Use-after-free in nft_verdict_dump due to a race between set GC and transaction
CVE: CVE-2023-4244
Component: kernel
CWE: CWE-416
Severity: Moderate
CVSS v3: 7.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Release date: 2023-08-28T00:00:00+00:00

A use-after-free flaw was found in the Linux kernel’s nftables sub-component due to a race problem between the set GC and transaction in the Linux Kernel. This flaw allows a local attacker to crash the system due to a missing call to `nft_set_elem_mark_busy`, causing double deactivation of the element and possibly leading to a kernel information leak problem.

Statement: Exploiting this flaw will require CAP_NET_ADMIN access privilege in any user or network namespace.

And,

On non-containerized deployments of Red Hat Enterprise Linux, you can disable user namespaces by setting user.max_user_namespaces to 0:

$ echo "user.max_user_namespaces=0" > /etc/sysctl.d/userns.conf
$ sysctl -p /etc/sysctl.d/userns.conf

On containerized deployments, such as Red Hat OpenShift Container Platform, do not use this mitigation as the functionality is needed to be enabled.

Remediation:
For OpenShift Container Platform 4.13 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this errata update:

https://docs.openshift.com/container-platform/4.13/release_notes/ocp-4-13-release-notes.html

For Red Hat OpenShift Logging 5.8, see the following instructions to apply this update:

https://docs.openshift.com/container-platform/4.13/logging/cluster-logging-upgrading.html
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.
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.
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.
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.
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.
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.
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.
Mitigation for this issue is to skip loading the affected module "nftables" onto the system till we have a fix available, this can be done by a blacklist mechanism, this will ensure the driver is not loaded at the boot time.
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How do I blacklist a kernel module to prevent it from loading automatically?
https://access.redhat.com/solutions/41278 
~~~