usb: dwc3: gadget: Fix null pointer exception

In the endpoint interrupt functions dwc3_gadget_endpoint_transfer_in_progress() and dwc3_gadget_endpoint_trbs_complete() will dereference the endpoint descriptor. But it could be cleared in __dwc3_gadget_ep_disable() when accessory disconnected. So we need to check whether it is null or not before dereferencing it.

---
Changelog since v3:
- Put 'Signed-off-by' in the bottom line

Changelog since v2:
- Add 'Fixes' message
- Add 'Reviewed-by' message

Changelog since v1:
- Add null pointer check in dwc3_gadget_endpoint_trbs_complete()
- Add null pointer check in dwc3_gadget_endpoint_transfer_in_progress()

 drivers/usb/dwc3/gadget.c | 6 ++++++
 1 file changed, 6 insertions(+)

index 23de2a5a40d6..83c7344888fd 100644
@@ -3252,6 +3252,9 @@ static bool dwc3_gadget_endpoint_trbs_complete(struct dwc3_ep *dep,
 	struct dwc3		*dwc = dep->dwc;
 	bool			no_started_trb = true;
 
+	if (!dep->endpoint.desc)
+		return no_started_trb;
+
 	dwc3_gadget_ep_cleanup_completed_requests(dep, event, status);
 
 	if (dep->flags & DWC3_EP_END_TRANSFER_PENDING)

@@ -3299,6 +3302,9 @@ static void dwc3_gadget_endpoint_transfer_in_progress(struct dwc3_ep *dep,
 {
 	int status = 0;
 
+	if (!dep->endpoint.desc)
+		return;
+
 	if (usb_endpoint_xfer_isoc(dep->endpoint.desc))
 		dwc3_gadget_endpoint_frame_from_event(dep, event);
 

2.34.0.rc0.344.g81b53c2807-goog