QID 198491

Date Published: 2021-09-15

QID 198491: Ubuntu Security Notification for Linux kernel Vulnerabilities (USN-5070-1)

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.
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.
The linux kernel did not properly enforce certain types of entries in the secure boot forbidden signature database (aka dbx) protection mechanism.
The kvm hypervisor implementation in the linux kernel did not properly perform reference counting in some situations, leading to a use-after-free vulnerability.
The can broadcast manger (bcm) protocol implementation in the linux kernel did not properly initialize memory in some situations.
The joystick device interface in the linux kernel did not properly validate data passed via an ioctl().the kvm hypervisor implementation in the linux kernel did not properly compute the access permissions for shadow pages in some situations.
The perf subsystem in the linux kernel for the powerpc architecture contained a null pointer dereference in some situations.
The mac80211 subsystem in the linux kernel contained a null pointer dereference in some situations.
The xilinx ll temac device driver in the linux kernel did not properly calculate the number of buffers to be used in certain situations.

Note: The preceding description block is extracted directly from the security advisory. Using automation, we have attempted to clean and format it as much as possible without introducing additional issues.

an attacker in a guest vm could use this to read or write portions of the host's physical memory. (
Cve-2021-3656).
An attacker in a guest vm could use this to write to portions of the host's physical memory. (
Cve-2021-3653).
An attacker could use this to bypass uefi secure boot restrictions. (
Cve-2020-26541).
An attacker who could start and control a vm could possibly use this to expose sensitive information or execute arbitrary code. (
Cve-2021-22543).
A local attacker could use this to expose sensitive information (kernel memory) (cve-2021-34693).
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).
A local attacker could use this to cause a denial of service. (
Cve-2021-38198).
An attacker could use this to cause a denial of service (system crash) (cve-2021-38200).
A physically proximate attacker could possibly use this to cause a denial of service (system crash) (cve-2021-38206).
A remote attacker could use this to cause a denial of service (system crash) (cve-2021-38207).

  • CVSS V3 rated as High - 7.8 severity.
  • CVSS V2 rated as High - 7.2 severity.
  • Solution
    Refer to Ubuntu advisory: USN-5070-1 for affected packages and patching details, or update with your package manager.
    Vendor References
    Software Advisories
    Advisory ID Software Component Link
    USN-5070-1 Ubuntu Linux URL Logo ubuntu.com/security/notices/USN-5070-1