RHSA-2021:3088 - Security Advisory

Topic

An update for kernel-rt is now available for Red Hat Enterprise Linux 8.

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: race condition in net/can/bcm.c leads to local privilege escalation (CVE-2021-3609)
• kernel: Improper handling of VM_IO|VM_PFNMAP vmas in KVM can bypass RO checks (CVE-2021-22543)
• kernel: out-of-bounds write in xt_compat_target_from_user() in net/netfilter/x_tables.c (CVE-2021-22555)

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):

• kernel-rt: update RT source tree to the RHEL-8.4.z source tree (BZ#1985050)
• kernel-rt: Merge mm/memcg: Fix kmem_cache_alloc() performance regression (BZ#1987102)

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 x86_64 - Extended Update Support Extension 8.8 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support Extension 8.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support Extension 8.4 x86_64
• Red Hat Enterprise Linux for Real Time 8 x86_64
• Red Hat Enterprise Linux for Real Time for NFV 8 x86_64
• Red Hat Enterprise Linux for Real Time - Telecommunications Update Service 8.8 x86_64
• Red Hat Enterprise Linux for Real Time - Telecommunications Update Service 8.6 x86_64
• 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 8.8 x86_64
• Red Hat Enterprise Linux for Real Time for NFV - Telecommunications Update Service 8.6 x86_64
• Red Hat Enterprise Linux for Real Time for NFV - Telecommunications Update Service 8.4 x86_64

Fixes

• BZ - 1965461 - CVE-2021-22543 kernel: Improper handling of VM_IO|VM_PFNMAP vmas in KVM can bypass RO checks
• BZ - 1971651 - CVE-2021-3609 kernel: race condition in net/can/bcm.c leads to local privilege escalation
• BZ - 1980101 - CVE-2021-22555 kernel: out-of-bounds write in xt_compat_target_from_user() in net/netfilter/x_tables.c

CVEs

• CVE-2021-3609
• CVE-2021-22543
• CVE-2021-22555

References

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