Bluetooth: Validate PSM values in calls to connect() and bind()

Valid L2CAP PSMs are odd numbers, and the least significant bit of the
most significant byte must be 0.
Signed-off-by: Mat Martineau <mathewm@codeaurora.org>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

net/bluetooth/l2cap.c

@@ -1008,10 +1008,20 @@ static int l2cap_sock_bind(struct socket *sock, struct sockaddr *addr, int alen)
 		goto done;
 	}
 
-	if (la.l2_psm && __le16_to_cpu(la.l2_psm) < 0x1001 &&
-				!capable(CAP_NET_BIND_SERVICE)) {
-		err = -EACCES;
-		goto done;
+	if (la.l2_psm) {
+		__u16 psm = __le16_to_cpu(la.l2_psm);
+
+		/* PSM must be odd and lsb of upper byte must be 0 */
+		if ((psm & 0x0101) != 0x0001) {
+			err = -EINVAL;
+			goto done;
+		}
+
+		/* Restrict usage of well-known PSMs */
+		if (psm < 0x1001 && !capable(CAP_NET_BIND_SERVICE)) {
+			err = -EACCES;
+			goto done;
+		}
 	}
 
 	write_lock_bh(&l2cap_sk_list.lock);
@@ -1190,6 +1200,13 @@ static int l2cap_sock_connect(struct socket *sock, struct sockaddr *addr, int al
 		goto done;
 	}
 
+	/* PSM must be odd and lsb of upper byte must be 0 */
+	if ((__le16_to_cpu(la.l2_psm) & 0x0101) != 0x0001 &&
+		sk->sk_type != SOCK_RAW) {
+		err = -EINVAL;
+		goto done;
+	}
+
 	/* Set destination address and psm */
 	bacpy(&bt_sk(sk)->dst, &la.l2_bdaddr);
 	l2cap_pi(sk)->psm = la.l2_psm;