USN-2840-1: Linux kernel vulnerabilities

Ubuntu Security Notice USN-2840-1

17th December, 2015

linux vulnerabilities

A security issue affects these releases of Ubuntu and its
derivatives:

  • Ubuntu 12.04 LTS

Summary

Several security issues were fixed in the kernel.

Software description

  • linux
    – Linux kernel

Details

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).
(CVE-2015-7872)

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)

Update instructions

The problem can be corrected by updating your system to the following
package version:

Ubuntu 12.04 LTS:
linux-image-3.2.0-96-generic

3.2.0-96.136
linux-image-3.2.0-96-powerpc-smp

3.2.0-96.136
linux-image-3.2.0-96-virtual

3.2.0-96.136
linux-image-3.2.0-96-highbank

3.2.0-96.136
linux-image-3.2.0-96-omap

3.2.0-96.136
linux-image-3.2.0-96-generic-pae

3.2.0-96.136
linux-image-3.2.0-96-powerpc64-smp

3.2.0-96.136

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.

References

CVE-2015-7872,

CVE-2015-8104

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