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Ubuntu Security Notice USN-3523-1
January 09, 2018

linux vulnerabilities
==========================================================================

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

– Ubuntu 17.10

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
– linux: Linux kernel

Details:

Jann Horn discovered that microprocessors utilizing speculative execution
and indirect branch prediction may allow unauthorized memory reads via
sidechannel attacks. This flaw is known as Meltdown. A local attacker could
use this to expose sensitive information, including kernel memory.
(CVE-2017-5754)

Jann Horn discovered that the Berkeley Packet Filter (BPF) implementation
in the Linux kernel did not properly check the relationship between pointer
values and the BPF stack. A local attacker could use this to cause a denial
of service (system crash) or possibly execute arbitrary code.
(CVE-2017-17863)

Jann Horn discovered that the Berkeley Packet Filter (BPF) implementation
in the Linux kernel improperly performed sign extension in some situations.
A local attacker could use this to cause a denial of service (system crash)
or possibly execute arbitrary code. (CVE-2017-16995)

Alexei Starovoitov discovered that the Berkeley Packet Filter (BPF)
implementation in the Linux kernel contained a branch-pruning logic issue
around unreachable code. A local attacker could use this to cause a denial
of service. (CVE-2017-17862)

Jann Horn discovered that the Berkeley Packet Filter (BPF) implementation
in the Linux kernel mishandled pointer data values in some situations. A
local attacker could use this to to expose sensitive information (kernel
memory). (CVE-2017-17864)

Update instructions:

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

Ubuntu 17.10:
linux-image-4.13.0-25-generic 4.13.0-25.29
linux-image-4.13.0-25-lowlatency 4.13.0-25.29
linux-image-generic 4.13.0.25.26
linux-image-lowlatency 4.13.0.25.26

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:
https://www.ubuntu.com/usn/usn-3523-1
CVE-2017-16995, CVE-2017-17862, CVE-2017-17863, CVE-2017-17864,
CVE-2017-5754

Package Information:
https://launchpad.net/ubuntu/+source/linux/4.13.0-25.29

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