Automatic Update Failure

I’ve been trying to automatically update to 4.4.2 but ‘Installation Failed’ keeps being displayed.

The message that appears is:

Downloading update from http://downloads.wp.xz.cn/release/wordpress-4.4.2-new-bundled.zip…

Unpacking the update…

Verifying the unpacked files…

Preparing to install the latest version…

Enabling Maintenance mode…

Copying the required files…

Warning: copy(/var/www/html/crizo/xmlrpc.php) [function.copy]: failed to open stream: Permission denied in /var/www/html/crizo/wp-admin/includes/class-wp-filesystem-direct.php on line 200

Warning: copy(/var/www/html/crizo/xmlrpc.php) [function.copy]: failed to open stream: Permission denied in /var/www/html/crizo/wp-admin/includes/class-wp-filesystem-direct.php on line 200
Disabling Maintenance mode…

Could not copy file.: xmlrpc.php

Installation Failed

I know it’s something to do with permissions but can anyone tell me how to change permissions to get this working?