On some hardware, during live migration of 64-bit PV guests, some parts of the guest's shadow pagetables are mistakenly filled in with hypervisor mappings. This causes Xen to crash when those mappings are later cleared. Before the crash, a malicious guest could use hypercalls to cause Xen to read and write the parts of memory pointed to by the stray mappings. A malicious 64-bit PV guest, on a vulnerable host system, that can arrange for itself to be live migrated could use this flaw to read or write memory at the high physical addresses on the host. Acknowledgements: Red Hat would like to thank the Xen project for reporting this issue.
Statement: This issue does not affect the versions of the kernel-xen package as shipped with Red Hat Enterprise Linux 5. This issue does not affect the versions of the Linux kernel package as shipped with Red Hat Enterprise Linux 6 and Red Hat Enterprise MRG as it does not have support for Xen hypervisor.
This is now public: http://www.openwall.com/lists/oss-security/2013/09/30/2
Created xen tracking bugs for this issue: Affects: fedora-all [bug 1013748]