bisecting fixing commit since c076c79e03c6094e578df5d210fde808b3ad32e6
building syzkaller on 4ca1c0ea446d2c09b1fb49a85ae645e3754f1058
testing commit c076c79e03c6094e578df5d210fde808b3ad32e6 with gcc (GCC) 8.4.1 20210217
kernel signature: 42dd857fcc13584de26774d541a843a594846a94cb22ac8aa0ea57faf5e0b50e
all runs: crashed: BUG: corrupted list in l2cap_chan_put
testing current HEAD eb575cd5d7f60241d016fdd13a9e86d962093c9b
testing commit eb575cd5d7f60241d016fdd13a9e86d962093c9b with gcc (GCC) 8.4.1 20210217
kernel signature: 76be1ef113b222b5d0d0e664f0c86a8d976821bc3b81b7268e9f66f2b94b93b1
all runs: crashed: BUG: corrupted list in l2cap_chan_put
revisions tested: 2, total time: 35m55.801064821s (build: 20m42.550551268s, test: 14m42.28804199s)
the crash still happens on HEAD
commit msg: Linux 4.19.195
crash: BUG: corrupted list in l2cap_chan_put
Bluetooth: hci5: command 0x0419 tx timeout
Bluetooth: hci4: command 0x0419 tx timeout
Bluetooth: hci3: command 0x0419 tx timeout
list_del corruption, ffff8881ed6c1708->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: 9294 Comm: kworker/u5:4 Not tainted 4.19.195-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci0 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 00 a4 67 87 e8 82 67 f9 ff 0f 0b 4c 89 ea 48 89 de 48 c7 c7 a0 a3 67 87 e8 6e 67 f9 ff <0f> 0b 48 89 de 48 c7 c7 c0 a4 67 87 e8 5d 67 f9 ff 0f 0b 48 89 de
RSP: 0018:ffff8881d0c876f8 EFLAGS: 00010282
RAX: 000000000000004e RBX: ffff8881ed6c1708 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8767a100 RDI: ffffffff8a19eaa0
RBP: ffff8881d0c87710 R08: ffffed103ed25081 R09: ffffed103ed25080
R10: ffffed103ed25080 R11: ffff8881f6928407 R12: dead000000000200
R13: dead000000000100 R14: ffff8881e58f6a40 R15: ffff8881e58f6ac0
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:481 [inline]
 kref_put include/linux/kref.h:70 [inline]
 l2cap_chan_put+0x49/0x1a0 net/bluetooth/l2cap_core.c:498
 l2cap_conless_channel net/bluetooth/l2cap_core.c:6986 [inline]
 l2cap_recv_frame+0xf29/0xa430 net/bluetooth/l2cap_core.c:7033
 l2cap_recv_acldata+0x756/0x8a0 net/bluetooth/l2cap_core.c:7598
 hci_acldata_packet net/bluetooth/hci_core.c:4185 [inline]
 hci_rx_work+0x5d6/0x8f0 net/bluetooth/hci_core.c:4371
 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2153
 worker_thread+0x85/0xb60 kernel/workqueue.c:2296
 kthread+0x347/0x410 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Modules linked in:
---[ end trace 31f5ebf07ec83e74 ]---
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 00 a4 67 87 e8 82 67 f9 ff 0f 0b 4c 89 ea 48 89 de 48 c7 c7 a0 a3 67 87 e8 6e 67 f9 ff <0f> 0b 48 89 de 48 c7 c7 c0 a4 67 87 e8 5d 67 f9 ff 0f 0b 48 89 de
RSP: 0018:ffff8881d0c876f8 EFLAGS: 00010282
RAX: 000000000000004e RBX: ffff8881ed6c1708 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8767a100 RDI: ffffffff8a19eaa0
RBP: ffff8881d0c87710 R08: ffffed103ed25081 R09: ffffed103ed25080
R10: ffffed103ed25080 R11: ffff8881f6928407 R12: dead000000000200
R13: dead000000000100 R14: ffff8881e58f6a40 R15: ffff8881e58f6ac0
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