1. Ubuntu Security Notices
  2. USN-4318-1

USN-4318-1: Linux kernel vulnerabilities

Publication date

6 April 2020

Overview

Several security issues were fixed in the Linux kernel.

Releases

Packages

  • 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)

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)

Update instructions

After a standard system update you need to reboot your computer to make all the necessary changes.

Learn more about how to get the fixes.

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.

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

Ubuntu Release Package Version
18.04 bionic 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-virtual –  4.15.0.96.87
16.04 xenial 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

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References

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