Ticket #43: libusb.diff

libusb/descriptor.c

@@ -681 +681 @@
         /* Asking for the zero'th index is special - it returns a string
          * descriptor that contains all the language IDs supported by the device.
          * Typically there aren't many - often only one. The language IDs are 16
-         * bit numbers, and they start at the third byte in the descriptor. See
-         * USB 2.0 specification section 9.6.7 for more information. */
+         * bit numbers, and they start at the third byte in the descriptor. This
+         * also make useless fetch zero index by this function. See USB 2.0
+         * specification section 9.6.7 for more information. */
+
+        if (desc_index == 0)
+                return LIBUSB_ERROR_INVALID_PARAM;
+
         r = libusb_get_string_descriptor(dev, 0, 0, tbuf, sizeof(tbuf));
         if (r < 0)
                 return r;