The handle_dr function in arch/x86/kvm/vmx.c in the KVM subsystem in the Linux kernel before 2.6.31.1 does not properly verify the Current Privilege Level (CPL) before accessing a debug register, which allows guest OS users to cause a denial of service (trap) on the host OS via a crafted application.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A9892
https://bugzilla.redhat.com/show_bug.cgi?id=531660
http://www.ubuntu.com/usn/usn-864-1
http://www.securityfocus.com/bid/37221
http://www.redhat.com/support/errata/RHSA-2010-0126.html
http://www.mandriva.com/security/advisories?name=MDVSA-2010:198
http://www.kernel.org/pub/linux/kernel/v2.6/testing/ChangeLog-2.6.32-rc1
http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.31.1
http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.30.9
http://marc.info/?l=oss-security&m=125680666827148&w=2