1. Ubuntu Security Notices
  2. USN-5073-1

USN-5073-1: Linux kernel vulnerabilities

Publication date

9 September 2021

Overview

Several security issues were fixed in the Linux kernel.

Releases

Packages

Details

Maxim Levitsky and Paolo Bonzini discovered that the KVM hypervisor
implementation for AMD processors in the Linux kernel allowed a guest VM to
disable restrictions on VMLOAD/VMSAVE in a nested guest. An attacker in a
guest VM could use this to read or write portions of the host's physical
memory. (CVE-2021-3656)

Maxim Levitsky discovered that the KVM hypervisor implementation for AMD
processors in the Linux kernel did not properly prevent a guest VM from
enabling AVIC in nested guest VMs. An attacker in a guest VM could use this
to write to portions of the host's physical memory. (CVE-2021-3653)

Norbert Slusarek discovered that the CAN broadcast manger (bcm) protocol
implementation in the Linux kernel did not properly initialize memory in
some situations. A local attacker could use this to expose sensitive
information (kernel memory). (

Maxim Levitsky and Paolo Bonzini discovered that the KVM hypervisor
implementation for AMD processors in the Linux kernel allowed a guest VM to
disable restrictions on VMLOAD/VMSAVE in a nested guest. An attacker in a
guest VM could use this to read or write portions of the host's physical
memory. (CVE-2021-3656)

Maxim Levitsky discovered that the KVM hypervisor implementation for AMD
processors in the Linux kernel did not properly prevent a guest VM from
enabling AVIC in nested guest VMs. An attacker in a guest VM could use this
to write to portions of the host's physical memory. (CVE-2021-3653)

Norbert Slusarek discovered that the CAN broadcast manger (bcm) protocol
implementation in the Linux kernel did not properly initialize memory in
some situations. A local attacker could use this to expose sensitive
information (kernel memory). (CVE-2021-34693)

Murray McAllister discovered that the joystick device interface in the
Linux kernel did not properly validate data passed via an ioctl(). A local
attacker could use this to cause a denial of service (system crash) or
possibly execute arbitrary code on systems with a joystick device
registered. (CVE-2021-3612)

It was discovered that the Virtio console implementation in the Linux
kernel did not properly validate input lengths in some situations. A local
attacker could possibly use this to cause a denial of service (system
crash). (CVE-2021-38160)

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-4.15.0-1027-dell300x –  4.15.0-1027.32
linux-image-4.15.0-1080-oracle –  4.15.0-1080.88
linux-image-4.15.0-1099-kvm –  4.15.0-1099.101
linux-image-4.15.0-1111-aws –  4.15.0-1111.118
linux-image-4.15.0-1112-snapdragon –  4.15.0-1112.121
linux-image-4.15.0-1123-azure –  4.15.0-1123.136
linux-image-4.15.0-156-generic –  4.15.0-156.163
linux-image-4.15.0-156-generic-lpae –  4.15.0-156.163
linux-image-4.15.0-156-lowlatency –  4.15.0-156.163
linux-image-aws-lts-18.04 –  4.15.0.1111.114
linux-image-azure-lts-18.04 –  4.15.0.1123.96
linux-image-dell300x –  4.15.0.1027.29
linux-image-generic –  4.15.0.156.145
linux-image-generic-lpae –  4.15.0.156.145
linux-image-kvm –  4.15.0.1099.95
linux-image-lowlatency –  4.15.0.156.145
linux-image-oracle-lts-18.04 –  4.15.0.1080.90
linux-image-snapdragon –  4.15.0.1112.115
linux-image-virtual –  4.15.0.156.145
16.04 xenial linux-image-4.15.0-1080-oracle –  4.15.0-1080.88~16.04.1  
linux-image-4.15.0-1111-aws –  4.15.0-1111.118~16.04.1  
linux-image-4.15.0-1123-azure –  4.15.0-1123.136~16.04.1  
linux-image-4.15.0-156-generic –  4.15.0-156.163~16.04.1  
linux-image-4.15.0-156-lowlatency –  4.15.0-156.163~16.04.1  
linux-image-aws-hwe –  4.15.0.1111.102  
linux-image-azure –  4.15.0.1123.114  
linux-image-generic-hwe-16.04 –  4.15.0.156.149  
linux-image-lowlatency-hwe-16.04 –  4.15.0.156.149  
linux-image-oem –  4.15.0.156.149  
linux-image-oracle –  4.15.0.1080.68  
linux-image-virtual-hwe-16.04 –  4.15.0.156.149  
14.04 trusty linux-image-4.15.0-1123-azure –  4.15.0-1123.136~14.04.1  
linux-image-azure –  4.15.0.1123.96  

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References

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