usb: config->desc.bLength may not exceed amount of data returned by the device

commit b4f17a48 upstream.

While reading the config parsing code I noticed this check is missing, without
this check config->desc.wTotalLength can end up with a value larger then the
dev->rawdescriptors length for the config, and when userspace then tries to
get the rawdescriptors bad things may happen.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/usb/core/config.c

@@ -424,7 +424,8 @@ static int usb_parse_configuration(struct usb_device *dev, int cfgidx,
 
 	memcpy(&config->desc, buffer, USB_DT_CONFIG_SIZE);
 	if (config->desc.bDescriptorType != USB_DT_CONFIG ||
-	    config->desc.bLength < USB_DT_CONFIG_SIZE) {
+	    config->desc.bLength < USB_DT_CONFIG_SIZE ||
+	    config->desc.bLength > size) {
 		dev_err(ddev, "invalid descriptor for config index %d: "
 		    "type = 0x%X, length = %d\n", cfgidx,
 		    config->desc.bDescriptorType, config->desc.bLength);