can: mscan: fix improper return if dlc < 8 in start_xmit function

The start_xmit function of the MSCAN Driver did return improperly if
the CAN dlc check failed (skb not freed and invalid return code). This
patch adds a proper check of the frame lenght and data size and returns
now correctly. The invalid skb packets are dropped silently as suggested
by David Miller in the thread "[RFC] ndo_validate_skb: Let the netdev
check a valid skb content" on the netdev mailing list.

Furthermore, a typo has been fixed.
Signed-off-by: Wolfgang Grandegger <wg@denx.de>
Reviewed-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/can/mscan/mscan.c

@@ -4,7 +4,7 @@
  * Copyright (C) 2005-2006 Andrey Volkov <avolkov@varma-el.com>,
  *                         Varma Electronics Oy
  * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
- * Copytight (C) 2008-2009 Pengutronix <kernel@pengutronix.de>
+ * Copyright (C) 2008-2009 Pengutronix <kernel@pengutronix.de>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the version 2 of the GNU General Public License
@@ -177,8 +177,11 @@ static netdev_tx_t mscan_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	int i, rtr, buf_id;
 	u32 can_id;
 
-	if (frame->can_dlc > 8)
-		return -EINVAL;
+	if (skb->len != sizeof(*frame) || frame->can_dlc > 8) {
+		kfree_skb(skb);
+		dev->stats.tx_dropped++;
+		return NETDEV_TX_OK;
+	}
 
 	out_8(&regs->cantier, 0);