[PATCH] usb: cdns3: Handle ZLP request allocation failure

[Triet Hoang <triet.hoang.dev@gmail.com>]

From: Triet Hoang <triet.hoang.dev@gmail.com>

Check the return value of cdns3_gadget_ep_alloc_request() before
dereferencing the returned request.

Signed-off-by: Triet Hoang <triet.hoang.dev@gmail.com>
---
Changes in v2:
- Allocate the ZLP request before queuing the primary request.
- Free the allocated ZLP request when the primary request queueing fails.

Changes in v3:
- Move patch version descriptions below the '---' marker.

 drivers/usb/cdns3/cdns3-gadget.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
index 42311c1bfada..05d225f99012 100644
--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -2641,7 +2641,7 @@ static int __cdns3_gadget_ep_queue(struct usb_ep *ep,
 static int cdns3_gadget_ep_queue(struct usb_ep *ep, struct usb_request *request,
 				 gfp_t gfp_flags)
 {
-	struct usb_request *zlp_request;
+	struct usb_request *zlp_request = NULL;
 	struct cdns3_endpoint *priv_ep;
 	struct cdns3_device *priv_dev;
 	unsigned long flags;
@@ -2655,24 +2655,36 @@ static int cdns3_gadget_ep_queue(struct usb_ep *ep, struct usb_request *request,
 
 	spin_lock_irqsave(&priv_dev->lock, flags);
 
-	ret = __cdns3_gadget_ep_queue(ep, request, gfp_flags);
-
-	if (ret == 0 && request->zero && request->length &&
+	if (request->zero && request->length &&
 	    (request->length % ep->maxpacket == 0)) {
 		struct cdns3_request *priv_req;
 
 		zlp_request = cdns3_gadget_ep_alloc_request(ep, GFP_ATOMIC);
+		if (!zlp_request) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
 		zlp_request->buf = priv_dev->zlp_buf;
 		zlp_request->length = 0;
 
 		priv_req = to_cdns3_request(zlp_request);
 		priv_req->flags |= REQUEST_ZLP;
+	}
+
+	ret = __cdns3_gadget_ep_queue(ep, request, gfp_flags);
+	if (ret)
+		goto out;
 
+	if (zlp_request) {
 		dev_dbg(priv_dev->dev, "Queuing ZLP for endpoint: %s\n",
 			priv_ep->name);
 		ret = __cdns3_gadget_ep_queue(ep, zlp_request, gfp_flags);
 	}
 
+out:
+	if (ret && zlp_request)
+		cdns3_gadget_ep_free_request(ep, zlp_request);
 	spin_unlock_irqrestore(&priv_dev->lock, flags);
 	return ret;
 }
-- 
2.53.0