syzbot
divide error in comedi_inc_scan_progress (3)
Status:
upstream: reported on 2026/10/03 13:05
Reported-by: syzbot+d7d5d94b0246c6b53329@syzkaller.appspotmail.com
First crash: 13d, last: 13d
Sample crash report:
divide error: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 5640 Comm: syz.9.10484 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:comedi_inc_scan_progress+0x1a9/0x420 drivers/comedi/drivers.c:562
Code: 0c 29 84 c9 0f 85 ad 01 00 00 03 43 34 4c 8d a3 88 00 00 00 4c 89 e1 48 c1 e9 03 42 0f b6 0c 29 84 c9 0f 85 b3 01 00 00 31 d2 <41> f7 34 24 41 89 17 eb 05 e8 19 9f 6b f9 4c 8d 63 3c 4d 89 e7 49
RSP: 0018:ffffc90000007c90 EFLAGS: 00010046
RAX: 0000000000000001 RBX: ffff88802f26b600 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000002 R08: 00000000000000ff R09: 00000000000000ff
R10: dffffc0000000000 R11: fffff52001a38001 R12: ffff88802f26b688
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff88802f26b634
FS: 00007ff7f249c6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b34723ff8 CR3: 00000000697d2000 CR4: 00000000003506f0
Call Trace:
<IRQ>
comedi_buf_write_samples+0x375/0x5d0 drivers/comedi/comedi_buf.c:646
das16m1_handler+0x23a/0x4d0 drivers/comedi/drivers/das16m1.c:413
das16m1_interrupt+0xab/0x180 drivers/comedi/drivers/das16m1.c:470
__handle_irq_event_percpu+0x271/0x940 kernel/irq/handle.c:158
handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:210
handle_edge_irq+0x246/0xb20 kernel/irq/chip.c:831
generic_handle_irq_desc include/linux/irqdesc.h:161 [inline]
handle_irq arch/x86/kernel/irq.c:240 [inline]
__common_interrupt+0x13b/0x230 arch/x86/kernel/irq.c:259
common_interrupt+0xb4/0xd0 arch/x86/kernel/irq.c:249
</IRQ>
<TASK>
asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:678
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xc0/0x120 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> ab 96 c0 f6 65 8b 05 1c 54 67 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc90016387a40 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a06 RCX: 976060fcce3d2c00
RDX: dffffc0000000000 RSI: ffffffff8acacce0 RDI: 0000000000000001
RBP: ffffc90016387ad0 R08: ffffffff911f0557 R09: 1ffffffff223e0aa
R10: dffffc0000000000 R11: fffffbfff223e0ab R12: dffffc0000000000
R13: ffffffff9762aec0 R14: ffffffff9762aec0 R15: 1ffff92002c70f48
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
autoconfig drivers/tty/serial/8250/8250_port.c:1307 [inline]
serial8250_config_port+0x2402/0x36b0 drivers/tty/serial/8250/8250_port.c:3234
univ8250_config_port+0x397/0x940 drivers/tty/serial/8250/8250_core.c:445
uart_do_autoconfig drivers/tty/serial/serial_core.c:1204 [inline]
uart_ioctl+0xe53/0x1040 drivers/tty/serial/serial_core.c:1603
tty_ioctl+0x91e/0xdc0 drivers/tty/tty_io.c:2779
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:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff7f159e159
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:00007ff7f249c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ff7f1825fa0 RCX: 00007ff7f159e159
RDX: 0000000000000000 RSI: 0000000000005453 RDI: 0000000000000003
RBP: 00007ff7f163506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff7f1826038 R14: 00007ff7f1825fa0 R15: 00007ffe80fa58f8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:comedi_inc_scan_progress+0x1a9/0x420 drivers/comedi/drivers.c:562
Code: 0c 29 84 c9 0f 85 ad 01 00 00 03 43 34 4c 8d a3 88 00 00 00 4c 89 e1 48 c1 e9 03 42 0f b6 0c 29 84 c9 0f 85 b3 01 00 00 31 d2 <41> f7 34 24 41 89 17 eb 05 e8 19 9f 6b f9 4c 8d 63 3c 4d 89 e7 49
RSP: 0018:ffffc90000007c90 EFLAGS: 00010046
RAX: 0000000000000001 RBX: ffff88802f26b600 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000002 R08: 00000000000000ff R09: 00000000000000ff
R10: dffffc0000000000 R11: fffff52001a38001 R12: ffff88802f26b688
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff88802f26b634
FS: 00007ff7f249c6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b34723ff8 CR3: 00000000697d2000 CR4: 00000000003506f0
----------------
Code disassembly (best guess):
0: 0c 29 or $0x29,%al
2: 84 c9 test %cl,%cl
4: 0f 85 ad 01 00 00 jne 0x1b7
a: 03 43 34 add 0x34(%rbx),%eax
d: 4c 8d a3 88 00 00 00 lea 0x88(%rbx),%r12
14: 4c 89 e1 mov %r12,%rcx
17: 48 c1 e9 03 shr $0x3,%rcx
1b: 42 0f b6 0c 29 movzbl (%rcx,%r13,1),%ecx
20: 84 c9 test %cl,%cl
22: 0f 85 b3 01 00 00 jne 0x1db
28: 31 d2 xor %edx,%edx
* 2a: 41 f7 34 24 divl (%r12) <-- trapping instruction
2e: 41 89 17 mov %edx,(%r15)
31: eb 05 jmp 0x38
33: e8 19 9f 6b f9 call 0xf96b9f51
38: 4c 8d 63 3c lea 0x3c(%rbx),%r12
3c: 4d 89 e7 mov %r12,%r15
3f: 49 rex.WB
Struck through repros no longer work on HEAD.