USN-5072-1: Linux kernel vulnerabilities
8 September 2021
Several security issues were fixed in the Linux kernel.
Releases
Packages
- linux-azure-5.8 - Linux kernel for Microsoft Azure cloud systems
- linux-oem-5.10 - Linux kernel for OEM systems
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)
Update instructions
The problem can be corrected by updating your system to the following package versions:
Ubuntu 20.04
-
linux-image-oem-20.04b
-
5.10.0.1045.47
-
linux-image-5.10.0-1045-oem
-
5.10.0-1045.47
-
linux-image-oem-20.04
-
5.10.0.1045.47
-
linux-image-5.8.0-1041-azure
-
5.8.0-1041.44~20.04.1
-
linux-image-azure
-
5.8.0.1041.44~20.04.13
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.