syzbot


divide error in comedi_inc_scan_progress

Status: upstream: reported on 2025/12/10 08:43
Reported-by: syzbot+2bcaaae2c36c1b70a448@syzkaller.appspotmail.com
First crash: 136d, last: 21d
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 divide error in comedi_inc_scan_progress (2) 2 3 8d14h 56d 0/3 upstream: reported on 2026/02/27 16:53
linux-6.6 divide error in comedi_inc_scan_progress (2) 2 8 27d 171d 0/2 upstream: reported on 2025/11/05 08:13
linux-6.6 divide error in comedi_inc_scan_progress 2 2 274d 277d 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 139d 290d 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 157d 157d 0/3 auto-obsoleted due to no activity on 2026/02/27 00:49

Sample crash report:
divide error: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 20958 Comm: syz.6.4683 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:562
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 41 37 b4 f9 48 bb 00 00 00
RSP: 0018:ffffc90000007c80 EFLAGS: 00010046
RAX: 0000000000000001 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8880278e0600 R08: ffff8880278e0600 R09: 1ffff92001a9d600
R10: dffffc0000000000 R11: fffff52001a9d601 R12: ffff8880278e0688
R13: 0000000000000002 R14: 0000000000000000 R15: ffff8880278e0634
FS:  00007f4f005f66c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000019a63000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 comedi_buf_write_samples+0x36e/0x5d0 drivers/comedi/comedi_buf.c:646
 das16m1_handler+0x213/0x4b0 drivers/comedi/drivers/das16m1.c:413
 das16m1_interrupt+0xa7/0x170 drivers/comedi/drivers/das16m1.c:470
 __handle_irq_event_percpu+0x293/0xa50 kernel/irq/handle.c:158
 handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
 handle_irq_event+0x87/0x1e0 kernel/irq/handle.c:210
 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:682
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [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> df 0d 21 f7 65 8b 05 30 91 ca 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc9000e587c00 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: 493c6e5a1c588300
RDX: dffffc0000000000 RSI: ffffffff8a8c10a0 RDI: 0000000000000001
RBP: ffffc9000e587c90 R08: ffffffff90af72df R09: 1ffffffff215ee5b
R10: dffffc0000000000 R11: fffffbfff215ee5c R12: dffffc0000000000
R13: ffffffff96f85f70 R14: ffffffff96f85f70 R15: 1ffff92001cb0f80
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 uart_write+0x68a/0x910 drivers/tty/serial/serial_core.c:602
 tnc_init drivers/net/hamradio/6pack.c:496 [inline]
 sixpack_open+0x707/0x9a0 drivers/net/hamradio/6pack.c:591
 tty_ldisc_open+0x9d/0x100 drivers/tty/tty_ldisc.c:433
 tty_set_ldisc+0x370/0x550 drivers/tty/tty_ldisc.c:564
 tty_ioctl+0xa1e/0xba0 drivers/tty/tty_io.c:2712
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4f0239c819
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:00007f4f005f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f4f02615fa0 RCX: 00007f4f0239c819
RDX: 0000200000000100 RSI: 0000000000005423 RDI: 0000000000000003
RBP: 00007f4f02432c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4f02616038 R14: 00007f4f02615fa0 R15: 00007ffdbe167738
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:comedi_inc_scan_progress+0x19e/0x430 drivers/comedi/drivers.c:562
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 41 37 b4 f9 48 bb 00 00 00
RSP: 0018:ffffc90000007c80 EFLAGS: 00010046
RAX: 0000000000000001 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8880278e0600 R08: ffff8880278e0600 R09: 1ffff92001a9d600
R10: dffffc0000000000 R11: fffff52001a9d601 R12: ffff8880278e0688
R13: 0000000000000002 R14: 0000000000000000 R15: ffff8880278e0634
FS:  00007f4f005f66c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000019a63000 CR4: 00000000003526f0
----------------
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 41 37 b4 f9       	call   0xf9b4377c
  3b:	48                   	rex.W
  3c:	bb                   	.byte 0xbb
  3d:	00 00                	add    %al,(%rax)

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/03 23:00 linux-6.1.y 1989cd3d56e2 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan divide error in comedi_inc_scan_progress
2026/03/29 11:16 linux-6.1.y 1989cd3d56e2 b5ceaad2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan divide error in comedi_inc_scan_progress
2026/01/30 05:01 linux-6.1.y cd9b81672742 bfa73b7b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan divide error in comedi_inc_scan_progress
2025/12/10 08:42 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan divide error in comedi_inc_scan_progress
* Struck through repros no longer work on HEAD.