[PATCH] net/usb: Misc. fixes for the LG-VL600 LTE USB modem

[Mark Kamichoff <prox@prolixium.com>]

Add checking for valid magic values (needed for stability in the event
corrupted packets are received) and remove some other unneeded checks.
Also, fix flagging device as WWAN (Bugzilla bug #39952).

Signed-off-by: Mark Kamichoff <prox@prolixium.com>
---
 drivers/net/usb/cdc_ether.c |    2 +-
 drivers/net/usb/lg-vl600.c  |   30 ++++++++++++++----------------
 2 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/drivers/net/usb/cdc_ether.c b/drivers/net/usb/cdc_ether.c
index c924ea2..99ed6eb 100644
--- a/drivers/net/usb/cdc_ether.c
+++ b/drivers/net/usb/cdc_ether.c
@@ -567,7 +567,7 @@ static const struct usb_device_id	products [] = {
 {
 	USB_DEVICE_AND_INTERFACE_INFO(0x1004, 0x61aa, USB_CLASS_COMM,
 			USB_CDC_SUBCLASS_ETHERNET, USB_CDC_PROTO_NONE),
-	.driver_info = (unsigned long)&wwan_info,
+	.driver_info = 0,
 },
 
 /*
diff --git a/drivers/net/usb/lg-vl600.c b/drivers/net/usb/lg-vl600.c
index d43db32..b975a39 100644
--- a/drivers/net/usb/lg-vl600.c
+++ b/drivers/net/usb/lg-vl600.c
@@ -144,10 +144,11 @@ static int vl600_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 	}
 
 	frame = (struct vl600_frame_hdr *) buf->data;
-	/* NOTE: Should check that frame->magic == 0x53544448?
-	 * Otherwise if we receive garbage at the beginning of the frame
-	 * we may end up allocating a huge buffer and saving all the
-	 * future incoming data into it.  */
+	/* Yes, check that frame->magic == 0x53544448 (or 0x44544d48),
+	 * otherwise we may run out of memory w/a bad packet */
+	if (ntohl(frame->magic) != 0x53544448 &&
+			ntohl(frame->magic) != 0x44544d48)
+		goto error;
 
 	if (buf->len < sizeof(*frame) ||
 			buf->len != le32_to_cpup(&frame->len)) {
@@ -209,8 +210,9 @@ static int vl600_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 			 * for IPv6 packets, and set the ethertype to IPv6
 			 * (0x86dd) so Linux can understand it.
 			 */
-			if ((buf->data[sizeof(*ethhdr)] & 0xf0) == 0x60)
-				ethhdr->h_proto = __constant_htons(ETH_P_IPV6);
+			if ((buf->data[sizeof(*ethhdr)] & 0xf0) == 0x60) {
+				ethhdr->h_proto = htons(ETH_P_IPV6);
+			}
 		}
 
 		if (count) {
@@ -296,6 +298,11 @@ encapsulate:
 	 * overwrite the remaining fields.
 	 */
 	packet = (struct vl600_pkt_hdr *) skb->data;
+	/* The VL600 wants IPv6 packets to have an IPv4 ethertype
+	 * Since this modem only supports IPv4 and IPv6, just set all
+	 * frames to 0x0800 (ETH_P_IP)
+	 */
+	packet->h_proto = htons(ETH_P_IP);
 	memset(&packet->dummy, 0, sizeof(packet->dummy));
 	packet->len = cpu_to_le32(orig_len);
 
@@ -308,21 +315,12 @@ encapsulate:
 	if (skb->len < full_len) /* Pad */
 		skb_put(skb, full_len - skb->len);
 
-	/* The VL600 wants IPv6 packets to have an IPv4 ethertype
-	 * Check if this is an IPv6 packet, and set the ethertype
-	 * to 0x800
-	 */
-	if ((skb->data[sizeof(struct vl600_pkt_hdr *) + 0x22] & 0xf0) == 0x60) {
-		skb->data[sizeof(struct vl600_pkt_hdr *) + 0x20] = 0x08;
-		skb->data[sizeof(struct vl600_pkt_hdr *) + 0x21] = 0;
-	}
-
 	return skb;
 }
 
 static const struct driver_info	vl600_info = {
 	.description	= "LG VL600 modem",
-	.flags		= FLAG_ETHER | FLAG_RX_ASSEMBLE,
+	.flags		= FLAG_RX_ASSEMBLE | FLAG_WWAN,
 	.bind		= vl600_bind,
 	.unbind		= vl600_unbind,
 	.status		= usbnet_cdc_status,
-- 
1.7.5.4