------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 9784 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
Modules linked in:
CPU: 1 PID: 9784 Comm: syz-executor.5 Not tainted 5.14.0-next-20210907-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
Code: 09 31 ff 89 de e8 27 71 9e fd 84 db 0f 85 36 ff ff ff e8 da 6a 9e fd 48 c7 c7 00 06 e4 89 c6 05 36 54 82 09 01 e8 07 6e 18 05 <0f> 0b e9 17 ff ff ff e8 bb 6a 9e fd 0f b6 1d 1b 54 82 09 31 ff 89
RSP: 0018:ffffc900054d7920 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff8880848fd580 RSI: ffffffff815dbdb8 RDI: fffff52000a9af16
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815d5b9e R11: 0000000000000000 R12: ffff88801a9f3000
R13: 0000000000000000 R14: ffff8881473aa968 R15: ffff88801a9f3008
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000545f98 CR3: 00000000364d0000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __refcount_add include/linux/refcount.h:199 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 sock_hold include/net/sock.h:702 [inline]
 sco_conn_del+0x28a/0x2c0 net/bluetooth/sco.c:192
 sco_disconn_cfm+0x71/0xb0 net/bluetooth/sco.c:1213
 hci_disconn_cfm include/net/bluetooth/hci_core.h:1521 [inline]
 hci_conn_hash_flush+0x127/0x260 net/bluetooth/hci_conn.c:1613
 hci_dev_do_close+0x57d/0x1140 net/bluetooth/hci_core.c:1793
 hci_unregister_dev+0x1c0/0x5a0 net/bluetooth/hci_core.c:4020
 vhci_release+0x70/0xe0 drivers/bluetooth/hci_vhci.c:340
 __fput+0x288/0x9f0 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:32 [inline]
 do_exit+0xbae/0x2a30 kernel/exit.c:825
 do_group_exit+0x125/0x310 kernel/exit.c:922
 get_signal+0x47f/0x2160 kernel/signal.c:2868
 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665f9
Code: Unable to access opcode bytes at RIP 0x4665cf.
RSP: 002b:00007fdf53945218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000056c040 RCX: 00000000004665f9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000056c040
RBP: 000000000056c038 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c044
R13: 00007fffd9f46f5f R14: 00007fdf53945300 R15: 0000000000022000