USN-3523-1: Linux kernel vulnerabilities

Ubuntu Security Notice USN-3523-1

9th January, 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 version:

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

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-2017-16995, CVE-2017-17862, CVE-2017-17863, CVE-2017-17864, CVE-2017-5754