Warning: preg_match(): Compilation failed

Logs get filled with error messages like:

Warning: preg_match(): Compilation failed: ... in _lazyloader_excluded_by_filename() (line 251 of .../lazyloader/lazyloader.module).

In code we see the line:

return (bool) preg_match('/^' . $filename . '$/m', $excluded_files);

It's easy to see that here is used unquoted variable $filename - regex injection.

Here is remedy:

return (bool) preg_match('/^' . preg_quote ($filename) . '$/m', $excluded_files);