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Ubuntu Security Notice USN-4069-2
August 01, 2019

linux-hwe vulnerabilities
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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:

USN-4069-1 fixed vulnerabilities in the Linux kernel for Ubuntu 19.04.
This update provides the corresponding updates for the Linux Hardware
Enablement (HWE) kernel from Ubuntu 19.04 for Ubuntu 18.04 LTS.

It was discovered that an integer overflow existed in the Linux kernel when
reference counting pages, leading to potential use-after-free issues. A
local attacker could use this to cause a denial of service (system crash)
or possibly execute arbitrary code. (CVE-2019-11487)

Jann Horn discovered that a race condition existed in the Linux kernel when
performing core dumps. A local attacker could use this to cause a denial of
service (system crash) or expose sensitive information. (CVE-2019-11599)

It was discovered that the ext4 file system implementation in the Linux
kernel did not properly zero out memory in some situations. A local
attacker could use this to expose sensitive information (kernel memory).
(CVE-2019-11833)

It was discovered that the Bluetooth Human Interface Device Protocol (HIDP)
implementation in the Linux kernel did not properly verify strings were
NULL terminated in certain situations. A local attacker could use this to
expose sensitive information (kernel memory). (CVE-2019-11884)

Update instructions:

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

Ubuntu 18.04 LTS:
  linux-image-5.0.0-23-generic    5.0.0-23.24~18.04.1
  linux-image-5.0.0-23-generic-lpae  5.0.0-23.24~18.04.1
  linux-image-5.0.0-23-lowlatency  5.0.0-23.24~18.04.1
  linux-image-generic-hwe-18.04   5.0.0.23.80
  linux-image-generic-lpae-hwe-18.04  5.0.0.23.80
  linux-image-lowlatency-hwe-18.04  5.0.0.23.80
  linux-image-snapdragon-hwe-18.04  5.0.0.23.80
  linux-image-virtual-hwe-18.04   5.0.0.23.80

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/4069-2
  https://usn.ubuntu.com/4069-1
  CVE-2019-11487, CVE-2019-11599, CVE-2019-11833, CVE-2019-11884

Package Information:
  https://launchpad.net/ubuntu/+source/linux-hwe/5.0.0-23.24~18.04.1