The kvm_set_msr_common function in arch/x86/kvm/x86.c in the Linux kernel through 3.8.4 does not ensure a required time_page alignment during an MSR_KVM_SYSTEM_TIME operation, which allows guest OS users to cause a denial of service (buffer overflow and host OS memory corruption) or possibly have unspecified other impact via a crafted application.
https://github.com/torvalds/linux/commit/c300aa64ddf57d9c5d9c898a64b36877345dd4a9
https://bugzilla.redhat.com/show_bug.cgi?id=917012
http://www.ubuntu.com/usn/USN-1813-1
http://www.ubuntu.com/usn/USN-1812-1
http://www.ubuntu.com/usn/USN-1809-1
http://www.ubuntu.com/usn/USN-1808-1
http://www.ubuntu.com/usn/USN-1805-1
http://www.securityfocus.com/bid/58607
http://www.openwall.com/lists/oss-security/2013/03/20/9
http://www.mandriva.com/security/advisories?name=MDVSA-2013:176
http://rhn.redhat.com/errata/RHSA-2013-1026.html
http://rhn.redhat.com/errata/RHSA-2013-0928.html
http://rhn.redhat.com/errata/RHSA-2013-0746.html
http://rhn.redhat.com/errata/RHSA-2013-0744.html
http://rhn.redhat.com/errata/RHSA-2013-0727.html
http://lists.opensuse.org/opensuse-security-announce/2013-07/msg00018.html
http://lists.opensuse.org/opensuse-security-announce/2013-06/msg00005.html
http://lists.opensuse.org/opensuse-security-announce/2013-05/msg00018.html