[RHSA-2021:5241-05] Moderate: kernel-rt security and bug fix update

[Security announcements for all Red Hat products and services.]

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                   Red Hat Security Advisory

Synopsis:          Moderate: kernel-rt security and bug fix update
Advisory ID:       RHSA-2021:5241-01
Product:           Red Hat Enterprise Linux
Advisory URL:      https://access.redhat.com/errata/RHSA-2021:5241
Issue date:        2021-12-21
CVE Names:         CVE-2021-20321 
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1. Summary:

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 Moderate. 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.

2. Relevant releases/architectures:

Red Hat Enterprise Linux Real Time for NFV (v. 8) - x86_64
Red Hat Enterprise Linux for Real Time (v. 8) - x86_64

3. 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: In Overlayfs missing a check for a negative dentry before calling
vfs_rename() (CVE-2021-20321)

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-8.5.z1 source tree
(BZ#2023988)

* [rt] RHEL-8.6: disable KASAN, KCSAN and UBSAN for kernel-rt (BZ#2026384)

4. 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.

5. Bugs fixed (https://bugzilla.redhat.com/):

2013242 - CVE-2021-20321 kernel: In Overlayfs missing a check for a negative dentry before calling vfs_rename()

6. Package List:

Red Hat Enterprise Linux Real Time for NFV (v. 8):

Source:
kernel-rt-4.18.0-348.7.1.rt7.137.el8_5.src.rpm

x86_64:
kernel-rt-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-core-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debug-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debug-core-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debug-debuginfo-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debug-devel-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debug-kvm-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debug-modules-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debug-modules-extra-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debuginfo-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debuginfo-common-x86_64-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-devel-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-kvm-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-modules-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-modules-extra-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm

Red Hat Enterprise Linux for Real Time (v. 8):

Source:
kernel-rt-4.18.0-348.7.1.rt7.137.el8_5.src.rpm

x86_64:
kernel-rt-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-core-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debug-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debug-core-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debug-debuginfo-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debug-devel-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debug-modules-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debug-modules-extra-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debuginfo-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-debuginfo-common-x86_64-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-devel-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-modules-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm
kernel-rt-modules-extra-4.18.0-348.7.1.rt7.137.el8_5.x86_64.rpm

These packages are GPG signed by Red Hat for security.  Our key and
details on how to verify the signature are available from
https://access.redhat.com/security/team/key/

7. References:

https://access.redhat.com/security/cve/CVE-2021-20321
https://access.redhat.com/security/updates/classification/#moderate

8. Contact:

The Red Hat security contact is <secalert at redhat.com>. More contact
details at https://access.redhat.com/security/team/contact/

Copyright 2021 Red Hat, Inc.
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