop+0x35/0x2d0 kernel/kthread.c:591
Code: 00 65 8b 05 2d 7c e1 7e 83 f8 07 0f 87 2a 02 00 00 89 c0 48 0f a3 05 42 8b 57 04 0f 82 95 01 00 00 4c 8d 63 28 b8 01 00 00 00 <f0> 0f c1 43 28 85 c0 0f 84 eb 01 00 00 0f 88 c1 01 00 00 83 c0 01
RSP: 0018:ffffc90000c97db0 EFLAGS: 00010286
RAX: 0000000000000001 RBX: fffffffffffffffc RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffffffff848f8444 RDI: ffffffff849fda7e
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000050002
R10: ffff888106d91980 R11: ffff888100160800 R12: 0000000000000024
R13: ffff8881426c67a0 R14: dead000000000100 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000024 CR3: 00000001088c6000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 vhci_shutdown_connection+0x6c/0xe0 drivers/usb/usbip/vhci_hcd.c:1023
 event_handler+0xa9/0x180 drivers/usb/usbip/usbip_event.c:78
 process_one_work+0x293/0x610 kernel/workqueue.c:2275
 worker_thread+0x38/0x380 kernel/workqueue.c:2421
 kthread+0x144/0x170 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Modules linked in:
CR2: 0000000000000024
---[ end trace aff08962f2fa3586 ]---
RIP: 0010:arch_atomic_fetch_add arch/x86/include/asm/atomic.h:184 [inline]
RIP: 0010:atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:143 [inline]
RIP: 0010:__refcount_add include/linux/refcount.h:193 [inline]
RIP: 0010:__refcount_inc include/linux/refcount.h:250 [inline]
RIP: 0010:refcount_inc include/linux/refcount.h:267 [inline]
RIP: 0010:get_task_struct include/linux/sched/task.h:102 [inline]
RIP: 0010:kthread_stop+0x35/0x2d0 kernel/kthread.c:591
Code: 00 65 8b 05 2d 7c e1 7e 83 f8 07 0f 87 2a 02 00 00 89 c0 48 0f a3 05 42 8b 57 04 0f 82 95 01 00 00 4c 8d 63 28 b8 01 00 00 00 <f0> 0f c1 43 28 85 c0 0f 84 eb 01 00 00 0f 88 c1 01 00 00 83 c0 01
RSP: 0018:ffffc90000c97db0 EFLAGS: 00010286
RAX: 0000000000000001 RBX: fffffffffffffffc RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffffffff848f8444 RDI: ffffffff849fda7e
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000050002
R10: ffff888106d91980 R11: ffff888100160800 R12: 0000000000000024
R13: ffff8881426c67a0 R14: dead000000000100 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000024 CR3: 00000001088c6000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400