[USN-3056-1] Linux kernel (Raspberry Pi 2) vulnerabilities

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==========================================================================
Ubuntu Security Notice USN-3056-1
August 10, 2016

linux-raspi2 vulnerabilities
==========================================================================

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

- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in the kernel.

Software Description:
- linux-raspi2: Linux kernel for Raspberry Pi 2

Details:

Ben Hawkes discovered an integer overflow in the Linux netfilter
implementation. On systems running 32 bit kernels, a local unprivileged
attacker could use this to cause a denial of service (system crash) or
possibly execute arbitrary code with administrative privileges.
(CVE-2016-3135)

It was discovered that the keyring implementation in the Linux kernel did
not ensure a data structure was initialized before referencing it after an
error condition occurred. A local attacker could use this to cause a denial
of service (system crash). (CVE-2016-4470)

Sasha Levin discovered that a use-after-free existed in the percpu
allocator in the Linux kernel. A local attacker could use this to cause a
denial of service (system crash) or possibly execute arbitrary code with
administrative privileges. (CVE-2016-4794)

Kangjie Lu discovered an information leak in the netlink implementation of
the Linux kernel. A local attacker could use this to obtain sensitive
information from kernel memory. (CVE-2016-5243)

Update instructions:

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

Ubuntu 16.04 LTS:
linux-image-4.4.0-1019-raspi2 4.4.0-1019.25

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:
http://www.ubuntu.com/usn/usn-3056-1
CVE-2016-3135, CVE-2016-4470, CVE-2016-4794, CVE-2016-5243

Package Information:
https://launchpad.net/ubuntu/+source/linux-raspi2/4.4.0-1019.25