[syzbot] memory leak in nilfs_sysfs_create_device_group

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    a5088ee7251e Merge tag 'thermal-6.1-rc1' of git://git.kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=153f2492880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=21254cf9c7c084e0
dashboard link: https://syzkaller.appspot.com/bug?extid=2e2f697dbd0f429d5dae
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1556a368880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c2d2c6d22fae/disk-a5088ee7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3c66d2393267/vmlinux-a5088ee7.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/f2050cc3fa6c/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2e2f697dbd0f429d5dae@xxxxxxxxxxxxxxxxxxxxxxxxx

BUG: memory leak
unreferenced object 0xffff888119526520 (size 32):
  comm "syz-executor.4", pid 4168, jiffies 4294949450 (age 9.260s)
  hex dump (first 32 bytes):
    6c 6f 6f 70 34 00 00 00 00 00 00 00 00 00 00 00  loop4...........
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff814c5b86>] kstrdup+0x36/0x70 mm/util.c:61
    [<ffffffff814c5c13>] kstrdup_const+0x53/0x80 mm/util.c:84
    [<ffffffff823af0e2>] kvasprintf_const+0xc2/0x110 lib/kasprintf.c:48
    [<ffffffff824a442b>] kobject_set_name_vargs+0x3b/0xe0 lib/kobject.c:257
    [<ffffffff824a48ad>] kobject_add_varg lib/kobject.c:352 [inline]
    [<ffffffff824a48ad>] kobject_init_and_add+0x6d/0xc0 lib/kobject.c:441
    [<ffffffff81e217ba>] nilfs_sysfs_create_device_group+0x9a/0x3d0 fs/nilfs2/sysfs.c:991
    [<ffffffff81e0a03c>] init_nilfs+0x51c/0x680 fs/nilfs2/the_nilfs.c:637
    [<ffffffff81df608b>] nilfs_fill_super fs/nilfs2/super.c:1047 [inline]
    [<ffffffff81df608b>] nilfs_mount+0x51b/0x890 fs/nilfs2/super.c:1317
    [<ffffffff8164f4ab>] legacy_get_tree+0x2b/0x90 fs/fs_context.c:610
    [<ffffffff815e8c48>] vfs_get_tree+0x28/0x100 fs/super.c:1530
    [<ffffffff8162cbd7>] do_new_mount fs/namespace.c:3040 [inline]
    [<ffffffff8162cbd7>] path_mount+0xc37/0x10d0 fs/namespace.c:3370
    [<ffffffff8162d7be>] do_mount fs/namespace.c:3383 [inline]
    [<ffffffff8162d7be>] __do_sys_mount fs/namespace.c:3591 [inline]
    [<ffffffff8162d7be>] __se_sys_mount fs/namespace.c:3568 [inline]
    [<ffffffff8162d7be>] __x64_sys_mount+0x18e/0x1d0 fs/namespace.c:3568
    [<ffffffff845ebbf5>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
    [<ffffffff845ebbf5>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
    [<ffffffff84800087>] entry_SYSCALL_64_after_hwframe+0x63/0xcd



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