diff --git a/drivers/net/wan/x25_asy.c b/drivers/net/wan/x25_asy.c
index 5895f19786919f6cfb36b97273a95bc1462d1c10..fa9fdfa128c1e6b732c74907fb43504c8ec2ad4c 100644
--- a/drivers/net/wan/x25_asy.c
+++ b/drivers/net/wan/x25_asy.c
@@ -122,8 +122,12 @@ static int x25_asy_change_mtu(struct net_device *dev, int newmtu)
 {
 	struct x25_asy *sl = netdev_priv(dev);
 	unsigned char *xbuff, *rbuff;
-	int len = 2 * newmtu;
+	int len;
 
+	if (newmtu > 65534)
+		return -EINVAL;
+
+	len = 2 * newmtu;
 	xbuff = kmalloc(len + 4, GFP_ATOMIC);
 	rbuff = kmalloc(len + 4, GFP_ATOMIC);