Buffer overflow in the complete_emulated_mmio function in arch/x86/kvm/x86.c in the Linux kernel before 3.13.6 allows guest OS users to execute arbitrary code on the host OS by leveraging a loop that triggers an invalid memory copy affecting certain cancel_work_item data.
https://github.com/torvalds/linux/commit/a08d3b3b99efd509133946056531cdf8f3a0c09b
https://bugzilla.redhat.com/show_bug.cgi?id=1062368
http://www.openwall.com/lists/oss-security/2014/03/03/1
http://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.13.6