syzbot

general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
CPU: 0 PID: 5946 Comm: syz.0.18 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:pcl818_ai_cancel+0x69/0x3f0 drivers/comedi/drivers/pcl818.c:762
Code: 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 e9 cb df f9 48 8b 03 48 89 04 24 49 83 c4 28 4c 89 e0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 e7 e8 c8 cb df f9 4d 8b 24 24 48 83 c3
RSP: 0018:ffffc9000472fa80 EFLAGS: 00010206
RAX: 0000000000000005 RBX: ffff8880779e3500 RCX: ffff88807a04da00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88802b53f800
RBP: 0000000000000001 R08: ffff88802b53f92f R09: 1ffff110056a7f25
R10: dffffc0000000000 R11: ffffed10056a7f26 R12: 0000000000000028
R13: dffffc0000000000 R14: ffff88802b53f800 R15: dffffc0000000000
FS:  000055557483a500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2d363fff CR3: 00000000779d6000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 pcl818_detach+0x66/0xd0 drivers/comedi/drivers/pcl818.c:1115
 comedi_device_detach_locked+0x172/0x710 drivers/comedi/drivers.c:206
 do_devconfig_ioctl drivers/comedi/comedi_fops.c:848 [inline]
 comedi_unlocked_ioctl+0xccc/0xfe0 drivers/comedi/comedi_fops.c:2178
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7cb438eec9
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:00007ffd2e120998 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f7cb45e5fa0 RCX: 00007f7cb438eec9
RDX: 0000000000000000 RSI: 0000000040946400 RDI: 0000000000000003
RBP: 00007f7cb4411f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7cb45e5fa0 R14: 00007f7cb45e5fa0 R15: 0000000000000003
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:pcl818_ai_cancel+0x69/0x3f0 drivers/comedi/drivers/pcl818.c:762
Code: 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 e9 cb df f9 48 8b 03 48 89 04 24 49 83 c4 28 4c 89 e0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 e7 e8 c8 cb df f9 4d 8b 24 24 48 83 c3
RSP: 0018:ffffc9000472fa80 EFLAGS: 00010206
RAX: 0000000000000005 RBX: ffff8880779e3500 RCX: ffff88807a04da00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88802b53f800
RBP: 0000000000000001 R08: ffff88802b53f92f R09: 1ffff110056a7f25
R10: dffffc0000000000 R11: ffffed10056a7f26 R12: 0000000000000028
R13: dffffc0000000000 R14: ffff88802b53f800 R15: dffffc0000000000
FS:  000055557483a500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c008396000 CR3: 00000000779d6000 CR4: 00000000003506e0
----------------
Code disassembly (best guess):
   0:	8b 1b                	mov    (%rbx),%ebx
   2:	48 89 d8             	mov    %rbx,%rax
   5:	48 c1 e8 03          	shr    $0x3,%rax
   9:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1)
   e:	74 08                	je     0x18
  10:	48 89 df             	mov    %rbx,%rdi
  13:	e8 e9 cb df f9       	call   0xf9dfcc01
  18:	48 8b 03             	mov    (%rbx),%rax
  1b:	48 89 04 24          	mov    %rax,(%rsp)
  1f:	49 83 c4 28          	add    $0x28,%r12
  23:	4c 89 e0             	mov    %r12,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 e7             	mov    %r12,%rdi
  34:	e8 c8 cb df f9       	call   0xf9dfcc01
  39:	4d 8b 24 24          	mov    (%r12),%r12
  3d:	48                   	rex.W
  3e:	83                   	.byte 0x83
  3f:	c3                   	ret