Fix a potential NULL pointer dereference in write_bulk_callback() in drivers/net/usb/pegasus.c

This patch fixes a potential null dereference bug where we dereference
pegasus before a null check. This patch simply moves the dereferencing
after the null check.
Signed-off-by: NMicah Gruber <micah.gruber@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

drivers/net/usb/pegasus.c

@@ -768,11 +768,13 @@ static void rx_fixup(unsigned long data)
 static void write_bulk_callback(struct urb *urb)
 {
 	pegasus_t *pegasus = urb->context;
-	struct net_device *net = pegasus->net;
+	struct net_device *net;
 
 	if (!pegasus)
 		return;
 
+	net = pegasus->net;
+
 	if (!netif_device_present(net) || !netif_running(net))
 		return;