RHSA-2021:3328 - 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: out-of-bounds write in xt_compat_target_from_user() in net/netfilter/x_tables.c (CVE-2021-22555)
• kernel: race condition for removal of the HCI controller (CVE-2021-32399)
• kernel: Local privilege escalation due to incorrect BPF JIT branch displacement computation (CVE-2021-29154)
• kernel: lack a full memory barrier upon the assignment of a new table value in net/netfilter/x_tables.c and include/linux/netfilter/x_tables.h may lead to DoS (CVE-2021-29650)

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 to the latest RHEL7.9.z8 source tree (BZ#1982927)

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 - 1945388 - CVE-2021-29650 kernel: lack a full memory barrier upon the assignment of a new table value in net/netfilter/x_tables.c and include/linux/netfilter/x_tables.h may lead to DoS
• BZ - 1946684 - CVE-2021-29154 kernel: Local privilege escalation due to incorrect BPF JIT branch displacement computation
• BZ - 1970807 - CVE-2021-32399 kernel: race condition for removal of the HCI controller
• BZ - 1980101 - CVE-2021-22555 kernel: out-of-bounds write in xt_compat_target_from_user() in net/netfilter/x_tables.c

CVEs

• CVE-2021-22555
• CVE-2021-29154
• CVE-2021-29650
• CVE-2021-32399

References

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