syzbot


divide error in comedi_inc_scan_progress

Status: upstream: reported on 2025/07/08 17:52
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+af53dea94b16396bc646@syzkaller.appspotmail.com
First crash: 6d08h, last: 5d04h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernel?] divide error in comedi_inc_scan_progress 0 (1) 2025/07/08 17:52

Sample crash report:
Oops: divide error: 0000 [#1] SMP KASAN NOPTI
CPU: 1 UID: 0 PID: 16685 Comm: syz.4.2887 Not tainted 6.16.0-rc5-syzkaller-00025-gd006330be3f7 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:comedi_inc_scan_progress+0x1cc/0x340 drivers/comedi/drivers.c:556
Code: 00 00 00 03 43 2c 48 ba 00 00 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 0f b6 14 11 84 d2 74 09 80 fa 03 0f 8e 53 01 00 00 31 d2 <f7> b3 80 00 00 00 89 53 2c e8 a6 76 cd f8 48 8d 7b 34 48 b8 00 00
RSP: 0018:ffffc90000a08da0 EFLAGS: 00010046
RAX: 0000000000000001 RBX: ffff88807a2ee200 RCX: 1ffff1100f45dc50
RDX: 0000000000000000 RSI: ffffffff88ee7f98 RDI: ffff88807a2ee280
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000004
R13: 0000000000000000 R14: 0000000000000002 R15: 0000000010000000
FS:  00007f78edbeb6c0(0000) GS:ffff888124816000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000556a8bf57000 CR3: 0000000030b9e000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 comedi_buf_write_samples+0x406/0x640 drivers/comedi/comedi_buf.c:603
 aio_iiro_16_cos+0x132/0x160 drivers/comedi/drivers/aio_iiro_16.c:69
 __handle_irq_event_percpu+0x22c/0x7d0 kernel/irq/handle.c:158
 handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
 handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210
 handle_edge_irq+0x28e/0xab0 kernel/irq/chip.c:797
 generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
 handle_irq arch/x86/kernel/irq.c:254 [inline]
 call_irq_handler arch/x86/kernel/irq.c:266 [inline]
 __common_interrupt+0xe2/0x250 arch/x86/kernel/irq.c:292
 common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:285
 </IRQ>
 <TASK>
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:194
Code: f5 53 48 8b 74 24 10 48 89 fb 48 83 c7 18 e8 86 c1 0d f6 48 89 df e8 6e 15 0e f6 f7 c5 00 02 00 00 75 23 9c 58 f6 c4 02 75 37 <bf> 01 00 00 00 e8 05 33 fe f5 65 8b 05 9e d9 45 08 85 c0 74 16 5b
RSP: 0018:ffffc9000c7ffbb0 EFLAGS: 00000246
RAX: 0000000000000002 RBX: ffffffff9b0c4da0 RCX: 0000000000000006
RDX: 0000000000000000 RSI: ffffffff8de3251e RDI: ffffffff8c158f60
RBP: 0000000000000283 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff90a97f57 R11: 0000000000000001 R12: 0000000000000001
R13: ffffffff9b0c4ea8 R14: 0000000000000000 R15: 0000000000000003
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 uart_port_unlock_irqrestore include/linux/serial_core.h:788 [inline]
 uart_port_unlock_deref drivers/tty/serial/serial_core.c:91 [inline]
 uart_port_unlock_deref drivers/tty/serial/serial_core.c:88 [inline]
 uart_write+0x2a4/0xb30 drivers/tty/serial/serial_core.c:637
 tnc_init drivers/net/hamradio/6pack.c:525 [inline]
 sixpack_open+0x860/0xa40 drivers/net/hamradio/6pack.c:617
 tty_ldisc_open+0x9c/0x120 drivers/tty/tty_ldisc.c:432
 tty_set_ldisc+0x32b/0x780 drivers/tty/tty_ldisc.c:563
 tiocsetd drivers/tty/tty_io.c:2429 [inline]
 tty_ioctl+0xc2e/0x1640 drivers/tty/tty_io.c:2728
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl fs/ioctl.c:893 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f78ecd8e929
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:00007f78edbeb038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f78ecfb5fa0 RCX: 00007f78ecd8e929
RDX: 00002000000000c0 RSI: 0000000000005423 RDI: 0000000000000008
RBP: 00007f78ece10b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f78ecfb5fa0 R15: 00007ffe627ad408
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:comedi_inc_scan_progress+0x1cc/0x340 drivers/comedi/drivers.c:556
Code: 00 00 00 03 43 2c 48 ba 00 00 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 0f b6 14 11 84 d2 74 09 80 fa 03 0f 8e 53 01 00 00 31 d2 <f7> b3 80 00 00 00 89 53 2c e8 a6 76 cd f8 48 8d 7b 34 48 b8 00 00
RSP: 0018:ffffc90000a08da0 EFLAGS: 00010046
RAX: 0000000000000001 RBX: ffff88807a2ee200 RCX: 1ffff1100f45dc50
RDX: 0000000000000000 RSI: ffffffff88ee7f98 RDI: ffff88807a2ee280
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000004
R13: 0000000000000000 R14: 0000000000000002 R15: 0000000010000000
FS:  00007f78edbeb6c0(0000) GS:ffff888124816000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000556a8bf57000 CR3: 0000000030b9e000 CR4: 00000000003526f0
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	00 00                	add    %al,(%rax)
   2:	03 43 2c             	add    0x2c(%rbx),%eax
   5:	48 ba 00 00 00 00 00 	movabs $0xdffffc0000000000,%rdx
   c:	fc ff df
   f:	48 89 f9             	mov    %rdi,%rcx
  12:	48 c1 e9 03          	shr    $0x3,%rcx
  16:	0f b6 14 11          	movzbl (%rcx,%rdx,1),%edx
  1a:	84 d2                	test   %dl,%dl
  1c:	74 09                	je     0x27
  1e:	80 fa 03             	cmp    $0x3,%dl
  21:	0f 8e 53 01 00 00    	jle    0x17a
  27:	31 d2                	xor    %edx,%edx
* 29:	f7 b3 80 00 00 00    	divl   0x80(%rbx) <-- trapping instruction
  2f:	89 53 2c             	mov    %edx,0x2c(%rbx)
  32:	e8 a6 76 cd f8       	call   0xf8cd76dd
  37:	48 8d 7b 34          	lea    0x34(%rbx),%rdi
  3b:	48                   	rex.W
  3c:	b8                   	.byte 0xb8

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/09 03:38 upstream d006330be3f7 abade794 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root divide error in comedi_inc_scan_progress
2025/07/08 03:22 upstream d7b8f8e20813 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root divide error in comedi_inc_scan_progress
2025/07/08 00:11 upstream d7b8f8e20813 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root divide error in comedi_inc_scan_progress
* Struck through repros no longer work on HEAD.