Re: INFO: trying to register non-static key in l2cap_chan_del

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    4c900a6b farsync: switch from 'pci_' to 'dma_' API
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1561801a900000
kernel config:  https://syzkaller.appspot.com/x/.config?x=91a13b78c7dc258d
dashboard link: https://syzkaller.appspot.com/bug?extid=abfc0f5e668d4099af73
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15bdcc3a900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+abfc0f5e668d4099af73@xxxxxxxxxxxxxxxxxxxxxxxxx

INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.8.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events l2cap_chan_timeout
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 assign_lock_key kernel/locking/lockdep.c:894 [inline]
 register_lock_class+0x157d/0x1630 kernel/locking/lockdep.c:1206
 __lock_acquire+0xfa/0x56e0 kernel/locking/lockdep.c:4259
 lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:4959
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
 _raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:175
 spin_lock_bh include/linux/spinlock.h:358 [inline]
 lock_sock_nested+0x3b/0x110 net/core/sock.c:3019
 l2cap_sock_teardown_cb+0x88/0x400 net/bluetooth/l2cap_sock.c:1520
 l2cap_chan_del+0xad/0x1300 net/bluetooth/l2cap_core.c:618
 l2cap_chan_close+0x118/0xb10 net/bluetooth/l2cap_core.c:823
 l2cap_chan_timeout+0x173/0x450 net/bluetooth/l2cap_core.c:436
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 0 P4D 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.8.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events l2cap_chan_timeout
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffffc90000cbfb60 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff8880931bd000 RCX: ffffffff8728bc2f
RDX: 1ffff11014549a8c RSI: ffffffff8728be7c RDI: ffff8880a2a4d000
RBP: 0000000000000005 R08: 0000000000000001 R09: ffff8880a2a4d067
R10: 0000000000000009 R11: 0000000000000001 R12: 000000000000006f
R13: ffff8880a2a4d000 R14: 0000000000000000 R15: 0000000000000005
FS:  0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000929e6000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 l2cap_sock_teardown_cb+0x374/0x400 net/bluetooth/l2cap_sock.c:1547
 l2cap_chan_del+0xad/0x1300 net/bluetooth/l2cap_core.c:618
 l2cap_chan_close+0x118/0xb10 net/bluetooth/l2cap_core.c:823
 l2cap_chan_timeout+0x173/0x450 net/bluetooth/l2cap_core.c:436
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
Modules linked in:
CR2: 0000000000000000
---[ end trace ecb0577583d92fc1 ]---
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffffc90000cbfb60 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff8880931bd000 RCX: ffffffff8728bc2f
RDX: 1ffff11014549a8c RSI: ffffffff8728be7c RDI: ffff8880a2a4d000
RBP: 0000000000000005 R08: 0000000000000001 R09: ffff8880a2a4d067
R10: 0000000000000009 R11: 0000000000000001 R12: 000000000000006f
R13: ffff8880a2a4d000 R14: 0000000000000000 R15: 0000000000000005
FS:  0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000929e6000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400