usb: gadget: lpc32xx_udc: don't dereference ep pointer before null check

BugLink: https://bugs.launchpad.net/bugs/1885932

[ Upstream commit eafa8004 ]

Currently pointer ep is being dereferenced before it is null checked
leading to a null pointer dereference issue.  Fix this by only assigning
pointer udc once ep is known to be not null.  Also remove a debug
message that requires a valid udc which may not be possible at that
point.

Addresses-Coverity: ("Dereference before null check")
Fixes: 24a28e42 ("USB: gadget driver for LPC32xx")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

drivers/usb/gadget/udc/lpc32xx_udc.c

@@ -1662,17 +1662,17 @@ static int lpc32xx_ep_enable(struct usb_ep *_ep,
 			     const struct usb_endpoint_descriptor *desc)
 {
 	struct lpc32xx_ep *ep = container_of(_ep, struct lpc32xx_ep, ep);
-	struct lpc32xx_udc *udc = ep->udc;
+	struct lpc32xx_udc *udc;
 	u16 maxpacket;
 	u32 tmp;
 	unsigned long flags;
 
 	/* Verify EP data */
 	if ((!_ep) || (!ep) || (!desc) ||
-	    (desc->bDescriptorType != USB_DT_ENDPOINT)) {
-		dev_dbg(udc->dev, "bad ep or descriptor\n");
+	    (desc->bDescriptorType != USB_DT_ENDPOINT))
 		return -EINVAL;
-	}
+
+	udc = ep->udc;
 	maxpacket = usb_endpoint_maxp(desc);
 	if ((maxpacket == 0) || (maxpacket > ep->maxpacket)) {
 		dev_dbg(udc->dev, "bad ep descriptor's packet size\n");
@@ -1920,7 +1920,7 @@ static int lpc32xx_ep_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 static int lpc32xx_ep_set_halt(struct usb_ep *_ep, int value)
 {
 	struct lpc32xx_ep *ep = container_of(_ep, struct lpc32xx_ep, ep);
-	struct lpc32xx_udc *udc = ep->udc;
+	struct lpc32xx_udc *udc;
 	unsigned long flags;
 
 	if ((!ep) || (ep->hwep_num <= 1))
@@ -1930,6 +1930,7 @@ static int lpc32xx_ep_set_halt(struct usb_ep *_ep, int value)
 	if (ep->is_in)
 		return -EAGAIN;
 
+	udc = ep->udc;
 	spin_lock_irqsave(&udc->lock, flags);
 
 	if (value == 1) {