Bluetooth: L2CAP: Fix use-after-free

jira VULN-155020
cve CVE-2023-53305
commit-author Zhengping Jiang <[email protected]>
commit f752a0b

Fix potential use-after-free in l2cap_le_command_rej.

	Signed-off-by: Zhengping Jiang <[email protected]>
	Signed-off-by: Luiz Augusto von Dentz <[email protected]>
	Signed-off-by: Jakub Kicinski <[email protected]>
(cherry picked from commit f752a0b)
	Signed-off-by: Shreeya Patel <[email protected]>

Author: shreeya-patel98

net/bluetooth/l2cap_core.c

@@ -6347,9 +6347,14 @@ static inline int l2cap_le_command_rej(struct l2cap_conn *conn,
 	if (!chan)
 		goto done;
 
+	chan = l2cap_chan_hold_unless_zero(chan);
+	if (!chan)
+		goto done;
+
 	l2cap_chan_lock(chan);
 	l2cap_chan_del(chan, ECONNREFUSED);
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 
 done:
 	mutex_unlock(&conn->chan_lock);