A flaw has been found in the way Linux kernel's KVM subsystem handled vcpu->arch.cr4 X86_CR4_OSXSAVE bit set upon guest enter. On hosts without the XSAVE feature an unprivileged local user could use this flaw to crash the system. Acknowledgements: Red Hat would like to thank Jon Howell for reporting this issue.
Statement: This issue did not affect the version of Linux kernel as shipped with Red Hat Enterprise Linux 5. This issue did affect the version of Linux kernel as shipped with Red Hat Enterprise Linux 6. This issue did not affect the version of Linux kernel as shipped with Red Hat Enterprise MRG 2.
Public now via http://article.gmane.org/gmane.comp.emulators.kvm.devel/100742
Upstream fix: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=6d1068b3a98519247d8ba4ec85cd40ac136dbdf9
kernel-3.6.7-4.fc17 has been pushed to the Fedora 17 stable repository. If problems still persist, please make note of it in this bug report.
kernel-3.6.7-5.fc18 has been pushed to the Fedora 18 stable repository. If problems still persist, please make note of it in this bug report.
kernel-3.6.7-4.fc16 has been pushed to the Fedora 16 stable repository. If problems still persist, please make note of it in this bug report.
This issue has been addressed in following products: Red Hat Enterprise Linux 6 Via RHSA-2013:0223 https://rhn.redhat.com/errata/RHSA-2013-0223.html
This issue has been addressed in following products: Red Hat Enterprise Linux 6.2 EUS - Server Only Via RHSA-2013:0882 https://rhn.redhat.com/errata/RHSA-2013-0882.html