RHSA-2021:3088: Red Hat Security Advisory: kernel-rt security and bug fix update

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