function change_image_link($content) {

    global $product;

    $product_link = '<a href="' . $product->get_product_url();

    $content = preg_replace('/(<a href=\")([^\"]*)/i', $product_link, $content);

return $content;

}

add_filter('woocommerce_single_product_image_html', 'change_image_link');