Published: 13 January 2012
The em_syscall function in arch/x86/kvm/emulate.c in the KVM implementation in the Linux kernel before 3.2.14 does not properly handle the 0f05 (aka syscall) opcode, which allows guest OS users to cause a denial of service (guest OS crash) via a crafted application, as demonstrated by an NASM file.
From the Ubuntu security team
Stephan Bärwolf discovered a flaw in the KVM (kernel-based virtual machine) subsystem of the Linux kernel. A local unprivileged user can crash use this flaw to crash VMs causing a deny of service.
introduced by: e66bb2ccdcf76d032bbb464b35c292bb3ee58f9b current patches appear to be on github but not approved and merged: https://github.com/baerwolf/linux-stephan/commit/a5fad9d83c19a4af9f41b48d78eb1688c8289c7e now upstream (see below)