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: 51d, last: 7h59m
Similar bugs (4)
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 4 10d 86d 0/2 upstream: reported on 2025/11/05 08:13
linux-6.6 divide error in comedi_inc_scan_progress 2 2 189d 192d 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 54d 205d 0/29 upstream: reported on 2025/07/08 17:52
linux-5.15 divide error in comedi_inc_scan_progress 2 2 72d 72d 0/3 upstream: reported on 2025/11/19 00:37

Sample crash report:
divide error: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 12442 Comm: dhcpcd-run-hook Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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 81 e5 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: ffff88807c507c00 R08: ffff88807c507c00 R09: 1ffff9200185a200
R10: dffffc0000000000 R11: fffff5200185a201 R12: ffff88807c507c88
R13: 0000000000000002 R14: 0000000000000000 R15: ffff88807c507c34
FS:  00007f1e2fdedc80(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055b6198eee38 CR3: 000000004e2e0000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
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:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x4/0x60 kernel/kcov.c:215
Code: 00 00 00 00 00 90 53 48 89 fb e8 17 00 00 00 48 8b 3d f0 52 9d 0c 48 89 de 5b e9 67 21 50 00 00 00 cc cc 00 00 cc 48 8b 04 24 <65> 48 8b 0d c4 fc 7f 7e 65 8b 15 c5 fc 7f 7e 81 e2 00 01 ff 00 74
RSP: 0018:ffffc9000d66f798 EFLAGS: 00000206
RAX: ffffffff8a1d55f6 RBX: 0000000000000005 RCX: 0000000000000000
RDX: ffff88802dba8000 RSI: 0000000000000064 RDI: 0000000000000000
RBP: 0000000000000012 R08: ffff88802dba8000 R09: 0000000000000012
R10: 0000000000000012 R11: 0000000000000000 R12: ffff88804da48800
R13: 0000000000000064 R14: 000000000000000d R15: fffffffffffffffe
 string_nocheck lib/vsprintf.c:646 [inline]
 string+0x206/0x2b0 lib/vsprintf.c:725
 vsnprintf+0x10da/0x1c20 lib/vsprintf.c:2805
 tomoyo_supervisor+0x15c/0x11a0 security/tomoyo/common.c:2060
 tomoyo_audit_path_log security/tomoyo/file.c:168 [inline]
 tomoyo_path_permission+0x25a/0x380 security/tomoyo/file.c:587
 tomoyo_path_perm+0x46a/0x610 security/tomoyo/file.c:838
 security_inode_getattr+0xcf/0x120 security/security.c:1361
 vfs_getattr+0x26/0x3a0 fs/stat.c:158
 vfs_fstat fs/stat.c:183 [inline]
 __do_sys_newfstat fs/stat.c:447 [inline]
 __se_sys_newfstat fs/stat.c:444 [inline]
 __x64_sys_newfstat+0x13d/0x220 fs/stat.c:444
 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: 0033:0x7f1e2ffa7ad7
Code: 73 01 c3 48 8b 0d 21 f3 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 05 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 f1 f2 0d 00 f7 d8 64 89 02 b8
RSP: 002b:00007fffd2616948 EFLAGS: 00000206 ORIG_RAX: 0000000000000005
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f1e2ffa7ad7
RDX: 0000000000090800 RSI: 00007fffd2616950 RDI: 0000000000000003
RBP: 00007fffd2616950 R08: 00007f1e30087ac0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 00007fffd2616b48
R13: 000055b6198eae69 R14: 0000000000000001 R15: 000055b6198ede29
 </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 81 e5 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: ffff88807c507c00 R08: ffff88807c507c00 R09: 1ffff9200185a200
R10: dffffc0000000000 R11: fffff5200185a201 R12: ffff88807c507c88
R13: 0000000000000002 R14: 0000000000000000 R15: ffff88807c507c34
FS:  00007f1e2fdedc80(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055b6198eee38 CR3: 000000004e2e0000 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 81 e5 b4 f9       	call   0xf9b4e5bc
  3b:	48                   	rex.W
  3c:	bb                   	.byte 0xbb
  3d:	00 00                	add    %al,(%rax)

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.