[USN-3872-1] Linux kernel (HWE) vulnerabilities

[Steve Beattie]

==========================================================================
Ubuntu Security Notice USN-3872-1
January 29, 2019

linux-hwe vulnerabilities
==========================================================================

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

- Ubuntu 18.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux-hwe: Linux hardware enablement (HWE) kernel

Details:

It was discovered that a race condition existed in the vsock address family
implementation of the Linux kernel that could lead to a use-after-free
condition. A local attacker in a guest virtual machine could use this to
expose sensitive information (host machine kernel memory). (CVE-2018-14625)

Cfir Cohen discovered that a use-after-free vulnerability existed in the
KVM implementation of the Linux kernel, when handling interrupts in
environments where nested virtualization is in use (nested KVM
virtualization is not enabled by default in Ubuntu kernels). A local
attacker in a guest VM could possibly use this to gain administrative
privileges in a host machine. (CVE-2018-16882)

Wei Wu discovered that the KVM implementation in the Linux kernel did not
properly ensure that ioapics were initialized. A local attacker could use
this to cause a denial of service (system crash). (CVE-2018-19407)

It was discovered that the crypto subsystem of the Linux kernel leaked
uninitialized memory to user space in some situations. A local attacker
could use this to expose sensitive information (kernel memory).
(CVE-2018-19854)

Update instructions:

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

Ubuntu 18.04 LTS:
  linux-image-4.18.0-14-generic   4.18.0-14.15~18.04.1
  linux-image-4.18.0-14-generic-lpae  4.18.0-14.15~18.04.1
  linux-image-4.18.0-14-lowlatency  4.18.0-14.15~18.04.1
  linux-image-4.18.0-14-snapdragon  4.18.0-14.15~18.04.1
  linux-image-generic-hwe-18.04   4.18.0.14.64
  linux-image-generic-lpae-hwe-18.04  4.18.0.14.64
  linux-image-lowlatency-hwe-18.04  4.18.0.14.64
  linux-image-snapdragon-hwe-18.04  4.18.0.14.64

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-3872-1
  CVE-2018-14625, CVE-2018-16882, CVE-2018-19407, CVE-2018-19854

Package Information:
  https://launchpad.net/ubuntu/+source/linux-hwe/4.18.0-14.15~18.04.1

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