bisecting fixing commit since c076c79e03c6094e578df5d210fde808b3ad32e6
building syzkaller on 4ca1c0ea446d2c09b1fb49a85ae645e3754f1058
testing commit c076c79e03c6094e578df5d210fde808b3ad32e6 with gcc (GCC) 8.4.1 20210217
kernel signature: 635709f5c1e60317163e36e3a60eacbb6ab8543f6f8126c648d1474f9cb42514
all runs: crashed: BUG: corrupted list in l2cap_chan_put
testing current HEAD 3c8c23092588a23bf1856a64f58c37f477a413be
testing commit 3c8c23092588a23bf1856a64f58c37f477a413be with gcc (GCC) 8.4.1 20210217
kernel signature: 1ecdb28f7e55b7a4d5792c8d301b664622785d86924831ebef289beb5796fd7d
all runs: crashed: BUG: corrupted list in l2cap_chan_put
revisions tested: 2, total time: 37m11.026987541s (build: 22m47.975562441s, test: 13m50.998957435s)
the crash still happens on HEAD
commit msg: Linux 4.19.190
crash: BUG: corrupted list in l2cap_chan_put
Bluetooth: hci5: command 0x0409 tx timeout
Bluetooth: hci0: command 0x041b tx timeout
Bluetooth: hci1: command 0x041b tx timeout
list_del corruption, ffff8881e7e2a508->next is LIST_POISON1 (dead000000000100)
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:47!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 7233 Comm: kworker/u5:1 Not tainted 4.19.190-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci2 hci_rx_work
RIP: 0010:__list_del_entry_valid.cold.1+0x26/0x4a lib/list_debug.c:45
Code: f9 ff 0f 0b 4c 89 e2 48 89 de 48 c7 c7 80 a0 67 87 e8 e7 67 f9 ff 0f 0b 4c 89 ea 48 89 de 48 c7 c7 20 a0 67 87 e8 d3 67 f9 ff <0f> 0b 48 89 de 48 c7 c7 40 a1 67 87 e8 c2 67 f9 ff 0f 0b 48 89 de
RSP: 0018:ffff8881dc1776f8 EFLAGS: 00010282
RAX: 000000000000004e RBX: ffff8881e7e2a508 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff87679d80 RDI: ffffffff8a1a0aa0
RBP: ffff8881dc177710 R08: ffffed103ed25081 R09: ffffed103ed25080
R10: ffffed103ed25080 R11: ffff8881f6928407 R12: dead000000000200
R13: dead000000000100 R14: ffff8881e2f2fc00 R15: ffff8881e2f2fc80
FS:  0000000000000000(0000) GS:ffff8881f6900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004bb868 CR3: 000000000846d001 CR4: 00000000001606e0
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 include/linux/list.h:125 [inline]
 l2cap_chan_destroy net/bluetooth/l2cap_core.c:479 [inline]
 kref_put include/linux/kref.h:70 [inline]
 l2cap_chan_put+0x49/0x1a0 net/bluetooth/l2cap_core.c:496
 l2cap_conless_channel net/bluetooth/l2cap_core.c:6982 [inline]
 l2cap_recv_frame+0xf29/0xa430 net/bluetooth/l2cap_core.c:7029
 l2cap_recv_acldata+0x756/0x8a0 net/bluetooth/l2cap_core.c:7594
 hci_acldata_packet net/bluetooth/hci_core.c:4180 [inline]
 hci_rx_work+0x5d6/0x8f0 net/bluetooth/hci_core.c:4366
 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2152
 worker_thread+0x85/0xb60 kernel/workqueue.c:2295
 kthread+0x347/0x410 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Modules linked in:
---[ end trace b35a6dd44fb5c362 ]---
RIP: 0010:__list_del_entry_valid.cold.1+0x26/0x4a lib/list_debug.c:45
Code: f9 ff 0f 0b 4c 89 e2 48 89 de 48 c7 c7 80 a0 67 87 e8 e7 67 f9 ff 0f 0b 4c 89 ea 48 89 de 48 c7 c7 20 a0 67 87 e8 d3 67 f9 ff <0f> 0b 48 89 de 48 c7 c7 40 a1 67 87 e8 c2 67 f9 ff 0f 0b 48 89 de
RSP: 0018:ffff8881dc1776f8 EFLAGS: 00010282
RAX: 000000000000004e RBX: ffff8881e7e2a508 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff87679d80 RDI: ffffffff8a1a0aa0
RBP: ffff8881dc177710 R08: ffffed103ed25081 R09: ffffed103ed25080
R10: ffffed103ed25080 R11: ffff8881f6928407 R12: dead000000000200
R13: dead000000000100 R14: ffff8881e2f2fc00 R15: ffff8881e2f2fc80
FS:  0000000000000000(0000) GS:ffff8881f6900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004bb868 CR3: 000000000846d001 CR4: 00000000001606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400