title: ModSecurity maximum post limits (PCRE limit errors)
body: <p>I've been having tonnes of issues with Mod Security. I am busy writing a CMS for a project at work and while developing a page to edit a certain database record I kept getting 403 errors. After hours of banging my head against my desk, adjusting bits of code I finally just changed the script to which my form was being posted, to contain a simple <code>echo "test";</code>. Even submitting to this simple page was kicking up a 403 error. I messed about with my form and I eventually found that if I reduced the amount of data I was posting the form submitted fine (In particular I reduce the amount of text within a textarea).</p>
  
  <p>After checking the logs (Yep, this wasn't the first thing I did - sigh) I noticed that I was getting numerous errors from ModSecurity, such as:</p>
  
  <pre><code>[Mon Aug 12 16:34:45 2013] [error] [client XX.XXX.XXX.XXX] ModSecurity: Failed to access DBM file "/etc/httpd/logs//global": Permission denied [hostname "XXXXXXX.XXX"] [uri "/admin/index.php"] [unique_id "UgkAlW1shFcAAHTMK80AAAAF"]
  [Mon Aug 12 16:34:45 2013] [error] [client XX.XXX.XXX.XXX] ModSecurity: Failed to access DBM file "/etc/httpd/logs//ip": Permission denied [hostname "XXXXXXX.XXX"] [uri "/admin/index.php"] [unique_id "UgkAlW1shFcAAHTMK80AAAAF"]
  [Mon Aug 12 17:11:33 2013] [error] [client XX.XXX.XXX.XXX] ModSecurity: Rule execution error - PCRE limits exceeded (-8): (null). [hostname "XXXXXXX.XXX"] [uri "/admin/index.php"] [unique_id "UgkJNW1shFcAAHXUMHkAAAAH"]
  [Mon Aug 12 17:11:33 2013] [error] [client XX.XXX.XXX.XXX] ModSecurity: Access denied with code 403 (phase 2). Match of "streq 0" against "TX:MSC_PCRE_LIMITS_EXCEEDED" required. [file "/etc/httpd/conf.d/mod_security.conf"] [line "93"] [msg "ModSecurity internal error flagged: TX:MSC_PCRE_LIMITS_EXCEEDED"] [hostname "XXXXXXX.XXX"] [uri "/admin/index.php"] [unique_id "UgkJNW1shFcAAHXUMHkAAAAH"]
  </code></pre>
  
  <p>I've been messing around, Googling and changing rules for days to no avail. The only thing I seem to be able to do is turn ModSecurity off for this vhost. This is fine by me while I'm developing the CMS, but in production this isn't really something I want to do. Does anyone have any ideas on what is causing this issue and how to sort it? The logs seem to point at some kind rules to do with regular expression limits, but since changing my post receiving script to just print out the word test I'm not doing anything with them (Though I have tried upping the limits through <code>SecPcreMatchLimit</code> and <code>SecPcreMatchLimitRecursion</code>). It seems rather that there's something wrong with the amount of data I am sending through.</p>