The linux-2.4.21-mlock.patch in Red Hat Enterprise Linux 3 does not properly maintain the mlock page count when one process unlocks pages that belong to another process, which allows local users to mlock more memory than specified by the rlimit.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A1117
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10672
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=126411
http://www.securityfocus.com/bid/13769
http://www.redhat.com/support/errata/RHSA-2005-472.html