syzbot


divide error in ocfs2_block_group_fill

Status: upstream: reported on 2025/02/15 09:37
Subsystems: ocfs2
[Documentation on labels]
Reported-by: syzbot+e41e83af7a07a4df8051@syzkaller.appspotmail.com
First crash: 9d19h, last: 9d19h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ocfs2?] divide error in ocfs2_block_group_fill 0 (1) 2025/02/15 09:37

Sample crash report:
loop0: detected capacity change from 0 to 32768
=======================================================
WARNING: The mand mount option has been deprecated and
         and is ignored by this kernel. Remove the mand
         option from the mount to silence this warning.
=======================================================
JBD2: Ignoring recovery information on journal
ocfs2: Mounting device (7,0) on (node local, slot 0) with ordered data mode.
Oops: divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5324 Comm: syz.0.0 Not tainted 6.14.0-rc2-syzkaller-00034-gfebbc555cf0f #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:ocfs2_bg_discontig_add_extent fs/ocfs2/suballoc.c:335 [inline]
RIP: 0010:ocfs2_block_group_fill+0x5fa/0xbe0 fs/ocfs2/suballoc.c:386
Code: 00 4f 8d b4 35 50 01 00 00 45 0f b7 20 48 83 c6 02 49 89 f7 49 c1 ef 03 41 0f b6 04 3f 84 c0 0f 85 6e 04 00 00 44 89 e0 31 d2 <66> f7 36 0f b7 d8 4c 89 f0 48 c1 e8 03 0f b6 04 38 84 c0 0f 85 8e
RSP: 0018:ffffc9000d24ec20 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8880551e0158 RCX: 0000000000100000
RDX: 0000000000000000 RSI: ffff88804052a2c2 RDI: dffffc0000000000
RBP: ffffc9000d24ed28 R08: ffff8880551e000a R09: 1ffff1100aa3c001
R10: ffff8880551e0000 R11: ffffed100aa3c040 R12: 0000000000000000
R13: ffff8880551e0000 R14: ffff8880551e0150 R15: 1ffff110080a5458
FS:  00007f2117db36c0(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f210bdff000 CR3: 00000000402e4000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ocfs2_block_group_alloc_discontig fs/ocfs2/suballoc.c:634 [inline]
 ocfs2_block_group_alloc fs/ocfs2/suballoc.c:702 [inline]
 ocfs2_reserve_suballoc_bits+0x2358/0x4e70 fs/ocfs2/suballoc.c:832
 ocfs2_reserve_new_metadata_blocks+0x41c/0x9c0 fs/ocfs2/suballoc.c:982
 ocfs2_init_xattr_set_ctxt+0x3a6/0x8e0 fs/ocfs2/xattr.c:3277
 ocfs2_xattr_set+0xf4e/0x1930 fs/ocfs2/xattr.c:3634
 __vfs_setxattr+0x468/0x4a0 fs/xattr.c:200
 __vfs_setxattr_noperm+0x12e/0x660 fs/xattr.c:234
 vfs_setxattr+0x221/0x430 fs/xattr.c:321
 do_setxattr fs/xattr.c:636 [inline]
 filename_setxattr+0x2af/0x430 fs/xattr.c:665
 path_setxattrat+0x440/0x510 fs/xattr.c:713
 __do_sys_setxattr fs/xattr.c:747 [inline]
 __se_sys_setxattr fs/xattr.c:743 [inline]
 __x64_sys_setxattr+0xbc/0xe0 fs/xattr.c:743
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2116f8cde9
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:00007f2117db3038 EFLAGS: 00000246 ORIG_RAX: 00000000000000bc
RAX: ffffffffffffffda RBX: 00007f21171a5fa0 RCX: 00007f2116f8cde9
RDX: 0000000000000000 RSI: 00004000000003c0 RDI: 0000400000000180
RBP: 00007f211700e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f21171a5fa0 R15: 00007ffd982bc2e8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ocfs2_bg_discontig_add_extent fs/ocfs2/suballoc.c:335 [inline]
RIP: 0010:ocfs2_block_group_fill+0x5fa/0xbe0 fs/ocfs2/suballoc.c:386
Code: 00 4f 8d b4 35 50 01 00 00 45 0f b7 20 48 83 c6 02 49 89 f7 49 c1 ef 03 41 0f b6 04 3f 84 c0 0f 85 6e 04 00 00 44 89 e0 31 d2 <66> f7 36 0f b7 d8 4c 89 f0 48 c1 e8 03 0f b6 04 38 84 c0 0f 85 8e
RSP: 0018:ffffc9000d24ec20 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8880551e0158 RCX: 0000000000100000
RDX: 0000000000000000 RSI: ffff88804052a2c2 RDI: dffffc0000000000
RBP: ffffc9000d24ed28 R08: ffff8880551e000a R09: 1ffff1100aa3c001
R10: ffff8880551e0000 R11: ffffed100aa3c040 R12: 0000000000000000
R13: ffff8880551e0000 R14: ffff8880551e0150 R15: 1ffff110080a5458
FS:  00007f2117db36c0(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f210bc7c000 CR3: 00000000402e4000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	00 4f 8d             	add    %cl,-0x73(%rdi)
   3:	b4 35                	mov    $0x35,%ah
   5:	50                   	push   %rax
   6:	01 00                	add    %eax,(%rax)
   8:	00 45 0f             	add    %al,0xf(%rbp)
   b:	b7 20                	mov    $0x20,%bh
   d:	48 83 c6 02          	add    $0x2,%rsi
  11:	49 89 f7             	mov    %rsi,%r15
  14:	49 c1 ef 03          	shr    $0x3,%r15
  18:	41 0f b6 04 3f       	movzbl (%r15,%rdi,1),%eax
  1d:	84 c0                	test   %al,%al
  1f:	0f 85 6e 04 00 00    	jne    0x493
  25:	44 89 e0             	mov    %r12d,%eax
  28:	31 d2                	xor    %edx,%edx
* 2a:	66 f7 36             	divw   (%rsi) <-- trapping instruction
  2d:	0f b7 d8             	movzwl %ax,%ebx
  30:	4c 89 f0             	mov    %r14,%rax
  33:	48 c1 e8 03          	shr    $0x3,%rax
  37:	0f b6 04 38          	movzbl (%rax,%rdi,1),%eax
  3b:	84 c0                	test   %al,%al
  3d:	0f                   	.byte 0xf
  3e:	85                   	.byte 0x85
  3f:	8e                   	.byte 0x8e

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/11 09:26 upstream febbc555cf0f 43f51a00 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root divide error in ocfs2_block_group_fill
* Struck through repros no longer work on HEAD.