pptp: verify sockaddr_len in pptp_bind() and pptp_connect()

commit 09ccfd23 upstream.
Reported-by: Dmitry Vyukov <dvyukov@gmail.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Zefan Li <lizefan@huawei.com>

drivers/net/ppp/pptp.c

@@ -420,6 +420,9 @@ static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
 	struct pptp_opt *opt = &po->proto.pptp;
 	int error = 0;
 
+	if (sockaddr_len < sizeof(struct sockaddr_pppox))
+		return -EINVAL;
+
 	lock_sock(sk);
 
 	opt->src_addr = sp->sa_addr.pptp;
@@ -441,6 +444,9 @@ static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
 	struct flowi4 fl4;
 	int error = 0;
 
+	if (sockaddr_len < sizeof(struct sockaddr_pppox))
+		return -EINVAL;
+
 	if (sp->sa_protocol != PX_PROTO_PPTP)
 		return -EINVAL;