linux-cve-announce - CVE-2026-23103: ipvlan: Make the addrs

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Message-ID: <2026020429-CVE-2026-23103-63b3@gregkh>
Date: Wed,  4 Feb 2026 17:15:02 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2026-23103: ipvlan: Make the addrs_lock be per port

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

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

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

ipvlan: Make the addrs_lock be per port

Make the addrs_lock be per port, not per ipvlan dev.

Initial code seems to be written in the assumption,
that any address change must occur under RTNL.
But it is not so for the case of IPv6. So

1) Introduce per-port addrs_lock.

2) It was needed to fix places where it was forgotten
to take lock (ipvlan_open/ipvlan_close)

This appears to be a very minor problem though.
Since it's highly unlikely that ipvlan_add_addr() will
be called on 2 CPU simultaneously. But nevertheless,
this could cause:

1) False-negative of ipvlan_addr_busy(): one interface
iterated through all port->ipvlans + ipvlan->addrs
under some ipvlan spinlock, and another added IP
under its own lock. Though this is only possible
for IPv6, since looks like only ipvlan_addr6_event() can be
called without rtnl_lock.

2) Race since ipvlan_ht_addr_add(port) is called under
different ipvlan->addrs_lock locks

This should not affect performance, since add/remove IP
is a rare situation and spinlock is not taken on fast
paths.

The Linux kernel CVE team has assigned CVE-2026-23103 to this issue.


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

	Issue introduced in 4.17 with commit 8230819494b3bf284ca7262ac5f877333147b937 and fixed in 6.6.122 with commit 04ba6de6eff61238e5397c14ac26a6578c7735a5
	Issue introduced in 4.17 with commit 8230819494b3bf284ca7262ac5f877333147b937 and fixed in 6.12.68 with commit 1f300c10d92c547c3a7d978e1212ff52f18256ed
	Issue introduced in 4.17 with commit 8230819494b3bf284ca7262ac5f877333147b937 and fixed in 6.18.8 with commit 6a81e2db096913d7e43aada1c350c1282e76db39
	Issue introduced in 4.17 with commit 8230819494b3bf284ca7262ac5f877333147b937 and fixed in 6.19-rc7 with commit d3ba32162488283c0a4c5bedd8817aec91748802

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-2026-23103
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:
	drivers/net/ipvlan/ipvlan.h
	drivers/net/ipvlan/ipvlan_core.c
	drivers/net/ipvlan/ipvlan_main.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/04ba6de6eff61238e5397c14ac26a6578c7735a5
	https://git.kernel.org/stable/c/1f300c10d92c547c3a7d978e1212ff52f18256ed
	https://git.kernel.org/stable/c/6a81e2db096913d7e43aada1c350c1282e76db39
	https://git.kernel.org/stable/c/d3ba32162488283c0a4c5bedd8817aec91748802