------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 8334 at lib/refcount.c:25 refcount_warn_saturate+0x80/0xe0 lib/refcount.c:25
Modules linked in:
CPU: 1 PID: 8334 Comm: kworker/u5:5 Not tainted 5.10.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci4 hci_rx_work
RIP: 0010:refcount_warn_saturate+0x80/0xe0 lib/refcount.c:25
Code: 05 14 fe a0 02 01 e8 a3 9b 30 01 0f 0b c3 80 3d 04 fe a0 02 00 75 b8 48 c7 c7 60 ca f6 83 c6 05 f4 fd a0 02 01 e8 84 9b 30 01 <0f> 0b c3 80 3d e7 fd a0 02 00 75 99 48 c7 c7 38 ca f6 83 c6 05 d7
RSP: 0018:ffffc90000ea3cd0 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000002
RDX: 0000000000000002 RSI: ffffffff84074081 RDI: 00000000ffffffff
RBP: ffff88811ecd0800 R08: 0000000000000001 R09: 0000000000000001
R10: ffffc90000ea3b00 R11: ffffc90000ea3af8 R12: 0000000000000000
R13: 0000000000000001 R14: ffffffff8464dcc8 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000180 CR3: 000000011f17f000 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]
 kref_get include/linux/kref.h:45 [inline]
 l2cap_chan_hold net/bluetooth/l2cap_core.c:495 [inline]
 l2cap_global_chan_by_psm+0x1f8/0x220 net/bluetooth/l2cap_core.c:1978
 l2cap_conless_channel net/bluetooth/l2cap_core.c:7596 [inline]
 l2cap_recv_frame+0x554/0x2e40 net/bluetooth/l2cap_core.c:7666
 hci_acldata_packet net/bluetooth/hci_core.c:4740 [inline]
 hci_rx_work+0x1d3/0x500 net/bluetooth/hci_core.c:4931
 process_one_work+0x273/0x600 kernel/workqueue.c:2272
 worker_thread+0x38/0x380 kernel/workqueue.c:2418
 kthread+0x145/0x170 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296