linux-kernel - [PATCH] Bluetooth: L2CAP: fix "bad unlock balance" in l2cap_disconnect

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Message-Id: <20230417022754.4925-1-lm0963hack@gmail.com>
Date:   Mon, 17 Apr 2023 10:27:54 +0800
From:   Min Li <lm0963hack@...il.com>
To:     syzbot+9519d6b5b79cf7787cf3@...kaller.appspotmail.com
Cc:     davem@...emloft.net, edumazet@...gle.com, johan.hedberg@...il.com,
        kuba@...nel.org, linux-bluetooth@...r.kernel.org,
        linux-kernel@...r.kernel.org, luiz.dentz@...il.com,
        marcel@...tmann.org, netdev@...r.kernel.org, pabeni@...hat.com,
        syzkaller-bugs@...glegroups.com, Min Li <lm0963hack@...il.com>
Subject: [PATCH] Bluetooth: L2CAP: fix "bad unlock balance" in l2cap_disconnect_rsp

conn->chan_lock isn't acquired before l2cap_get_chan_by_scid,
if l2cap_get_chan_by_scid returns NULL, then 'bad unlock balance'
is triggered.

Reported-by: syzbot+9519d6b5b79cf7787cf3@...kaller.appspotmail.com
Link: https://lore.kernel.org/all/000000000000894f5f05f95e9f4d@google.com/
Signed-off-by: Min Li <lm0963hack@...il.com>
---
 net/bluetooth/l2cap_core.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 55a7226233f9..24d075282996 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -4694,7 +4694,6 @@ static inline int l2cap_disconnect_rsp(struct l2cap_conn *conn,
 
 	chan = l2cap_get_chan_by_scid(conn, scid);
 	if (!chan) {
-		mutex_unlock(&conn->chan_lock);
 		return 0;
 	}
 
-- 
2.25.1