WARNING: locking bug in l2cap_sock_teardown_cb

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4143d798 Linux 4.19.165
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10f6b248d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=250ed6957c7993a3
dashboard link: https://syzkaller.appspot.com/bug?extid=a5d6afd52c7288b7d52c
compiler: gcc (GCC) 10.1.0-syz 20200507

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a5d6af...@syzkaller.appspotmail.com

EntryControls=0000d1ff ExitControls=002fefff
ExceptionBitmap=00060042 PFECmask=00000000 PFECmatch=00000000
VMEntry: intr_info=80000000 errcode=00000000 ilen=00000000
------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS)
WARNING: CPU: 1 PID: 33 at kernel/locking/lockdep.c:3392 __lock_acquire+0x1221/0x3ff0 kernel/locking/lockdep.c:3392
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 33 Comm: kworker/1:1 Not tainted 4.19.165-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+0x1fc/0x2fe lib/dump_stack.c:118
panic+0x26a/0x50e kernel/panic.c:186
__warn.cold+0x20/0x61 kernel/panic.c:541
report_bug+0x262/0x2b0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:178 [inline]
fixup_bug arch/x86/kernel/traps.c:173 [inline]
do_error_trap+0x1d7/0x310 arch/x86/kernel/traps.c:296
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1038
RIP: 0010:__lock_acquire+0x1221/0x3ff0 kernel/locking/lockdep.c:3392
Code: d2 0f 85 2d 1f 00 00 44 8b 3d cb 1f ea 0b 45 85 ff 0f 85 78 ef ff ff 48 c7 c6 40 43 6a 88 48 c7 c7 00 19 6a 88 e8 ea 57 ec ff <0f> 0b e9 61 ef ff ff 8b 05 82 61 d7 0b 85 c0 0f 85 4e f9 ff ff 4c
RSP: 0018:ffff8880b5117930 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000000000000009 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff814fdd11 RDI: ffffed1016a22f18
RBP: ffff8880b510aa8a R08: 0000000000000000 R09: 0000000000000ce1
R10: 0000000000000006 R11: ffffffff8c65d05b R12: 0000000000040969
R13: ffff8880b510a140 R14: ffff8880b510aa80 R15: 0000000000000000
lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3907
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:168
spin_lock_bh include/linux/spinlock.h:334 [inline]
lock_sock_nested+0x3b/0x110 net/core/sock.c:2864
l2cap_sock_teardown_cb+0xa0/0x6d0 net/bluetooth/l2cap_sock.c:1340
l2cap_chan_del+0xbc/0xa50 net/bluetooth/l2cap_core.c:599
l2cap_chan_close+0x1b5/0x950 net/bluetooth/l2cap_core.c:757
l2cap_chan_timeout+0x17e/0x2f0 net/bluetooth/l2cap_core.c:430
process_one_work+0x864/0x1570 kernel/workqueue.c:2155
worker_thread+0x64c/0x1130 kernel/workqueue.c:2298
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.