USN-3169-2: Linux kernel (Xenial HWE) vulnerabilities

Ubuntu Security Notice USN-3169-2

11th January, 2017

linux-lts-xenial vulnerabilities

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

  • Ubuntu 14.04 LTS

Summary

Several security issues were fixed in the kernel.

Software description

  • linux-lts-xenial - Linux hardware enablement kernel from Xenial for Trusty

Details

USN-3169-1 fixed vulnerabilities in the Linux kernel for Ubuntu 16.04
LTS. This update provides the corresponding updates for the Linux
Hardware Enablement (HWE) kernel from Ubuntu 16.04 LTS for Ubuntu
14.04 LTS.

Dmitry Vyukov discovered that the KVM implementation in the Linux kernel
did not properly initialize the Code Segment (CS) in certain error cases. A
local attacker could use this to expose sensitive information (kernel
memory). (CVE-2016-9756)

Andrey Konovalov discovered that signed integer overflows existed in the
setsockopt() system call when handling the SO_SNDBUFFORCE and
SO_RCVBUFFORCE options. A local attacker with the CAP_NET_ADMIN capability
could use this to cause a denial of service (system crash or memory
corruption). (CVE-2016-9793)

Baozeng Ding discovered a race condition that could lead to a use-after-
free in the Advanced Linux Sound Architecture (ALSA) subsystem of the Linux
kernel. A local attacker could use this to cause a denial of service
(system crash). (CVE-2016-9794)

Update instructions

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

Ubuntu 14.04 LTS:
linux-image-powerpc-smp-lts-xenial 4.4.0.59.46
linux-image-generic-lpae-lts-xenial 4.4.0.59.46
linux-image-4.4.0-59-powerpc64-smp 4.4.0-59.80~14.04.1
linux-image-4.4.0-59-lowlatency 4.4.0-59.80~14.04.1
linux-image-4.4.0-59-generic 4.4.0-59.80~14.04.1
linux-image-4.4.0-59-powerpc64-emb 4.4.0-59.80~14.04.1
linux-image-4.4.0-59-powerpc-smp 4.4.0-59.80~14.04.1
linux-image-lowlatency-lts-xenial 4.4.0.59.46
linux-image-generic-lts-xenial 4.4.0.59.46
linux-image-4.4.0-59-generic-lpae 4.4.0-59.80~14.04.1
linux-image-4.4.0-59-powerpc-e500mc 4.4.0-59.80~14.04.1
linux-image-powerpc64-smp-lts-xenial 4.4.0.59.46
linux-image-powerpc64-emb-lts-xenial 4.4.0.59.46
linux-image-powerpc-e500mc-lts-xenial 4.4.0.59.46

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.
Unless you manually uninstalled the standard kernel metapackages
(e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual,
linux-powerpc), a standard system upgrade will automatically perform
this as well.

References

CVE-2016-9756, CVE-2016-9793, CVE-2016-9794