Important: kernel-rt security and bug fix update

Topic

An update for kernel-rt is now available for Red Hat Enterprise Linux 8.4 Extended Update Support.

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):

• A use-after-free in cls_route filter implementation may lead to privilege escalation (CVE-2022-2588)
• Information leak in the IPv6 implementation (CVE-2021-45485)
• Information leak in the IPv4 implementation (CVE-2021-45486)
• Incomplete cleanup of multi-core shared buffers (aka SBDR) (CVE-2022-21123)
• Incomplete cleanup of microarchitectural fill buffers (aka SBDS) (CVE-2022-21125)
• Incomplete cleanup in specific special register write operations (aka DRPW) (CVE-2022-21166)

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):

• update RT source tree to the RHEL-8.4.z12 source tree (BZ#2119160)
• using __this_cpu_add() in preemptible [00000000] - caller is __mod_memcg_lruvec_state+0x69/0x1c0 [None8.4.0.z] (BZ#2124454)

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 - Telecommunications Update Service 8.4 x86_64
• Red Hat Enterprise Linux for Real Time for NFV - Telecommunications Update Service 8.4 x86_64

Fixes

• BZ - 2039911 - CVE-2021-45485 kernel: information leak in the IPv6 implementation
• BZ - 2039914 - CVE-2021-45486 kernel: information leak in the IPv4 implementation
• BZ - 2090237 - CVE-2022-21123 hw: cpu: Incomplete cleanup of multi-core shared buffers (aka SBDR)
• BZ - 2090240 - CVE-2022-21125 hw: cpu: Incomplete cleanup of microarchitectural fill buffers (aka SBDS)
• BZ - 2090241 - CVE-2022-21166 hw: cpu: Incomplete cleanup in specific special register write operations (aka DRPW)
• BZ - 2114849 - CVE-2022-2588 kernel: a use-after-free in cls_route filter implementation may lead to privilege escalation

CVEs

• CVE-2021-45485
• CVE-2021-45486
• CVE-2022-2588
• CVE-2022-21123
• CVE-2022-21125
• CVE-2022-21166

References

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