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=====================================================================
                   Red Hat Security Advisory

Synopsis:          Important: kernel-rt security and bug fix update
Advisory ID:       RHSA-2021:3088-01
Product:           Red Hat Enterprise Linux
Advisory URL:      https://access.redhat.com/errata/RHSA-2021:3088
Issue date:        2021-08-10
CVE Names:         CVE-2021-3609 CVE-2021-22543 CVE-2021-22555 
=====================================================================

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 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.

2. Relevant releases/architectures:

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

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/):

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

6. Package List:

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

Source:
kernel-rt-4.18.0-305.12.1.rt7.84.el8_4.src.rpm

x86_64:
kernel-rt-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-core-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debug-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debug-core-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debug-debuginfo-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debug-devel-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debug-kvm-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debug-modules-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debug-modules-extra-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debuginfo-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debuginfo-common-x86_64-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-devel-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-kvm-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-modules-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-modules-extra-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm

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

Source:
kernel-rt-4.18.0-305.12.1.rt7.84.el8_4.src.rpm

x86_64:
kernel-rt-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-core-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debug-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debug-core-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debug-debuginfo-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debug-devel-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debug-modules-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debug-modules-extra-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debuginfo-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-debuginfo-common-x86_64-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-devel-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-modules-4.18.0-305.12.1.rt7.84.el8_4.x86_64.rpm
kernel-rt-modules-extra-4.18.0-305.12.1.rt7.84.el8_4.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-2021-3609
https://access.redhat.com/security/cve/CVE-2021-22543
https://access.redhat.com/security/cve/CVE-2021-22555
https://access.redhat.com/security/updates/classification/#important

8. Contact:

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

Copyright 2021 Red Hat, Inc.
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