==========================================================================
Ubuntu Security Notice USN-3752-2
August 24, 2018

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

Details:

USN-3752-1 fixed vulnerabilities in the Linux kernel for Ubuntu 18.04
LTS. This update provides the corresponding updates for the Linux
Hardware Enablement (HWE) kernel from Ubuntu 18.04 LTS for Ubuntu
16.04 LTS.

It was discovered that, when attempting to handle an out-of-memory
situation, a null pointer dereference could be triggered in the Linux
kernel in some circumstances. A local attacker could use this to cause a
denial of service (system crash). (CVE-2018-1000200)

Wen Xu discovered that the XFS filesystem implementation in the Linux
kernel did not properly validate meta-data information. An attacker could
use this to construct a malicious xfs image that, when mounted, could cause
a denial of service (system crash). (CVE-2018-10323)

Wen Xu discovered that the XFS filesystem implementation in the Linux
kernel did not properly validate xattr information. An attacker could use
this to construct a malicious xfs image that, when mounted, could cause a
denial of service (system crash) or possibly execute arbitrary code.
(CVE-2018-10840)

Wen Xu discovered that the ext4 filesystem implementation in the Linux
kernel did not properly keep meta-data information consistent in some
situations. An attacker could use this to construct a malicious ext4 image
that, when mounted, could cause a denial of service (system crash).
(CVE-2018-10881)

Wen Xu discovered that the ext4 filesystem implementation in the Linux
kernel did not properly handle corrupted meta data in some situations. An
attacker could use this to specially craft an ext4 filesystem that caused a
denial of service (system crash) when mounted. (CVE-2018-1093)

Jann Horn discovered that the Linux kernel's implementation of random seed
data reported that it was in a ready state before it had gathered
sufficient entropy. An attacker could use this to expose sensitive
information. (CVE-2018-1108)

It was discovered that the procfs filesystem did not properly handle
processes mapping some memory elements onto files. A local attacker could
use this to block utilities that examine the procfs filesystem to report
operating system state, such as ps(1). (CVE-2018-1120)

Jann Horn discovered that the ext4 filesystem implementation in the Linux
kernel did not properly keep xattr information consistent in some
situations. An attacker could use this to construct a malicious ext4 image
that, when mounted, could cause a denial of service (system crash) or
possibly execute arbitrary code. (CVE-2018-11412)

Piotr Gabriel Kosinski and Daniel Shapira discovered a stack-based buffer
overflow in the CDROM driver implementation of the Linux kernel. A local
attacker could use this to cause a denial of service (system crash) or
possibly execute arbitrary code. (CVE-2018-11506)

Shankara Pailoor discovered that a race condition existed in the socket
handling code in the Linux kernel. A local attacker could use this to cause
a denial of service (system crash). (CVE-2018-12232)

Shankara Pailoor discovered that the JFS filesystem implementation in the
Linux kernel contained a buffer overflow when handling extended attributes.
A local attacker could use this to cause a denial of service (system crash)
or possibly execute arbitrary code. (CVE-2018-12233)

Felix Wilhelm discovered that the KVM implementation in the Linux kernel
did not properly perform permission checks in some situations when nested
virtualization is used. An attacker in a guest VM could possibly use this
to escape into an outer VM or the host OS. (CVE-2018-12904)

Wen Xu discovered that the XFS filesystem implementation in the Linux
kernel did not properly handle an error condition with a corrupted xfs
image. An attacker could use this to construct a malicious xfs image that,
when mounted, could cause a denial of service (system crash).
(CVE-2018-13094)

It was discovered that the Linux kernel did not properly handle setgid file
creation when performed by a non-member of the group. A local attacker
could use this to gain elevated privileges. (CVE-2018-13405)

Silvio Cesare discovered that the generic VESA frame buffer driver in the
Linux kernel contained an integer overflow. A local attacker could use this
to cause a denial of service (system crash) or possibly execute arbitrary
code. (CVE-2018-13406)

Jakub Jirasek discovered that multiple use-after-free errors existed in the
USB/IP implementation in the Linux kernel. A local attacker could use this
to cause a denial of service (system crash) or possibly execute arbitrary
code. (CVE-2018-5814)

It was discovered that a race condition existed in the ARM Advanced
Microcontroller Bus Architecture (AMBA) driver in the Linux kernel that
could result in a double free. A local attacker could use this to cause a
denial of service (system crash) or possibly execute arbitrary code.
(CVE-2018-9415)

It was discovered that an information leak existed in the generic SCSI
driver in the Linux kernel. A local attacker could use this to expose
sensitive information (kernel memory). (CVE-2018-1000204)

Update instructions:

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

Ubuntu 16.04 LTS:
  linux-image-4.15.0-33-generic   4.15.0-33.36~16.04.1
  linux-image-4.15.0-33-generic-lpae  4.15.0-33.36~16.04.1
  linux-image-4.15.0-33-lowlatency  4.15.0-33.36~16.04.1
  linux-image-generic-hwe-16.04   4.15.0.33.55
  linux-image-generic-lpae-hwe-16.04  4.15.0.33.55
  linux-image-lowlatency-hwe-16.04  4.15.0.33.55

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-3752-2
  https://usn.ubuntu.com/usn/usn-3752-1
  CVE-2018-1000200, CVE-2018-1000204, CVE-2018-10323, CVE-2018-10840,
  CVE-2018-10881, CVE-2018-1093, CVE-2018-1108, CVE-2018-1120,
  CVE-2018-11412, CVE-2018-11506, CVE-2018-12232, CVE-2018-12233,
  CVE-2018-12904, CVE-2018-13094, CVE-2018-13405, CVE-2018-13406,
  CVE-2018-5814, CVE-2018-9415

Package Information:
  https://launchpad.net/ubuntu/+source/linux-hwe/4.15.0-33.36~16.04.1