usb: gadget: don't leak configs when unbinding

By the time g_dnl_unbind() is run, cdev->config has been set to NULL,
so the free() there does nothing, and the config struct is leaked.
Equally, struct usb_gadget contains a linked list of config structs, so
the code should iterate over them all and free each one, rather than
freeing one particular config struct.

composite_unbind() already iterates over the list of config structs, and
unlinks each from the linked list. Fix this loop to free() each struct as
it's unlinked and otherwise forgotten.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Lukasz Majewski <l.majewski@samsung.com>
Tested-by: Lukasz Majewski <l.majewski@samsung.com>

drivers/usb/gadget/composite.c

@@ -948,6 +948,7 @@ static void composite_unbind(struct usb_gadget *gadget)
 			debug("unbind config '%s'/%p\n", c->label, c);
 			c->unbind(c);
 		}
+		free(c);
 	}
 	if (composite->unbind)
 		composite->unbind(cdev);

drivers/usb/gadget/g_dnl.c

@@ -93,8 +93,6 @@ static int g_dnl_unbind(struct usb_composite_dev *cdev)
 {
 	struct usb_gadget *gadget = cdev->gadget;
 
-	free(cdev->config);
-	cdev->config = NULL;
 	debug("%s: calling usb_gadget_disconnect for "
 			"controller '%s'\n", __func__, gadget->name);
 	usb_gadget_disconnect(gadget);