[syzbot] [nilfs?] UBSAN: array-index-out-of-bounds in nilfs_add_link

[syzbot <syzbot+2e22057de05b9f3b30d8@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    fe46a7dd189e Merge tag 'sound-6.9-rc1' of git://git.kernel..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1777792b180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4d90a36f0cab495a
dashboard link: https://syzkaller.appspot.com/bug?extid=2e22057de05b9f3b30d8
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1176600b180000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15141b43180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/72ab73815344/disk-fe46a7dd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2d6d6b0d7071/vmlinux-fe46a7dd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/48e275e5478b/bzImage-fe46a7dd.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/de3bc2f4acaf/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2e22057de05b9f3b30d8@syzkaller.appspotmail.com

------------[ cut here ]------------
UBSAN: array-index-out-of-bounds in fs/nilfs2/dir.c:257:18
index 15 is out of range for type 'unsigned char[15]'
CPU: 0 PID: 5057 Comm: syz-executor165 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 ubsan_epilogue lib/ubsan.c:217 [inline]
 __ubsan_handle_out_of_bounds+0x121/0x150 lib/ubsan.c:415
 nilfs_set_de_type fs/nilfs2/dir.c:257 [inline]
 nilfs_add_link+0xb39/0xb80 fs/nilfs2/dir.c:501
 nilfs_link+0x136/0x220 fs/nilfs2/namei.c:192
 vfs_link+0x4f5/0x690 fs/namei.c:4608
 do_linkat+0x356/0x760 fs/namei.c:4679
 __do_sys_linkat fs/namei.c:4707 [inline]
 __se_sys_linkat fs/namei.c:4704 [inline]
 __x64_sys_linkat+0xdd/0xf0 fs/namei.c:4704
 do_syscall_64+0xfb/0x240
 entry_SYSCALL_64_after_hwframe+0x6d/0x75
RIP: 0033:0x7f0624efc679
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 17 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff6dc40a98 EFLAGS: 00000246 ORIG_RAX: 0000000000000109
RAX: ffffffffffffffda RBX: 00007fff6dc40c68 RCX: 00007f0624efc679
RDX: 0000000000000004 RSI: 0000000020000180 RDI: 0000000000000004
RBP: 00007f0624f70610 R08: 0000000000000000 R09: 00007fff6dc40c68
R10: 0000000020000640 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fff6dc40c58 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
---[ end trace ]---


---
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 syzkaller@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 syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

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