Re: [syzbot] possible deadlock in sco_conn_del

From: syzbot
Date: Mon Apr 11 2022 - 19:37:15 EST

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Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in sco_conn_del

======================================================
WARNING: possible circular locking dependency detected
5.18.0-rc1-next-20220411-syzkaller-dirty #0 Not tainted
------------------------------------------------------
syz-executor129/4082 is trying to acquire lock:
ffff88807c11d130 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1682 [inline]
ffff88807c11d130 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_conn_del+0x131/0x2c0 net/bluetooth/sco.c:197

but task is already holding lock:
ffffffff8d777e08 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1580 [inline]
ffffffff8d777e08 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xda/0x260 net/bluetooth/hci_conn.c:1458

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (hci_cb_list_lock){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747
hci_connect_cfm+0x26/0x140 include/net/bluetooth/hci_core.h:1565
le_conn_complete_evt.part.0+0x145e/0x17e0 net/bluetooth/hci_event.c:5666
le_conn_complete_evt net/bluetooth/hci_event.c:5692 [inline]
hci_le_conn_complete_evt+0x2fd/0x390 net/bluetooth/hci_event.c:5692
hci_le_meta_evt+0x2bd/0x520 net/bluetooth/hci_event.c:6559
hci_event_func net/bluetooth/hci_event.c:6889 [inline]
hci_event_packet+0x5da/0xf60 net/bluetooth/hci_event.c:6941
hci_rx_work+0x522/0xd60 net/bluetooth/hci_core.c:3819
process_one_work+0x996/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

-> #1 (&hdev->lock){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747
sco_sock_connect+0x1eb/0xa80 net/bluetooth/sco.c:593
__sys_connect_file+0x14f/0x190 net/socket.c:1900
__sys_connect+0x161/0x190 net/socket.c:1917
__do_sys_connect net/socket.c:1927 [inline]
__se_sys_connect net/socket.c:1924 [inline]
__x64_sys_connect+0x6f/0xb0 net/socket.c:1924
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3095 [inline]
check_prevs_add kernel/locking/lockdep.c:3214 [inline]
validate_chain kernel/locking/lockdep.c:3829 [inline]
__lock_acquire+0x2abe/0x5660 kernel/locking/lockdep.c:5053
lock_acquire kernel/locking/lockdep.c:5665 [inline]
lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5630
lock_sock_nested+0x36/0xf0 net/core/sock.c:3314
lock_sock include/net/sock.h:1682 [inline]
sco_conn_del+0x131/0x2c0 net/bluetooth/sco.c:197
sco_disconn_cfm+0x71/0xb0 net/bluetooth/sco.c:1379
hci_disconn_cfm include/net/bluetooth/hci_core.h:1583 [inline]
hci_conn_hash_flush+0x127/0x260 net/bluetooth/hci_conn.c:1458
hci_dev_close_sync+0x567/0x1140 net/bluetooth/hci_sync.c:4152
hci_dev_do_close+0x32/0x70 net/bluetooth/hci_core.c:553
hci_rfkill_set_block+0x19c/0x1d0 net/bluetooth/hci_core.c:935
rfkill_set_block+0x1f9/0x540 net/rfkill/core.c:345
rfkill_fop_write+0x2c3/0x570 net/rfkill/core.c:1286
vfs_write+0x269/0xac0 fs/read_write.c:589
ksys_write+0x1e8/0x250 fs/read_write.c:644
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

other info that might help us debug this:

Chain exists of:
sk_lock-AF_BLUETOOTH-BTPROTO_SCO --> &hdev->lock --> hci_cb_list_lock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(hci_cb_list_lock);
lock(&hdev->lock);
lock(hci_cb_list_lock);
lock(sk_lock-AF_BLUETOOTH-BTPROTO_SCO);

*** DEADLOCK ***

4 locks held by syz-executor129/4082:
#0: ffffffff8d9583a8 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_fop_write+0x15c/0x570 net/rfkill/core.c:1278
#1: ffff88801f891048 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x2a/0x70 net/bluetooth/hci_core.c:551
#2: ffff88801f890078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_close_sync+0x26d/0x1140 net/bluetooth/hci_sync.c:4139
#3: ffffffff8d777e08 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1580 [inline]
#3: ffffffff8d777e08 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xda/0x260 net/bluetooth/hci_conn.c:1458

stack backtrace:
CPU: 1 PID: 4082 Comm: syz-executor129 Not tainted 5.18.0-rc1-next-20220411-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2175
check_prev_add kernel/locking/lockdep.c:3095 [inline]
check_prevs_add kernel/locking/lockdep.c:3214 [inline]
validate_chain kernel/locking/lockdep.c:3829 [inline]
__lock_acquire+0x2abe/0x5660 kernel/locking/lockdep.c:5053
lock_acquire kernel/locking/lockdep.c:5665 [inline]
lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5630
lock_sock_nested+0x36/0xf0 net/core/sock.c:3314
lock_sock include/net/sock.h:1682 [inline]
sco_conn_del+0x131/0x2c0 net/bluetooth/sco.c:197
sco_disconn_cfm+0x71/0xb0 net/bluetooth/sco.c:1379
hci_disconn_cfm include/net/bluetooth/hci_core.h:1583 [inline]
hci_conn_hash_flush+0x127/0x260 net/bluetooth/hci_conn.c:1458
hci_dev_close_sync+0x567/0x1140 net/bluetooth/hci_sync.c:4152
hci_dev_do_close+0x32/0x70 net/bluetooth/hci_core.c:553
hci_rfkill_set_block+0x19c/0x1d0 net/bluetooth/hci_core.c:935
rfkill_set_block+0x1f9/0x540 net/rfkill/core.c:345
rfkill_fop_write+0x2c3/0x570 net/rfkill/core.c:1286
vfs_write+0x269/0xac0 fs/read_write.c:589
ksys_write+0x1e8/0x250 fs/read_write.c:644
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fab5d4df609
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 d1 15 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fab5cc8e2f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fab5d5684c0 RCX: 00007fab5d4df609
RDX: 0000000000000008 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffeea3e1ffe
R13: 00007ffeea3e1fff R14: 00007fab5d5684c8 R15: 0000000000022000
</TASK>

Tested on:

commit: d12d7e1c Add linux-next specific files for 20220411
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/
console output: https://syzkaller.appspot.com/x/log.txt?x=14908904f00000
kernel config: https://syzkaller.appspot.com/x/.config?x=58fcaf7d8df169a6
dashboard link: https://syzkaller.appspot.com/bug?extid=b825d87fe2d043e3e652
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch: https://syzkaller.appspot.com/x/patch.diff?x=16223d2f700000

Next message: Dmitry Osipenko: "[PATCH v7 00/20] Introduce power-off+restart call chain API"
Previous message: Luck, Tony: "[PATCH] x86/cpu: Add new Alderlake and Raptorlake CPU model numbers"
In reply to: syzbot: "Re: [syzbot] possible deadlock in sco_conn_del"
Next in thread: syzbot: "Re: [syzbot] possible deadlock in sco_conn_del"
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