BUG: corrupted list in bt_accept_unlink

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 14b58326 Linux 4.14.193
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15de062c900000
kernel config: https://syzkaller.appspot.com/x/.config?x=68ef0287ccbc3b42
dashboard link: https://syzkaller.appspot.com/bug?extid=0bf38178a7de30898372
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1388be02900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0bf381...@syzkaller.appspotmail.com

Bluetooth: Wrong link type (-22)
Bluetooth: Wrong link type (-22)
list_del corruption. next->prev should be ffff888099f25610, but was ffff88808d591190
Bluetooth: Wrong link type (-22)
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:54!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 7779 Comm: kworker/u5:3 Not tainted 4.14.193-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci1 hci_rx_work
task: ffff8880a4992400 task.stack: ffff88808a058000
RIP: 0010:__list_del_entry_valid.cold+0x48/0x55 lib/list_debug.c:54
RSP: 0018:ffff88808a05f938 EFLAGS: 00010286
RAX: 0000000000000054 RBX: ffff888099f25610 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff86ac0dc0 RDI: ffffed101140bf1d
RBP: ffff888099f25610 R08: 0000000000000054 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88809ae3f110
R13: ffff88809ae3f110 R14: ffff88809ac2e2c0 R15: ffff8880a79b8b70
FS: 0000000000000000(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000051b800 CR3: 000000009c681000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__list_del_entry include/linux/list.h:117 [inline]
list_del_init include/linux/list.h:159 [inline]
bt_accept_unlink+0x26/0x200 net/bluetooth/af_bluetooth.c:187
l2cap_sock_teardown_cb+0x16b/0x400 net/bluetooth/l2cap_sock.c:1353
l2cap_chan_del+0xa0/0x800 net/bluetooth/l2cap_core.c:596
l2cap_disconnect_req net/bluetooth/l2cap_core.c:4349 [inline]
l2cap_bredr_sig_cmd net/bluetooth/l2cap_core.c:5427 [inline]
l2cap_sig_channel net/bluetooth/l2cap_core.c:5793 [inline]
l2cap_recv_frame+0x23b5/0x95c0 net/bluetooth/l2cap_core.c:7017
l2cap_recv_acldata+0x7a6/0x8b0 net/bluetooth/l2cap_core.c:7588
hci_acldata_packet net/bluetooth/hci_core.c:4066 [inline]
hci_rx_work+0x3d1/0x970 net/bluetooth/hci_core.c:4249
process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: 86 e8 83 ae 44 fe 0f 0b 4c 89 e2 48 89 ee 48 c7 c7 00 5e e4 86 e8 6f ae 44 fe 0f 0b 48 89 ee 48 c7 c7 c0 5e e4 86 e8 5e ae 44 fe <0f> 0b 90 90 90 90 90 90 90 90 90 90 90 83 3d f9 64 62 07 04 7f
RIP: __list_del_entry_valid.cold+0x48/0x55 lib/list_debug.c:54 RSP: ffff88808a05f938
---[ end trace 6e3c8c638c331e8e ]---


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