The Linux kernel before 3.3.1, when KVM is used, allows guest OS users to cause a denial of service (host OS crash) by leveraging administrative access to the guest OS, related to the pmd_none_or_clear_bad function and page faults for huge pages.
https://github.com/torvalds/linux/commit/4a1d704194a441bf83c636004a479e01360ec850
https://bugzilla.redhat.com/show_bug.cgi?id=803793
http://www.securitytracker.com/id?1027084
http://www.openwall.com/lists/oss-security/2012/03/15/7
http://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.3.1
http://secunia.com/advisories/48898
http://secunia.com/advisories/48404
http://rhn.redhat.com/errata/RHSA-2012-0743.html
http://marc.info/?l=bugtraq&m=139447903326211&w=2
http://lists.opensuse.org/opensuse-security-announce/2012-04/msg00021.html
http://lists.fedoraproject.org/pipermail/package-announce/2012-March/075781.html