A Linux kernel security update has been released for Ubuntu Linux 20.04 LTS.

USN-4389-1: Linux kernel vulnerabilities

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Ubuntu Security Notice USN-4389-1
June 09, 2020

linux, linux-aws, linux-azure, linux-gcp, linux-kvm, linux-oracle
vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux: Linux kernel
- linux-aws: Linux kernel for Amazon Web Services (AWS) systems
- linux-azure: Linux kernel for Microsoft Azure Cloud systems
- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems
- linux-kvm: Linux kernel for cloud environments
- linux-oracle: Linux kernel for Oracle Cloud systems

Details:

It was discovered that the F2FS file system implementation in the Linux
kernel did not properly perform bounds checking on xattrs in some
situations. A local attacker could possibly use this to expose sensitive
information (kernel memory). (CVE-2020-0067)

It was discovered that memory contents previously stored in
microarchitectural special registers after RDRAND, RDSEED, and SGX EGETKEY
read operations on Intel client and Xeon E3 processors may be briefly
exposed to processes on the same or different processor cores. A local
attacker could use this to expose sensitive information. (CVE-2020-0543)

Piotr Krysiuk discovered that race conditions existed in the file system
implementation in the Linux kernel. A local attacker could use this to
cause a denial of service (system crash). (CVE-2020-12114)

It was discovered that the USB susbsystem's scatter-gather implementation
in the Linux kernel did not properly take data references in some
situations, leading to a use-after-free. A physically proximate attacker
could use this to cause a denial of service (system crash) or possibly
execute arbitrary code. (CVE-2020-12464)

Bui Quang Minh discovered that the XDP socket implementation in the Linux
kernel did not properly validate meta-data passed from user space, leading
to an out-of-bounds write vulnerability. A local attacker with the
CAP_NET_ADMIN capability could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2020-12659)

Dmitry Vyukov discovered that the SELinux netlink security hook in the
Linux kernel did not validate messages in some situations. A privileged
attacker could use this to bypass SELinux netlink restrictions.
(CVE-2020-10751)

Update instructions:

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

Ubuntu 20.04 LTS:
linux-image-5.4.0-1015-aws 5.4.0-1015.15
linux-image-5.4.0-1015-gcp 5.4.0-1015.15
linux-image-5.4.0-1015-kvm 5.4.0-1015.15
linux-image-5.4.0-1015-oracle 5.4.0-1015.15
linux-image-5.4.0-1016-azure 5.4.0-1016.16
linux-image-5.4.0-37-generic 5.4.0-37.41
linux-image-5.4.0-37-generic-lpae 5.4.0-37.41
linux-image-5.4.0-37-lowlatency 5.4.0-37.41
linux-image-aws 5.4.0.1015.16
linux-image-azure 5.4.0.1016.16
linux-image-gcp 5.4.0.1015.14
linux-image-generic 5.4.0.37.40
linux-image-generic-hwe-20.04 5.4.0.37.40
linux-image-generic-lpae 5.4.0.37.40
linux-image-generic-lpae-hwe-20.04 5.4.0.37.40
linux-image-gke 5.4.0.1015.14
linux-image-kvm 5.4.0.1015.14
linux-image-lowlatency 5.4.0.37.40
linux-image-lowlatency-hwe-20.04 5.4.0.37.40
linux-image-oem 5.4.0.37.40
linux-image-oem-osp1 5.4.0.37.40
linux-image-oracle 5.4.0.1015.14
linux-image-virtual 5.4.0.37.40
linux-image-virtual-hwe-20.04 5.4.0.37.40

Please note that the mitigation for CVE-2020-0543 requires a processor
microcode update to be applied, either from your system manufacturer
or via the intel-microcode package. The kernel update for this issue
provides the ability to disable the mitigation and to report
vulnerability status.

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/4389-1
CVE-2020-0067, CVE-2020-0543, CVE-2020-10751, CVE-2020-12114,
CVE-2020-12464, CVE-2020-12659,
  https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/SRBDS

Package Information:
  https://launchpad.net/ubuntu/+source/linux/5.4.0-37.41
  https://launchpad.net/ubuntu/+source/linux-aws/5.4.0-1015.15
  https://launchpad.net/ubuntu/+source/linux-azure/5.4.0-1016.16
  https://launchpad.net/ubuntu/+source/linux-gcp/5.4.0-1015.15
  https://launchpad.net/ubuntu/+source/linux-kvm/5.4.0-1015.15
  https://launchpad.net/ubuntu/+source/linux-oracle/5.4.0-1015.15