The system could be made to crash under certain conditions.
Ben Serebrin discovered that the KVM hypervisor implementation in the Linux kernel did not properly catch Alignment Check exceptions. An attacker in a guest virtual machine could use this to cause a denial of service (system crash) in the host OS.
10 November 2015
A security issue affects these releases of Ubuntu and its derivatives:
The system could be made to crash under certain conditions.
Ben Serebrin discovered that the KVM hypervisor implementation in the Linux kernel did not properly catch Alignment Check exceptions. An attacker in a guest virtual machine could use this to cause a denial of service (system crash) in the host OS.
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
After a standard system update you need to reboot your computer to make all the necessary changes.
ATTENTION: Due to an unavoidable ABI change the kernel updates have been given a new version number, which requires you to recompile and reinstall all third party kernel modules you might have installed. If you use linux-restricted-modules, you have to update that package as well to get modules which work with the new kernel version. Unless you manually uninstalled the standard kernel metapackages (e.g. linux-generic, linux-server, linux-powerpc), a standard system upgrade will automatically perform this as well.
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