USB: legousbtower: fix slab info leak at probe

Make sure to check for short transfers when retrieving the version
information at probe to avoid leaking uninitialised slab data when
logging it.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20190919083039.30898-2-johan@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/misc/legousbtower.c

@@ -891,8 +891,10 @@ static int tower_probe (struct usb_interface *interface, const struct usb_device
 				  get_version_reply,
 				  sizeof(*get_version_reply),
 				  1000);
-	if (result < 0) {
-		dev_err(idev, "LEGO USB Tower get version control request failed\n");
+	if (result < sizeof(*get_version_reply)) {
+		if (result >= 0)
+			result = -EIO;
+		dev_err(idev, "get version request failed: %d\n", result);
 		retval = result;
 		goto error;
 	}