[v6.1] WARNING: refcount bug in device_move

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8e60a714ba3b Linux 6.1.132
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13c17404580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ebc45e145d6155ea
dashboard link: https://syzkaller.appspot.com/bug?extid=3877eed14c5d8cbde268
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c8b8da8486ff/disk-8e60a714.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ad79748d8748/vmlinux-8e60a714.xz
kernel image: https://storage.googleapis.com/syzbot-assets/28699fcb5d47/bzImage-8e60a714.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3877ee...@syzkaller.appspotmail.com

------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 8147 at lib/refcount.c:28 refcount_warn_saturate+0x14e/0x1a0 lib/refcount.c:28
Modules linked in:
CPU: 0 PID: 8147 Comm: syz-executor Not tainted 6.1.132-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:refcount_warn_saturate+0x14e/0x1a0 lib/refcount.c:28
Code: 0a 01 48 c7 c7 00 2f 5f 8b e8 8e d3 0e fd 0f 0b eb 8d e8 f5 bd 46 fd c6 05 41 71 48 0a 01 48 c7 c7 60 2f 5f 8b e8 72 d3 0e fd <0f> 0b e9 6e ff ff ff e8 d6 bd 46 fd c6 05 23 71 48 0a 01 48 c7 c7
RSP: 0018:ffffc9000587f818 EFLAGS: 00010246
RAX: 12ae59855a689500 RBX: 0000000000000003 RCX: ffff88801b6c8000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: ffffffff8152c26e R09: ffffed10171c4f1c
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff888056c44060
R13: ffff88805557d000 R14: ffffffff8552a740 R15: ffff888056c44078
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055555a162588 CR3: 0000000029c8a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__refcount_sub_and_test include/linux/refcount.h:283 [inline]
__refcount_dec_and_test include/linux/refcount.h:315 [inline]
refcount_dec_and_test include/linux/refcount.h:333 [inline]
kref_put include/linux/kref.h:64 [inline]
klist_dec_and_del+0x3e5/0x3f0 lib/klist.c:206
klist_put lib/klist.c:217 [inline]
klist_del lib/klist.c:230 [inline]
klist_remove+0x254/0x460 lib/klist.c:249
device_move+0x1b0/0x700 drivers/base/core.c:4633
hci_conn_del_sysfs+0xa8/0x150 net/bluetooth/hci_sysfs.c:73
hci_conn_cleanup+0x5a0/0x740 net/bluetooth/hci_conn.c:172
hci_conn_del+0x417/0x6c0 net/bluetooth/hci_conn.c:1151
hci_conn_hash_flush+0x205/0x2a0 net/bluetooth/hci_conn.c:2510
hci_dev_close_sync+0x9a9/0xfc0 net/bluetooth/hci_sync.c:5178
hci_dev_do_close net/bluetooth/hci_core.c:510 [inline]
hci_unregister_dev+0x207/0x500 net/bluetooth/hci_core.c:2707
vhci_release+0x7f/0xd0 drivers/bluetooth/hci_vhci.c:573
__fput+0x3f6/0x8d0 fs/file_table.c:320
task_work_run+0x246/0x300 kernel/task_work.c:203
exit_task_work include/linux/task_work.h:39 [inline]
do_exit+0xa6e/0x26a0 kernel/exit.c:871
do_group_exit+0x202/0x2b0 kernel/exit.c:1021
__do_sys_exit_group kernel/exit.c:1032 [inline]
__se_sys_exit_group kernel/exit.c:1030 [inline]
__x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1030
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f3e8078d169
Code: Unable to access opcode bytes at 0x7f3e8078d13f.
RSP: 002b:00007ffdf81fb5a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f3e8080e0b1 RCX: 00007f3e8078d169
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000002 R08: 00007ffdf81f9347 R09: 00007ffdf81fc860
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdf81fc860
R13: 00007f3e8080e08c R14: 00000000000c36a8 R15: 00007ffdf81fd930
</TASK>


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[syzbot]

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