Oops: general protection fault, probably for non-canonical address 0xdffffc000000000e: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000070-0x0000000000000077]
CPU: 1 UID: 0 PID: 17973 Comm: syz.3.3311 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:kernfs_root+0xb5/0x2a0 fs/kernfs/kernfs-internal.h:79
Code: f5 00 00 00 e8 6c 23 59 ff 48 85 db 48 0f 44 dd e8 60 23 59 ff 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 78 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 d6 01 00 00 48 8b 6b 78 e8 e8 92 fa 08 31 ff 89
RSP: 0018:ffffc90004107758 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: ffffffffffffffff RCX: ffffc900316cc000
RDX: 000000000000000e RSI: ffffffff82633430 RDI: 0000000000000077
RBP: ffff88804b5a1028 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000002 R15: ffff888027293120
FS:  0000000000000000(0000) GS:ffff88809790d000(0063) knlGS:00000000f53d5b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000339f3ffc CR3: 000000005213b000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 kernfs_remove_by_name_ns+0x2e/0x110 fs/kernfs/dir.c:1711
 sysfs_remove_file include/linux/sysfs.h:770 [inline]
 driver_remove_file drivers/base/driver.c:201 [inline]
 driver_remove_file+0x4a/0x60 drivers/base/driver.c:197
 remove_bind_files drivers/base/bus.c:605 [inline]
 bus_remove_driver+0x224/0x2c0 drivers/base/bus.c:743
 driver_unregister+0x76/0xb0 drivers/base/driver.c:277
 comedi_device_detach_locked+0x12f/0xa50 drivers/comedi/drivers.c:207
 do_devconfig_ioctl+0x555/0x710 drivers/comedi/comedi_fops.c:848
 comedi_unlocked_ioctl+0x165d/0x2f00 drivers/comedi/comedi_fops.c:2178
 comedi_compat_ioctl+0x1d0/0x990 drivers/comedi/comedi_fops.c:3249
 __do_compat_sys_ioctl fs/ioctl.c:695 [inline]
 __se_compat_sys_ioctl fs/ioctl.c:638 [inline]
 __ia32_compat_sys_ioctl+0x242/0x370 fs/ioctl.c:638
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0x7c/0x300 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7f02579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f53d555c EFLAGS: 00000296 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000040946400
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:kernfs_root+0xb5/0x2a0 fs/kernfs/kernfs-internal.h:79
Code: f5 00 00 00 e8 6c 23 59 ff 48 85 db 48 0f 44 dd e8 60 23 59 ff 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 78 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 d6 01 00 00 48 8b 6b 78 e8 e8 92 fa 08 31 ff 89
RSP: 0018:ffffc90004107758 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: ffffffffffffffff RCX: ffffc900316cc000
RDX: 000000000000000e RSI: ffffffff82633430 RDI: 0000000000000077
RBP: ffff88804b5a1028 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000002 R15: ffff888027293120
FS:  0000000000000000(0000) GS:ffff88809780d000(0063) knlGS:00000000f53d5b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f72c0bb4 CR3: 000000005213b000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	f5                   	cmc
   1:	00 00                	add    %al,(%rax)
   3:	00 e8                	add    %ch,%al
   5:	6c                   	insb   (%dx),%es:(%rdi)
   6:	23 59 ff             	and    -0x1(%rcx),%ebx
   9:	48 85 db             	test   %rbx,%rbx
   c:	48 0f 44 dd          	cmove  %rbp,%rbx
  10:	e8 60 23 59 ff       	call   0xff592375
  15:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  1c:	fc ff df
  1f:	48 8d 7b 78          	lea    0x78(%rbx),%rdi
  23:	48 89 fa             	mov    %rdi,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2e:	0f 85 d6 01 00 00    	jne    0x20a
  34:	48 8b 6b 78          	mov    0x78(%rbx),%rbp
  38:	e8 e8 92 fa 08       	call   0x8fa9325
  3d:	31 ff                	xor    %edi,%edi
  3f:	89                   	.byte 0x89