The pit_ioport_read function in the Programmable Interval Timer (PIT) emulation in i8254.c in KVM 83 does not properly use the pit_state data structure, which allows guest OS users to cause a denial of service (host OS crash or hang) by attempting to read the /dev/port file.
https://rhn.redhat.com/errata/RHSA-2010-0095.html
https://rhn.redhat.com/errata/RHSA-2010-0088.html
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11095
https://bugzilla.redhat.com/show_bug.cgi?id=560887
http://www.vupen.com/english/advisories/2010/0638
http://www.ubuntu.com/usn/USN-914-1
http://www.securityfocus.com/bid/38158
http://www.openwall.com/lists/oss-security/2010/02/02/4
http://www.openwall.com/lists/oss-security/2010/02/02/1
http://www.mail-archive.com/kvm%40vger.kernel.org/msg28002.html
http://www.debian.org/security/2010/dsa-1996