[USN-3741-1] Linux kernel vulnerabilities

[Steve Beattie]

==========================================================================
Ubuntu Security Notice USN-3741-1
August 14, 2018

linux, linux-aws, linux-kvm, linux-raspi2, linux-snapdragon vulnerabilities
==========================================================================

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

- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux: Linux kernel
- linux-aws: Linux kernel for Amazon Web Services (AWS) systems
- linux-kvm: Linux kernel for cloud environments
- linux-raspi2: Linux kernel for Raspberry Pi 2
- linux-snapdragon: Linux kernel for Snapdragon processors

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)

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 16.04 LTS:
  linux-image-4.4.0-1031-kvm      4.4.0-1031.37
  linux-image-4.4.0-1065-aws      4.4.0-1065.75
  linux-image-4.4.0-1094-raspi2   4.4.0-1094.102
  linux-image-4.4.0-1098-snapdragon  4.4.0-1098.103
  linux-image-4.4.0-133-generic   4.4.0-133.159
  linux-image-4.4.0-133-generic-lpae  4.4.0-133.159
  linux-image-4.4.0-133-lowlatency  4.4.0-133.159
  linux-image-4.4.0-133-powerpc-e500mc  4.4.0-133.159
  linux-image-4.4.0-133-powerpc-smp  4.4.0-133.159
  linux-image-4.4.0-133-powerpc64-emb  4.4.0-133.159
  linux-image-4.4.0-133-powerpc64-smp  4.4.0-133.159
  linux-image-aws                 4.4.0.1065.67
  linux-image-generic             4.4.0.133.139
  linux-image-generic-lpae        4.4.0.133.139
  linux-image-kvm                 4.4.0.1031.30
  linux-image-lowlatency          4.4.0.133.139
  linux-image-powerpc-e500mc      4.4.0.133.139
  linux-image-powerpc-smp         4.4.0.133.139
  linux-image-powerpc64-emb       4.4.0.133.139
  linux-image-powerpc64-smp       4.4.0.133.139
  linux-image-raspi2              4.4.0.1094.94
  linux-image-snapdragon          4.4.0.1098.90

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-3741-1
  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/4.4.0-133.159
  https://launchpad.net/ubuntu/+source/linux-aws/4.4.0-1065.75
  https://launchpad.net/ubuntu/+source/linux-kvm/4.4.0-1031.37
  https://launchpad.net/ubuntu/+source/linux-raspi2/4.4.0-1094.102
  https://launchpad.net/ubuntu/+source/linux-snapdragon/4.4.0-1098.103

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