[PATCH] staging: emxx_udc: Add checks for dma_alloc_coherent()

[Yuan Can <yuancan@xxxxxxxxxx>]

As the dma_alloc_coherent() may return NULL, the return value needs to be
checked to avoid NULL poineter dereference.

Fixes: 33aa8d45a4fe ("staging: emxx_udc: Add Emma Mobile USB Gadget driver")
Signed-off-by: Yuan Can <yuancan@xxxxxxxxxx>
---
 drivers/staging/emxx_udc/emxx_udc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/staging/emxx_udc/emxx_udc.c b/drivers/staging/emxx_udc/emxx_udc.c
index b6abd3770e81..3c0c9c5eb733 100644
--- a/drivers/staging/emxx_udc/emxx_udc.c
+++ b/drivers/staging/emxx_udc/emxx_udc.c
@@ -2594,6 +2594,10 @@ static int nbu2ss_ep_queue(struct usb_ep *_ep,
 			ep->virt_buf = dma_alloc_coherent(udc->dev, PAGE_SIZE,
 							  &ep->phys_buf,
 							  GFP_ATOMIC | GFP_DMA);
+		if (!ep->virt_buf) {
+			spin_unlock_irqrestore(&udc->lock, flags);
+			return -ENOMEM;
+		}
 		if (ep->epnum > 0)  {
 			if (ep->direct == USB_DIR_IN)
 				memcpy(ep->virt_buf, req->req.buf,
-- 
2.17.1