The ptrace call in the Linux kernel 2.6.8.1 and 2.6.10 for the AMD64 platform allows local users to cause a denial of service (kernel crash) via a "non-canonical" address.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10630
http://www.vupen.com/english/advisories/2005/1878
http://www.securityfocus.com/bid/13904
http://www.securityfocus.com/archive/1/428058/100/0/threaded
http://www.securityfocus.com/archive/1/427980/100/0/threaded
http://www.redhat.com/support/errata/RHSA-2005-663.html
http://www.redhat.com/support/errata/RHSA-2005-514.html
http://www.novell.com/linux/security/advisories/2005_29_kernel.html
http://www.debian.org/security/2005/dsa-922
http://www.debian.org/security/2005/dsa-921
http://secunia.com/advisories/18059
http://secunia.com/advisories/18056
http://secunia.com/advisories/17073