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Ubuntu Security Notice USN-3742-1
August 14, 2018

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

- Ubuntu 14.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux: Linux kernel

Details:

It was discovered that memory present in the L1 data cache of an Intel CPU
core may be exposed to a malicious process that is executing on the CPU
core. This vulnerability is also known as L1 Terminal Fault (L1TF). A local
attacker in a guest virtual machine could use this to expose sensitive
information (memory from other guests or the host OS). (CVE-2018-3646)

It was discovered that memory present in the L1 data cache of an Intel CPU
core may be exposed to a malicious process that is executing on the CPU
core. This vulnerability is also known as L1 Terminal Fault (L1TF). A local
attacker could use this to expose sensitive information (memory from the
kernel or other processes). (CVE-2018-3620)

Andrey Konovalov discovered an out-of-bounds read in the POSIX
timers subsystem in the Linux kernel. A local attacker could use
this to cause a denial of service (system crash) or expose sensitive
information. (CVE-2017-18344)

Juha-Matti Tilli discovered that the TCP implementation in the Linux kernel
performed algorithmically expensive operations in some situations when
handling incoming packets. A remote attacker could use this to cause a
denial of service. (CVE-2018-5390)

Juha-Matti Tilli discovered that the IP implementation in the Linux kernel
performed algorithmically expensive operations in some situations when
handling incoming packet fragments. A remote attacker could use this to
cause a denial of service. (CVE-2018-5391)

Update instructions:

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

Ubuntu 14.04 LTS:
  linux-image-3.13.0-155-generic  3.13.0-155.205
  linux-image-3.13.0-155-generic-lpae  3.13.0-155.205
  linux-image-3.13.0-155-lowlatency  3.13.0-155.205
  linux-image-3.13.0-155-powerpc-e500  3.13.0-155.205
  linux-image-3.13.0-155-powerpc-e500mc  3.13.0-155.205
  linux-image-3.13.0-155-powerpc-smp  3.13.0-155.205
  linux-image-3.13.0-155-powerpc64-emb  3.13.0-155.205
  linux-image-3.13.0-155-powerpc64-smp  3.13.0-155.205
  linux-image-generic             3.13.0.155.165
  linux-image-generic-lpae        3.13.0.155.165
  linux-image-lowlatency          3.13.0.155.165
  linux-image-powerpc-e500        3.13.0.155.165
  linux-image-powerpc-e500mc      3.13.0.155.165
  linux-image-powerpc-smp         3.13.0.155.165
  linux-image-powerpc64-emb       3.13.0.155.165
  linux-image-powerpc64-smp       3.13.0.155.165

Please note that the recommended mitigation for CVE-2018-3646 involves
updating processor microcode in addition to updating the kernel;
however, the kernel includes a fallback for processors that have not
received microcode updates.

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://usn.ubuntu.com/usn/usn-3742-1
  CVE-2017-18344, CVE-2018-3620, CVE-2018-3646, CVE-2018-5390,
  CVE-2018-5391,
  https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/L1TF

Package Information:
  https://launchpad.net/ubuntu/+source/linux/3.13.0-155.205