usb: gadget: composite: avoid access beyond array max length

One of the USB CV MSC tests issues Get Max LUN request with
invalid wIndex (wIndex = 65535) parameter.

Add proper handling to prevent array index out of bounds issue.

Signed-off-by: Maulik Mankad <[e-mail]>
Cc: David Brownell <[e-mail]>
Acked-by: Alan Stern <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/gadget/composite.c

···
 		 */
 		switch (ctrl->bRequestType & USB_RECIP_MASK) {
 		case USB_RECIP_INTERFACE:
-			if (cdev->config)
-				f = cdev->config->interface[intf];
+			if (!cdev->config || w_index >= MAX_CONFIG_INTERFACES)
+				break;
+			f = cdev->config->interface[intf];
 			break;
 
 		case USB_RECIP_ENDPOINT: