USB: handle more rndis_host oddities

Workaround another device firmware bug, wherein CDC descriptors get
placed in a wrong place never previously observed in the wild.

Fix a bug where a seeming RNDIS device returns a bogus response during
device initialization.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/net/usb/cdc_ether.c

@@ -91,6 +91,22 @@ int usbnet_generic_cdc_bind(struct usbnet *dev, struct usb_interface *intf)
 				"CDC descriptors on config\n");
 	}
 
+	/* Maybe CDC descriptors are after the endpoint?  This bug has
+	 * been seen on some 2Wire Inc RNDIS-ish products.
+	 */
+	if (len == 0) {
+		struct usb_host_endpoint	*hep;
+
+		hep = intf->cur_altsetting->endpoint;
+		if (hep) {
+			buf = hep->extra;
+			len = hep->extralen;
+		}
+		if (len)
+			dev_dbg(&intf->dev,
+				"CDC descriptors on endpoint\n");
+	}
+
 	/* this assumes that if there's a non-RNDIS vendor variant
 	 * of cdc-acm, it'll fail RNDIS requests cleanly.
 	 */

drivers/net/usb/rndis_host.c

@@ -515,6 +515,7 @@ static int rndis_bind(struct usbnet *dev, struct usb_interface *intf)
 		dev_err(&intf->dev,
 			"dev can't take %u byte packets (max %u)\n",
 			dev->hard_mtu, tmp);
+		retval = -EINVAL;
 		goto fail_and_release;
 	}