[syzbot] [kernel?] divide error in comedi_inc_scan_progress

From: syzbot
Date: Tue Jul 08 2025 - 13:52:47 EST

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Hello,

syzbot found the following issue on:

HEAD commit: d7b8f8e20813 Linux 6.16-rc5
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1250d28c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f51185bd4f40ad44
dashboard link: https://syzkaller.appspot.com/bug?extid=af53dea94b16396bc646
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f933e0e4a6c5/disk-d7b8f8e2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a82be954c91b/vmlinux-d7b8f8e2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/66dbc3de1264/bzImage-d7b8f8e2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+af53dea94b16396bc646@xxxxxxxxxxxxxxxxxxxxxxxxx

Oops: divide error: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 9896 Comm: syz.3.1000 Not tainted 6.16.0-rc5-syzkaller #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:ffffc90000007da0 EFLAGS: 00010046
RAX: 0000000000000001 RBX: ffff88807af3e400 RCX: 1ffff1100f5e7c90
RDX: 0000000000000000 RSI: ffffffff88ee6f98 RDI: ffff88807af3e480
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000004
R13: 0000000000000000 R14: 0000000000000002 R15: 0000000010000000
FS: 00007f7abf9b16c0(0000) GS:ffff888124718000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000084030 CR3: 00000000317d4000 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+0xdf/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:csd_lock_wait kernel/smp.c:340 [inline]
RIP: 0010:smp_call_function_many_cond+0xd7b/0x1510 kernel/smp.c:885
Code: e8 6a 19 0c 00 45 85 ed 74 46 48 8b 14 24 49 89 d6 49 89 d5 49 c1 ee 03 41 83 e5 07 4d 01 e6 41 83 c5 03 e8 07 1e 0c 00 f3 90 <41> 0f b6 06 41 38 c5 7c 08 84 c0 0f 85 6f 05 00 00 8b 43 08 31 ff
RSP: 0018:ffffc9000214f2b8 EFLAGS: 00000246
RAX: 0000000000080000 RBX: ffff8880b853fe20 RCX: ffffc9000f741000
RDX: 0000000000080000 RSI: ffffffff81afc8a9 RDI: 0000000000000005
RBP: 0000000000000001 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: dffffc0000000000
R13: 0000000000000003 R14: ffffed10170a7fc5 R15: ffff8880b843b580
on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1052
__flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline]
flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
flush_tlb_mm_range+0x4a0/0x1790 arch/x86/mm/tlb.c:1451
flush_tlb_page arch/x86/include/asm/tlbflush.h:324 [inline]
ptep_clear_flush+0x136/0x180 mm/pgtable-generic.c:101
wp_page_copy mm/memory.c:3635 [inline]
do_wp_page+0x1683/0x4f20 mm/memory.c:4030
handle_pte_fault mm/memory.c:6085 [inline]
__handle_mm_fault+0x2223/0x5490 mm/memory.c:6212
handle_mm_fault+0x589/0xd10 mm/memory.c:6381
do_user_addr_fault+0x7a6/0x1370 arch/x86/mm/fault.c:1387
handle_page_fault arch/x86/mm/fault.c:1476 [inline]
exc_page_fault+0x5c/0xb0 arch/x86/mm/fault.c:1532
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
RIP: 0010:__put_user_nocheck_4+0x3/0x10 arch/x86/lib/putuser.S:104
Code: d9 0f 01 cb 89 01 31 c9 0f 01 ca c3 cc cc cc cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 01 cb <89> 01 31 c9 0f 01 ca e9 c1 5a 03 00 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000214f9f8 EFLAGS: 00050246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000200000084030
RDX: 0000000000080000 RSI: ffffffff89561a63 RDI: 0000000000000005
RBP: ffffc9000214fd98 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000001 R12: 0000000000000000
R13: 0000200000084000 R14: ffffc9000214fddc R15: 0000000000000002
____sys_recvmsg+0x2ee/0x6b0 net/socket.c:2799
___sys_recvmsg+0x114/0x1a0 net/socket.c:2828
do_recvmmsg+0x2fe/0x750 net/socket.c:2923
__sys_recvmmsg net/socket.c:2997 [inline]
__do_sys_recvmmsg net/socket.c:3020 [inline]
__se_sys_recvmmsg net/socket.c:3013 [inline]
__x64_sys_recvmmsg+0x22a/0x280 net/socket.c:3013
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: 0033:0x7f7abeb8e929
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:00007f7abf9b1038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f7abedb6160 RCX: 00007f7abeb8e929
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000008
RBP: 00007f7abec10b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f7abedb6160 R15: 00007fff425d3008
</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:ffffc90000007da0 EFLAGS: 00010046
RAX: 0000000000000001 RBX: ffff88807af3e400 RCX: 1ffff1100f5e7c90
RDX: 0000000000000000 RSI: ffffffff88ee6f98 RDI: ffff88807af3e480
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000004
R13: 0000000000000000 R14: 0000000000000002 R15: 0000000010000000
FS: 00007f7abf9b16c0(0000) GS:ffff888124718000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000084030 CR3: 00000000317d4000 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

---
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Next message: Frank Li: "Re: [PATCH] PCI: endpoint: pci-epf-vntb: fix MW2 configfs id"
Previous message: syzbot: "[syzbot] [mm?] stack segment fault in mtree_range_walk"
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