rtl818x: fix potential use after free

entry is released via usb_put_urb just after calling usb_submit_urb.
However, entry is used if the submission fails, resulting in a use after
free bug. The patch fixes this.
Signed-off-by: Pan Bian <bianpan2016@163.com>
ACKed-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c

@@ -444,12 +444,13 @@ static int rtl8187_init_urbs(struct ieee80211_hw *dev)
 		skb_queue_tail(&priv->rx_queue, skb);
 		usb_anchor_urb(entry, &priv->anchored);
 		ret = usb_submit_urb(entry, GFP_KERNEL);
-		usb_put_urb(entry);
 		if (ret) {
 			skb_unlink(skb, &priv->rx_queue);
 			usb_unanchor_urb(entry);
+			usb_put_urb(entry);
 			goto err;
 		}
+		usb_put_urb(entry);
 	}
 	return ret;