CVE-2026-64123: net: hsr: defer node table free until after RCU readers

From: Greg Kroah-Hartman <[email protected]>

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

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

net: hsr: defer node table free until after RCU readers

HSR node-list and node-status generic-netlink operations run under
rcu_read_lock(). They walk hsr->node_db through hsr_get_next_node() and
hsr_get_node_data(), but RTM_DELLINK teardown removes the same node table
with plain list_del() and frees each node immediately.

That lets a generic-netlink reader hold a struct hsr_node pointer across
hsr_dellink(). In a KASAN build, widening the reader window after
hsr_get_next_node() obtains the node reproduces a slab-use-after-free
when the reader copies node->macaddress_A; the freeing stack is
hsr_del_nodes() from hsr_dellink().

Use list_del_rcu() and defer the free through the existing
hsr_free_node_rcu() callback. This matches the lifetime rule used by the
HSR prune paths, which already delete nodes with list_del_rcu() and
call_rcu().

The Linux kernel CVE team has assigned CVE-2026-64123 to this issue.


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

	Issue introduced in 5.3 with commit b9a1e627405d68d475a3c1f35e685ccfb5bbe668 and fixed in 5.10.259 with commit 0ea70fb46940620848c08d9d399455c9e82fecdb
	Issue introduced in 5.3 with commit b9a1e627405d68d475a3c1f35e685ccfb5bbe668 and fixed in 5.15.210 with commit 8be6685cdd1255bcc85f9b59e4bfc313aefc5c1b
	Issue introduced in 5.3 with commit b9a1e627405d68d475a3c1f35e685ccfb5bbe668 and fixed in 6.1.176 with commit c5580114e0492bcd2e0a37613ed4c311e3fa3d4d
	Issue introduced in 5.3 with commit b9a1e627405d68d475a3c1f35e685ccfb5bbe668 and fixed in 6.6.143 with commit 7713f4aafb577ff49fa67f0488d9c7dddc64d6ce
	Issue introduced in 5.3 with commit b9a1e627405d68d475a3c1f35e685ccfb5bbe668 and fixed in 6.12.93 with commit 6324423a8e6591f41a16c09a8f9a84e554ac147c
	Issue introduced in 5.3 with commit b9a1e627405d68d475a3c1f35e685ccfb5bbe668 and fixed in 7.0.11 with commit 8c3af18bb0d7c921a5219194037509463eb2ffde
	Issue introduced in 5.3 with commit b9a1e627405d68d475a3c1f35e685ccfb5bbe668 and fixed in 7.1 with commit aaec7096f9961eb223b5b149abe9495525c205d9
	Issue introduced in 5.2.12 with commit 08523d5a2f4a9e4202e00d282c164d453cabe2d2

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-2026-64123
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:
	net/hsr/hsr_framereg.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/0ea70fb46940620848c08d9d399455c9e82fecdb
	https://git.kernel.org/stable/c/8be6685cdd1255bcc85f9b59e4bfc313aefc5c1b
	https://git.kernel.org/stable/c/c5580114e0492bcd2e0a37613ed4c311e3fa3d4d
	https://git.kernel.org/stable/c/7713f4aafb577ff49fa67f0488d9c7dddc64d6ce
	https://git.kernel.org/stable/c/6324423a8e6591f41a16c09a8f9a84e554ac147c
	https://git.kernel.org/stable/c/8c3af18bb0d7c921a5219194037509463eb2ffde
	https://git.kernel.org/stable/c/aaec7096f9961eb223b5b149abe9495525c205d9