Important: kernel-rt security and bug fix update

Topic

An update for kernel-rt is now available for Red Hat Enterprise Linux 8.2 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):

• kernel: Use After Free in unix_gc() which could result in a local privilege escalation (CVE-2021-0920)
• kernel: use-after-free in RDMA listen() (CVE-2021-4028)
• kernel: xfs: raw block device data leak in XFS_IOC_ALLOCSP IOCTL (CVE-2021-4155)

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):

• kernnel-rt-debug: do not call blocking ops when !TASK_RUNNING; state=1 set at [<0000000050e86018>] handle_userfault+0x530/0x1820 (BZ#2029420)
• kernel-rt: update RT source tree to the latest RHEL-8.2.z15 Batch (BZ#2046275)

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 8.2 x86_64
• Red Hat Enterprise Linux for Real Time for NFV - Telecommunications Update Service 8.2 x86_64

Fixes

• BZ - 2027201 - CVE-2021-4028 kernel: use-after-free in RDMA listen()
• BZ - 2031930 - CVE-2021-0920 kernel: Use After Free in unix_gc() which could result in a local privilege escalation
• BZ - 2034813 - CVE-2021-4155 kernel: xfs: raw block device data leak in XFS_IOC_ALLOCSP IOCTL

CVEs

• CVE-2021-0920
• CVE-2021-4028
• CVE-2021-4155

References

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