WARNING: locking bug in l2cap_sock_teardown

WARNING: locking bug in l2cap_sock_teardown_cb
Status: upstream: reported on 2021/01/08 18:15
Reported-by: syzbot+a5d6afd52c7288b7d52c@syzkaller.appspotmail.com
First crash: 121d, last: 97d

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
linux-4.14	WARNING: locking bug in l2cap_sock_teardown_cb				2	17d	56d	0/1	upstream: reported on 2021/03/15 06:29
upstream	WARNING: locking bug in l2cap_sock_teardown_cb				95	4d06h	124d	0/22	upstream: reported on 2021/01/05 11:03

Sample crash report:

------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS)
WARNING: CPU: 0 PID: 4589 at kernel/locking/lockdep.c:3392 __lock_acquire+0x1221/0x3ff0 kernel/locking/lockdep.c:3392
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 4589 Comm: syz-executor.3 Not tainted 4.19.172-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
 panic+0x26a/0x50e kernel/panic.c:186
 __warn.cold+0x20/0x5a 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 bb 88 eb 0b 45 85 ff 0f 85 78 ef ff ff 48 c7 c6 80 43 6a 88 48 c7 c7 40 19 6a 88 e8 94 b0 a4 06 <0f> 0b e9 61 ef ff ff 8b 05 72 ca d8 0b 85 c0 0f 85 4e f9 ff ff 4c
RSP: 0018:ffff888075aa7520 EFLAGS: 00010086
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff814de0d1 RDI: ffffed100eb54e96
RBP: ffff88805f0a8e32 R08: 0000000000000000 R09: 0000000000001f71
R10: 0000000000000006 R11: ffffffff8c65d01b R12: 000000000004033d
R13: ffff88805f0a84c0 R14: ffff88805f0a8e28 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_conn_del+0x3a6/0x6e0 net/bluetooth/l2cap_core.c:1729
 l2cap_disconn_cfm net/bluetooth/l2cap_core.c:7441 [inline]
 l2cap_disconn_cfm+0x98/0xd0 net/bluetooth/l2cap_core.c:7434
 hci_disconn_cfm include/net/bluetooth/hci_core.h:1261 [inline]
 hci_conn_hash_flush+0x127/0x260 net/bluetooth/hci_conn.c:1512
 hci_dev_do_close+0x659/0xf10 net/bluetooth/hci_core.c:1666
 hci_unregister_dev+0x18b/0x910 net/bluetooth/hci_core.c:3271
 vhci_release+0x70/0xe0 drivers/bluetooth/hci_vhci.c:354
 __fput+0x2ce/0x890 fs/file_table.c:278
 task_work_run+0x148/0x1c0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0xbf3/0x2be0 kernel/exit.c:870
 do_group_exit+0x125/0x310 kernel/exit.c:967
 get_signal+0x3f2/0x1f70 kernel/signal.c:2589
 do_signal+0x8f/0x1670 arch/x86/kernel/signal.c:821
 exit_to_usermode_loop+0x204/0x2a0 arch/x86/entry/common.c:163
 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
 do_syscall_64+0x538/0x620 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x465b09
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f57f809e218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000056bf68 RCX: 0000000000465b09
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000056bf68
RBP: 000000000056bf60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf6c
R13: 00007ffc56e8e0ff R14: 00007f57f809e300 R15: 0000000000022000
Kernel Offset: disabled
Rebooting in 86400 seconds..

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-linux-4-19	2021/02/02 08:54	linux-4.19.y	811218ec	19e09687	.config	log	report			info	WARNING: locking bug in l2cap_sock_teardown_cb
ci2-linux-4-19	2021/01/08 18:14	linux-4.19.y	4143d798	c104d4a3	.config	log	report			info