Ubuntu Security Notice USN-2840-1
17th December, 2015
A security issue affects these releases of Ubuntu and its
- Ubuntu 12.04 LTS
Several security issues were fixed in the kernel.
– Linux kernel
Dmitry Vyukov discovered that the Linux kernel's keyring handler attempted
to garbage collect incompletely instantiated keys. A local unprivileged
attacker could use this to cause a denial of service (system crash).
Jan Beulich discovered that the KVM svm hypervisor implementation in the
Linux kernel did not properly catch Debug exceptions on AMD processors. An
attacker in a guest virtual machine could use this to cause a denial of
service (system crash) in the host OS. (CVE-2015-8104)
The problem can be corrected by updating your system to the following
- Ubuntu 12.04 LTS:
To update your system, please follow these instructions:
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.