Just an update on this issue.
I’m aware that this is a php error, but since this error only started to appear after 1.3, I’m tempted to say that something was changed in the Piwik code that doesn’t play with php too nicely.
I hadn’t seen any ALERT - canary mismatch on efree() messages for the last 10 days so I thought the problem had solved itself. But last night I started getting heaps of them again. What’s weird is the order of the messages
May 19 01:05:01 boxfish /USR/SBIN/CRON: (root) CMD (/var/www/www_v2/app/webroot/piwik/misc/cron/archive.sh > /dev/null)
May 19 01:09:01 boxfish /USR/SBIN/CRON: (root) CMD ( [ -x /usr/lib/php5/maxlifetime ] && [ -d /var/lib/php5 ] && find /var/lib/php5/ -depth -mindepth 1 -maxdepth 1 -type f -cmin +$(/usr/lib/php5/maxlifetime) -delete)
May 19 01:09:21 boxfish suhosin: ALERT - canary mismatch on efree() - heap overflow detected (attacker ‘184.108.40.206’, file ‘/var/www/www_v2/app/views/layouts/fullscreen_v2.ctp’, line 49)
(no lines omitted, either the archive or the session rake script COULD have something to do with it)
The bad thing for me is that apache croaks after the fifth message. It only delivers empty pages which brings down the entire site. After restarting it, everything is back to normal.
So does anyone have any suggestion on how to fix this? Any help would be highly appreciated.