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: 4463 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+0x65/0x3e0 drivers/comedi/drivers/pcl818.c:764
Code: 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 bd ed 49 fa 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 9c ed 49 fa 4d 8b 24 24 48 83 c3
RSP: 0018:ffffc90004937a80 EFLAGS: 00010206
RAX: 0000000000000005 RBX: ffff888021dc6680 RCX: ffff8880740d9dc0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88814c63f800
RBP: 0000000000000001 R08: dffffc0000000000 R09: ffffed10298c7f26
R10: ffffed10298c7f26 R11: 1ffff110298c7f25 R12: 0000000000000028
R13: dffffc0000000000 R14: ffff88814c63f800 R15: dffffc0000000000
FS:  000055556d772500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f56a26305f0 CR3: 000000001e572000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 pcl818_detach+0x62/0xd0 drivers/comedi/drivers/pcl818.c:1117
 comedi_device_detach_locked+0x16e/0x710 drivers/comedi/drivers.c:207
 do_devconfig_ioctl drivers/comedi/comedi_fops.c:844 [inline]
 comedi_unlocked_ioctl+0xd0b/0x1050 drivers/comedi/comedi_fops.c:2173
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f56a2756ba9
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:00007ffd9ac3e768 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f56a299dfa0 RCX: 00007f56a2756ba9
RDX: 0000000000000000 RSI: 0000000040946400 RDI: 0000000000000003
RBP: 00007f56a27d9e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f56a299dfa0 R14: 00007f56a299dfa0 R15: 0000000000000003
 </TASK>
Modules linked in:
---[ end trace f55780b1d4c95d7d ]---
RIP: 0010:pcl818_ai_cancel+0x65/0x3e0 drivers/comedi/drivers/pcl818.c:764
Code: 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 bd ed 49 fa 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 9c ed 49 fa 4d 8b 24 24 48 83 c3
RSP: 0018:ffffc90004937a80 EFLAGS: 00010206
RAX: 0000000000000005 RBX: ffff888021dc6680 RCX: ffff8880740d9dc0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88814c63f800
RBP: 0000000000000001 R08: dffffc0000000000 R09: ffffed10298c7f26
R10: ffffed10298c7f26 R11: 1ffff110298c7f25 R12: 0000000000000028
R13: dffffc0000000000 R14: ffff88814c63f800 R15: dffffc0000000000
FS:  000055556d772500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c006b24000 CR3: 000000001e572000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
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 bd ed 49 fa       	call   0xfa49edd5
  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 9c ed 49 fa       	call   0xfa49edd5
  39:	4d 8b 24 24          	mov    (%r12),%r12
  3d:	48                   	rex.W
  3e:	83                   	.byte 0x83
  3f:	c3                   	ret