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: 54d, last: 5d23h
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 8 25d 168d 0/2 upstream: reported on 2025/11/05 08:13
linux-6.6 divide error in comedi_inc_scan_progress 2 2 272d 274d 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 137d 288d 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 155d 155d 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 4 19d 133d 0/3 upstream: reported on 2025/12/10 08:43

Sample crash report:
divide error: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 4548 Comm: kworker/0:21 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: rcu_gp process_srcu
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 91 bc 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: ffff888022944400 R08: ffff888022944400 R09: 1ffff92000909200
R10: dffffc0000000000 R11: fffff52000909201 R12: ffff888022944488
R13: 0000000000000002 R14: 0000000000000000 R15: ffff888022944434
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005644c75c9000 CR3: 00000000769c9000 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:queue_delayed_work_on+0x1a7/0x1f0 kernel/workqueue.c:1720
Code: 4d 85 ed 75 16 e8 89 1f 2b 00 eb 15 e8 82 1f 2b 00 e8 3d 67 6e 08 4d 85 ed 74 ea e8 73 1f 2b 00 fb 48 c7 44 24 20 0e 36 e0 45 <48> b8 00 00 00 00 00 fc ff df 49 c7 04 06 00 00 00 00 41 c7 44 06
RSP: 0018:ffffc90003f7fb60 EFLAGS: 00000293
RAX: ffffffff814e019d RBX: 0000000000000000 RCX: ffff888020175940
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003f7fc30 R08: ffffffff901d40d7 R09: 1ffffffff203a81a
R10: dffffc0000000000 R11: fffffbfff203a81b R12: dffffc0000000001
R13: 0000000000000200 R14: 1ffff920007eff70 R15: 0000000000000000
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Modules linked in:
---[ end trace bda19c28e211046e ]---
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 91 bc 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: ffff888022944400 R08: ffff888022944400 R09: 1ffff92000909200
R10: dffffc0000000000 R11: fffff52000909201 R12: ffff888022944488
R13: 0000000000000002 R14: 0000000000000000 R15: ffff888022944434
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005644c75c9000 CR3: 00000000769c9000 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 91 bc f5 f9       	call   0xf9f5bccc
  3b:	48                   	rex.W
  3c:	bb                   	.byte 0xbb
  3d:	00 00                	add    %al,(%rax)

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/17 01:11 linux-5.15.y 91d48252ad4b de0a551d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan divide error in comedi_inc_scan_progress
2026/04/17 01:11 linux-5.15.y 91d48252ad4b de0a551d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan divide error in comedi_inc_scan_progress
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.