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Ubuntu 18.04 LTS - Security Advisory USN-4318-1: Severe Kernel Threats

ubuntu
Calendar Grey April 6, 2020
Dist Ubuntu Esm H88
Ubuntu security notice USN-4319-1 highlights severe kernel vulnerabilities; updates essential for protection.
Several security issues were fixed in the Linux kernel.

Summary

Several security issues were fixed in the Linux kernel.

Software Description:

- linux: Linux kernel

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

Details:

Al Viro discovered that the vfs layer in the Linux kernel contained a use-

after-free vulnerability. A local attacker could use this to cause a denial

of service (system crash) or possibly expose sensitive information (kernel

memory). (CVE-2020-8428)

Gustavo Romero and Paul Mackerras discovered that the KVM implementation in

the Linux kernel for PowerPC processors did not properly keep guest state

separate from host state. A local attacker in a KVM guest could use this to

cause a denial of service (host system crash). (CVE-2020-8834)

Shijie Luo discovered that the ext4 file system implementation in the Linux

kernel did not properly check for a too-large journal size. An attacker

could use this to construct a malicious ext4 image that, when mounted,

could cause a denial of service (soft lockup). (CVE-2020-8992)

Topics%20covered

Topics Covered

security advisory denial of service Ubuntu kernel KVM use-after-free ext4

Update Instructions

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

Ubuntu 18.04 LTS:
  linux-image-4.15.0-96-generic   4.15.0-96.97
  linux-image-4.15.0-96-generic-lpae  4.15.0-96.97
  linux-image-4.15.0-96-lowlatency  4.15.0-96.97
  linux-image-generic             4.15.0.96.87
  linux-image-generic-lpae        4.15.0.96.87
  linux-image-lowlatency          4.15.0.96.87
  linux-image-powerpc-e500mc      4.15.0.96.87
  linux-image-powerpc-smp         4.15.0.96.87
  linux-image-powerpc64-emb       4.15.0.96.87
  linux-image-powerpc64-smp       4.15.0.96.87
  linux-image-virtual             4.15.0.96.87

Ubuntu 16.04 LTS:
  linux-image-4.15.0-96-generic   4.15.0-96.97~16.04.1
  linux-image-4.15.0-96-generic-lpae  4.15.0-96.97~16.04.1
  linux-image-4.15.0-96-lowlatency  4.15.0-96.97~16.04.1
  linux-image-generic-hwe-16.04   4.15.0.96.104
  linux-image-generic-lpae-hwe-16.04  4.15.0.96.104
  linux-image-lowlatency-hwe-16.04  4.15.0.96.104
  linux-image-oem                 4.15.0.96.104
  linux-image-virtual-hwe-16.04   4.15.0.96.104

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://ubuntu.com/security/notices/USN-4318-1

CVE-2020-8428, CVE-2020-8834, CVE-2020-8992

Severity
critical
Lowest
Low
Medium
High
Critical

April 06, 2020

Topics%20covered

Topics Covered

security advisory denial of service Ubuntu kernel KVM use-after-free ext4

Package Information

https://launchpad.net/ubuntu/+source/linux/4.15.0-96.97
https://launchpad.net/ubuntu/+source/linux-hwe/4.15.0-96.97~16.04.1

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