syzbot


divide error in flush_commit_list (3)

Status: upstream: reported on 2025/07/09 14:34
Reported-by: syzbot+0ff5ada928883b381abb@syzkaller.appspotmail.com
First crash: 8d02h, last: 8d02h
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 divide error in flush_commit_list (2) 2 5 276d 448d 0/3 auto-obsoleted due to no activity on 2025/01/22 10:35
upstream divide error in flush_commit_list reiserfs 2 24 567d 942d 0/29 auto-obsoleted due to no activity on 2024/04/06 13:39
linux-4.19 divide error in flush_commit_list 2 1 879d 879d 0/1 upstream: reported on 2023/02/18 21:03
linux-5.15 divide error in flush_commit_list 2 1 806d 806d 0/3 auto-obsoleted due to no activity on 2023/08/23 09:10

Sample crash report:
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)

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/09 14:33 linux-5.15.y 3dea0e7f549e f4e5e155 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan divide error in flush_commit_list
* Struck through repros no longer work on HEAD.