rtl8xxxu: Check return value of kmemdup()

In rtl8xxxu_load_firmware() check the return value of kmemdup() and
error out with -ENOMEM in case of NULL to prevent a NULL pointer
dereference.
Signed-off-by: NTobias Klauser <tklauser@distanz.ch>
Signed-off-by: NJes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.c

@@ -2197,6 +2197,10 @@ static int rtl8xxxu_load_firmware(struct rtl8xxxu_priv *priv, char *fw_name)
 	}
 
 	priv->fw_data = kmemdup(fw->data, fw->size, GFP_KERNEL);
+	if (!priv->fw_data) {
+		ret = -ENOMEM;
+		goto exit;
+	}
 	priv->fw_size = fw->size - sizeof(struct rtl8xxxu_firmware_header);
 
 	signature = le16_to_cpu(priv->fw_data->signature);