syzbot


divide error in comedi_inc_scan_progress (2)

Status: upstream: reported on 2026/02/27 16:53
Reported-by: syzbot+d754c7b8e146c62520df@syzkaller.appspotmail.com
First crash: 10d, last: 10d
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 divide error in comedi_inc_scan_progress (2) 2 7 4d09h 124d 0/2 upstream: reported on 2025/11/05 08:13
linux-6.6 divide error in comedi_inc_scan_progress 2 2 228d 230d 0/2 auto-obsoleted due to no activity on 2025/11/01 16:46
upstream divide error in comedi_inc_scan_progress comedi 2 74 93d 244d 0/29 auto-obsoleted due to no activity on 2026/02/15 00:02
linux-5.15 divide error in comedi_inc_scan_progress 2 2 111d 111d 0/3 auto-obsoleted due to no activity on 2026/02/27 00:49
linux-6.1 divide error in comedi_inc_scan_progress 2 2 38d 89d 0/3 upstream: reported on 2025/12/10 08:43

Sample crash report:
divide error: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 11046 Comm: syz.5.2037 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:comedi_inc_scan_progress+0x19e/0x430 drivers/comedi/drivers.c:563
Code: b6 0c 19 84 c9 0f 85 b8 01 00 00 03 45 34 4c 8d a5 88 00 00 00 4c 89 e1 48 c1 e9 03 0f b6 0c 19 84 c9 0f 85 c7 01 00 00 31 d2 <41> f7 34 24 41 89 17 45 89 ec eb 0f e8 01 de f5 f9 48 bb 00 00 00
RSP: 0018:ffffc90000007c80 EFLAGS: 00010046
RAX: 0000000000000001 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8880782c4200 R08: ffff8880782c4200 R09: 1ffff9200095f200
R10: dffffc0000000000 R11: fffff5200095f201 R12: ffff8880782c4288
R13: 0000000000000002 R14: 0000000000000000 R15: ffff8880782c4234
FS:  00007fd6dbd5d6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c32cb3b CR3: 000000002b7de000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 comedi_buf_write_samples+0x371/0x5e0 drivers/comedi/comedi_buf.c:647
 das16m1_handler+0x212/0x4b0 drivers/comedi/drivers/das16m1.c:414
 das16m1_interrupt+0xa7/0x170 drivers/comedi/drivers/das16m1.c:471
 __handle_irq_event_percpu+0x299/0x9d0 kernel/irq/handle.c:156
 handle_irq_event_percpu kernel/irq/handle.c:196 [inline]
 handle_irq_event+0xa5/0x220 kernel/irq/handle.c:213
 handle_edge_irq+0x243/0xb20 kernel/irq/chip.c:819
 generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
 handle_irq arch/x86/kernel/irq.c:233 [inline]
 __common_interrupt+0xd7/0x1e0 arch/x86/kernel/irq.c:252
 common_interrupt+0xb0/0xd0 arch/x86/kernel/irq.c:242
 </IRQ>
 <TASK>
 asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:667
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 2f ca 8c f7 65 8b 05 d0 d7 3c 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc900032dfba0 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a06 RCX: 2708b44bb5e59700
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: 0000000000000001
RBP: ffffc900032dfc30 R08: ffffffff901d3117 R09: 1ffffffff203a622
R10: dffffc0000000000 R11: fffffbfff203a623 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffff966012c8 R15: 1ffff9200065bf74
 spin_unlock_irqrestore include/linux/spinlock.h:419 [inline]
 autoconfig drivers/tty/serial/8250/8250_port.c:1336 [inline]
 serial8250_config_port+0x1bbf/0x38d0 drivers/tty/serial/8250/8250_port.c:3195
 univ8250_config_port+0x3b1/0x960 drivers/tty/serial/8250/8250_core.c:446
 uart_do_autoconfig drivers/tty/serial/serial_core.c:1164 [inline]
 uart_ioctl+0x685/0x800 drivers/tty/serial/serial_core.c:1428
 tty_ioctl+0x84c/0xc20 drivers/tty/tty_io.c:2810
 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: 0033:0x7fd6ddb03799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd6dbd5d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd6ddd7cfa0 RCX: 00007fd6ddb03799
RDX: 0000000000000000 RSI: 0000000000005453 RDI: 0000000000000003
RBP: 00007fd6ddb99bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd6ddd7d038 R14: 00007fd6ddd7cfa0 R15: 00007ffef1f28268
 </TASK>
Modules linked in:
---[ end trace ad965918d4da6026 ]---
RIP: 0010:comedi_inc_scan_progress+0x19e/0x430 drivers/comedi/drivers.c:563
Code: b6 0c 19 84 c9 0f 85 b8 01 00 00 03 45 34 4c 8d a5 88 00 00 00 4c 89 e1 48 c1 e9 03 0f b6 0c 19 84 c9 0f 85 c7 01 00 00 31 d2 <41> f7 34 24 41 89 17 45 89 ec eb 0f e8 01 de f5 f9 48 bb 00 00 00
RSP: 0018:ffffc90000007c80 EFLAGS: 00010046
RAX: 0000000000000001 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8880782c4200 R08: ffff8880782c4200 R09: 1ffff9200095f200
R10: dffffc0000000000 R11: fffff5200095f201 R12: ffff8880782c4288
R13: 0000000000000002 R14: 0000000000000000 R15: ffff8880782c4234
FS:  00007fd6dbd5d6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c32cb3b CR3: 000000002b7de000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	b6 0c                	mov    $0xc,%dh
   2:	19 84 c9 0f 85 b8 01 	sbb    %eax,0x1b8850f(%rcx,%rcx,8)
   9:	00 00                	add    %al,(%rax)
   b:	03 45 34             	add    0x34(%rbp),%eax
   e:	4c 8d a5 88 00 00 00 	lea    0x88(%rbp),%r12
  15:	4c 89 e1             	mov    %r12,%rcx
  18:	48 c1 e9 03          	shr    $0x3,%rcx
  1c:	0f b6 0c 19          	movzbl (%rcx,%rbx,1),%ecx
  20:	84 c9                	test   %cl,%cl
  22:	0f 85 c7 01 00 00    	jne    0x1ef
  28:	31 d2                	xor    %edx,%edx
* 2a:	41 f7 34 24          	divl   (%r12) <-- trapping instruction
  2e:	41 89 17             	mov    %edx,(%r15)
  31:	45 89 ec             	mov    %r13d,%r12d
  34:	eb 0f                	jmp    0x45
  36:	e8 01 de f5 f9       	call   0xf9f5de3c
  3b:	48                   	rex.W
  3c:	bb                   	.byte 0xbb
  3d:	00 00                	add    %al,(%rax)

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/27 16:52 linux-5.15.y 3330a8d33e08 2cf092b8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan divide error in comedi_inc_scan_progress
* Struck through repros no longer work on HEAD.