A Linux kernel security update has been released for Ubuntu Linux 14.04 ESM and 16.04 LTS to address several security issues in linux-kvm, linux-raspi2, linux-snapdragon, and linux-aws kernels.

USN-4709-1: Linux kernel vulnerabilities

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Ubuntu Security Notice USN-4709-1
January 28, 2021

linux-aws, linux-kvm, linux-raspi2, linux-snapdragon vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 16.04 LTS
- Ubuntu 14.04 ESM

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux-kvm: Linux kernel for cloud environments
- linux-raspi2: Linux kernel for Raspberry Pi (V8) systems
- linux-snapdragon: Linux kernel for Qualcomm Snapdragon processors
- linux-aws: Linux kernel for Amazon Web Services (AWS) systems

Details:

It was discovered that the LIO SCSI target implementation in the Linux
kernel performed insufficient identifier checking in certain XCOPY
requests. An attacker with access to at least one LUN in a multiple
backstore environment could use this to expose sensitive information or
modify data. (CVE-2020-28374)

Wen Xu discovered that the XFS filesystem implementation in the Linux
kernel did not properly track inode validations. An attacker could use this
to construct a malicious XFS image that, when mounted, could cause a denial
of service (system crash). (CVE-2018-13093)

It was discovered that the btrfs file system implementation in the Linux
kernel did not properly validate file system metadata in some situations.
An attacker could use this to construct a malicious btrfs image that, when
mounted, could cause a denial of service (system crash). (CVE-2019-19813,
CVE-2019-19816)

Bodong Zhao discovered a use-after-free in the Sun keyboard driver
implementation in the Linux kernel. A local attacker could use this to
cause a denial of service or possibly execute arbitrary code.
(CVE-2020-25669)

Update instructions:

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

Ubuntu 16.04 LTS:
linux-image-4.4.0-1087-kvm 4.4.0-1087.96
linux-image-4.4.0-1145-raspi2 4.4.0-1145.155
linux-image-4.4.0-1149-snapdragon 4.4.0-1149.159
linux-image-kvm 4.4.0.1087.85
linux-image-raspi2 4.4.0.1145.145
linux-image-snapdragon 4.4.0.1149.141

Ubuntu 14.04 ESM:
linux-image-4.4.0-1085-aws 4.4.0-1085.89
linux-image-aws 4.4.0.1085.82

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/4709-1
CVE-2018-13093, CVE-2019-19813, CVE-2019-19816, CVE-2020-25669,
CVE-2020-28374

Package Information:
  https://launchpad.net/ubuntu/+source/linux-kvm/4.4.0-1087.96
  https://launchpad.net/ubuntu/+source/linux-raspi2/4.4.0-1145.155
  https://launchpad.net/ubuntu/+source/linux-snapdragon/4.4.0-1149.159