[v5.15] divide error in flush_commit_list (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3dea0e7f549e Linux 5.15.186
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1789ebd4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=644ffcb58c0b09d3
dashboard link: https://syzkaller.appspot.com/bug?extid=0ff5ada928883b381abb
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3d73d6f07b0c/disk-3dea0e7f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4064de18c9e9/vmlinux-3dea0e7f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/069c7b1e74a9/bzImage-3dea0e7f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0ff5ad...@syzkaller.appspotmail.com

divide error: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 21 Comm: kworker/1:0 Not tainted 5.15.186-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: reiserfs/loop9 flush_async_commits
RIP: 0010:flush_commit_list+0xb5f/0x1d70 fs/reiserfs/journal.c:1049
Code: df 42 0f b6 0c 21 84 c9 0f 85 be 01 00 00 49 83 c5 17 4c 89 e9 48 c1 e9 03 42 0f b6 0c 21 84 c9 0f 85 d5 01 00 00 8b 0b 31 d2 <48> f7 f1 48 89 d3 49 83 c6 18 4c 89 f0 48 c1 e8 03 42 80 3c 20 00
RSP: 0018:ffffc90000db7aa0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888057ad5014 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff888057ad500f
RBP: ffffc90000db7c08 R08: dffffc0000000000 R09: fffff520009f9282
R10: fffff520009f9282 R11: 1ffff920009f9281 R12: dffffc0000000000
R13: ffff888057ad5017 R14: ffff888042464000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f835c8fd000 CR3: 00000000607ad000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
flush_async_commits+0xa0/0xc0 fs/reiserfs/journal.c:3552
process_one_work+0x863/0x1000 kernel/workqueue.c:2310
worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
Modules linked in:
---[ end trace 046556e6e538e683 ]---
RIP: 0010:flush_commit_list+0xb5f/0x1d70 fs/reiserfs/journal.c:1049
Code: df 42 0f b6 0c 21 84 c9 0f 85 be 01 00 00 49 83 c5 17 4c 89 e9 48 c1 e9 03 42 0f b6 0c 21 84 c9 0f 85 d5 01 00 00 8b 0b 31 d2 <48> f7 f1 48 89 d3 49 83 c6 18 4c 89 f0 48 c1 e8 03 42 80 3c 20 00
RSP: 0018:ffffc90000db7aa0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888057ad5014 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff888057ad500f
RBP: ffffc90000db7c08 R08: dffffc0000000000 R09: fffff520009f9282
R10: fffff520009f9282 R11: 1ffff920009f9281 R12: dffffc0000000000
R13: ffff888057ad5017 R14: ffff888042464000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1ae037f000 CR3: 0000000062c8f000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: df 42 0f filds 0xf(%rdx)
3: b6 0c mov $0xc,%dh
5: 21 84 c9 0f 85 be 01 and %eax,0x1be850f(%rcx,%rcx,8)
c: 00 00 add %al,(%rax)
e: 49 83 c5 17 add $0x17,%r13
12: 4c 89 e9 mov %r13,%rcx
15: 48 c1 e9 03 shr $0x3,%rcx
19: 42 0f b6 0c 21 movzbl (%rcx,%r12,1),%ecx
1e: 84 c9 test %cl,%cl
20: 0f 85 d5 01 00 00 jne 0x1fb
26: 8b 0b mov (%rbx),%ecx
28: 31 d2 xor %edx,%edx
* 2a: 48 f7 f1 div %rcx <-- trapping instruction
2d: 48 89 d3 mov %rdx,%rbx
30: 49 83 c6 18 add $0x18,%r14
34: 4c 89 f0 mov %r14,%rax
37: 48 c1 e8 03 shr $0x3,%rax
3b: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1)


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.