RHSA-2021:3802 - Security Advisory

Topic

An update for kernel-rt is now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

The kernel-rt packages provide the Real Time Linux Kernel, which enables fine-tuning for systems with extremely high determinism requirements.

Security Fix(es):

• kernel: Improper handling of VM_IO|VM_PFNMAP vmas in KVM can bypass RO checks (CVE-2021-22543)
• kernel: SVM nested virtualization issue in KVM (AVIC support) (CVE-2021-3653)
• kernel: SVM nested virtualization issue in KVM (VMLOAD/VMSAVE) (CVE-2021-3656)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Bug Fix(es):

• Indefinite waiting for RCU callback while removing cgroup (BZ#1967844)
• kernel-rt: update to the latest RHEL7.9.z9 source tree (BZ#2002994)

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.

Affected Products

• Red Hat Enterprise Linux for Real Time 7 x86_64
• Red Hat Enterprise Linux for Real Time for NFV 7 x86_64

Fixes

• BZ - 1965461 - CVE-2021-22543 kernel: Improper handling of VM_IO|VM_PFNMAP vmas in KVM can bypass RO checks
• BZ - 1967844 - Indefinite waiting for RCU callback while removing cgroup
• BZ - 1983686 - CVE-2021-3653 kernel: SVM nested virtualization issue in KVM (AVIC support)
• BZ - 1983988 - CVE-2021-3656 kernel: SVM nested virtualization issue in KVM (VMLOAD/VMSAVE)

CVEs

• CVE-2021-3653
• CVE-2021-3656
• CVE-2021-22543

References

• https://access.redhat.com/security/updates/classification/#important