Oops: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
CPU: 1 UID: 0 PID: 1638 Comm: syz.9.3770 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:kernfs_root+0xcb/0x230
Code: c0 42 9c 8b be 4b 03 00 00 48 c7 c2 00 43 9c 8b e8 da 4b 40 ff 49 bc 00 00 00 00 00 fc ff df 4d 8d 7e 30 4c 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 ff e8 96 da c5 ff 4d 8b 3f e8 ee 44 1c
RSP: 0018:ffffc900029ffa28 EFLAGS: 00010207
RAX: 0000000000000005 RBX: ffffffff825d392c RCX: ffff888049fa3980
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1020008383 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffffffffffff R15: 000000000000002f
FS:  00007f2b053736c0(0000) GS:ffff8881a3c1b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000930000 CR3: 0000000123230000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 kernfs_remove_by_name_ns+0x2b/0x130
 bus_remove_driver+0x198/0x2f0
 comedi_device_detach_locked+0x178/0x750
 comedi_unlocked_ioctl+0xcde/0x1020
 __se_sys_ioctl+0xfc/0x170
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2b0458ebe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2b05373038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f2b047b5fa0 RCX: 00007f2b0458ebe9
RDX: 0000000000000000 RSI: 0000000040946400 RDI: 0000000000000015
RBP: 00007f2b04611e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2b047b6038 R14: 00007f2b047b5fa0 R15: 00007ffd0444a198
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:kernfs_root+0xcb/0x230
Code: c0 42 9c 8b be 4b 03 00 00 48 c7 c2 00 43 9c 8b e8 da 4b 40 ff 49 bc 00 00 00 00 00 fc ff df 4d 8d 7e 30 4c 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 ff e8 96 da c5 ff 4d 8b 3f e8 ee 44 1c
RSP: 0018:ffffc900029ffa28 EFLAGS: 00010207
RAX: 0000000000000005 RBX: ffffffff825d392c RCX: ffff888049fa3980
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1020008383 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffffffffffff R15: 000000000000002f
FS:  00007f2b053736c0(0000) GS:ffff8881a3c1b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000932000 CR3: 0000000123230000 CR4: 00000000000006f0
