usb: gadget: aspeed: remove usage of list iterator past the loop body

If the list representing the request queue does not contain the expected
request, the value of the list_for_each_entry() iterator will not point
to a valid structure. To avoid type confusion in such case, the list
iterator scope will be limited to the list_for_each_entry() loop.

In preparation to limiting scope of the list iterator to the list traversal
loop, use a dedicated pointer to point to the found request object [1].

Link: https://lore.kernel.org/all/YhdfEIwI4EdtHdym@kroah.com/
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
Link: https://lore.kernel.org/r/20220308171818.384491-17-jakobkoschel@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/aspeed-vhub/epn.c

@@ -466,19 +466,21 @@ static int ast_vhub_epn_dequeue(struct usb_ep* u_ep, struct usb_request *u_req)
 {
 	struct ast_vhub_ep *ep = to_ast_ep(u_ep);
 	struct ast_vhub *vhub = ep->vhub;
-	struct ast_vhub_req *req;
+	struct ast_vhub_req *req = NULL, *iter;
 	unsigned long flags;
 	int rc = -EINVAL;
 
 	spin_lock_irqsave(&vhub->lock, flags);
 
 	/* Make sure it's actually queued on this endpoint */
-	list_for_each_entry (req, &ep->queue, queue) {
-		if (&req->req == u_req)
-			break;
+	list_for_each_entry(iter, &ep->queue, queue) {
+		if (&iter->req != u_req)
+			continue;
+		req = iter;
+		break;
 	}
 
-	if (&req->req == u_req) {
+	if (req) {
 		EPVDBG(ep, "dequeue req @%p active=%d\n",
 		       req, req->active);
 		if (req->active)