[USN-4465-1] linux kernel vulnerabilities

Steve Beattie steve.beattie at canonical.com
Wed Aug 19 02:41:17 UTC 2020

Ubuntu Security Notice USN-4465-1
August 19, 2020

linux-hwe, linux-azure-5.3, linux-gke-5.3,  vulnerabilities

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

- Ubuntu 18.04 LTS


Several security issues were fixed in the Linux kernel.

Software Description:
- linux-azure-5.3: Linux kernel for microsoft azure cloud systems
- linux-gke-5.3: Linux kernel for Google Container Engine (GKE) systems
- linux-hwe: Linux hardware enablement (HWE) kernel


It was discovered that the XFS file system implementation in the Linux
kernel did not properly validate meta data in some circumstances. An
attacker could use this to construct a malicious XFS image that, when
mounted, could cause a denial of service. (CVE-2020-12655)

It was discovered that the bcache subsystem in the Linux kernel did not
properly release a lock in some error conditions. A local attacker could
possibly use this to cause a denial of service. (CVE-2020-12771)

Kyungtae Kim discovered that the USB testing driver in the Linux kernel did
not properly deallocate memory on disconnect events. A physically proximate
attacker could use this to cause a denial of service (memory exhaustion).

Update instructions:

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

Ubuntu 18.04 LTS:
  linux-image-5.3.0-1033-gke      5.3.0-1033.35
  linux-image-5.3.0-1035-azure    5.3.0-1035.36
  linux-image-5.3.0-65-generic    5.3.0-65.59
  linux-image-5.3.0-65-lowlatency  5.3.0-65.59

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.

  CVE-2020-12655, CVE-2020-12771, CVE-2020-15393

Package Information:

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