CVE-2026-64078: netfilter: x_tables: add and use xtables_unregister_table_exit

CVE-2026-64078: netfilter: x_tables: add and use xtables_unregister_table_exit

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

netfilter: x_tables: add and use xtables_unregister_table_exit

Previous change added xtables_unregister_table_pre_exit to detach the
table from the packetpath and to unlink it from the active table list.
In case of rmmod, userspace that is doing set/getsockopt for this table
will not be able to re-instantiate the table:
 1. The larval table has been removed already
 2. existing instantiated table is no longer on the xt pernet table list.

This adds the second stage helper:

unlink the table from the dying list, free the hook ops (if any) and do
the audit notification.  It replaces xt_unregister_table().

The Linux kernel CVE team has assigned CVE-2026-64078 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.15 with commit fdacd57c79b79a03c7ca88f706ad9fb7b46831c1 and fixed in 6.18.34 with commit 86ee5bc9c0f0e652e19f395675a432de11b75514
	Issue introduced in 5.15 with commit fdacd57c79b79a03c7ca88f706ad9fb7b46831c1 and fixed in 7.0.11 with commit 8026e5163cca1d1db436c7bfb89ddea8b5e8c2cf
	Issue introduced in 5.15 with commit fdacd57c79b79a03c7ca88f706ad9fb7b46831c1 and fixed in 7.1 with commit b4597d5fd7d2f8cebfffd40dffb5e003cc78964c

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-64078
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	include/linux/netfilter/x_tables.h
	net/ipv4/netfilter/arp_tables.c
	net/ipv4/netfilter/ip_tables.c
	net/ipv4/netfilter/iptable_nat.c
	net/ipv6/netfilter/ip6_tables.c
	net/ipv6/netfilter/ip6table_nat.c
	net/netfilter/x_tables.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/86ee5bc9c0f0e652e19f395675a432de11b75514
	https://git.kernel.org/stable/c/8026e5163cca1d1db436c7bfb89ddea8b5e8c2cf
	https://git.kernel.org/stable/c/b4597d5fd7d2f8cebfffd40dffb5e003cc78964c