CVE-2026-23209 – macvlan: fix error recovery in macvlan_common_newlink()

CVE ID : CVE-2026-23209

Published : Feb. 14, 2026, 5:15 p.m. | 1 hour, 14 minutes ago

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

macvlan: fix error recovery in macvlan_common_newlink()

valis provided a nice repro to crash the kernel:

ip link add p1 type veth peer p2
ip link set address 00:00:00:00:00:20 dev p1
ip link set up dev p1
ip link set up dev p2

ip link add mv0 link p2 type macvlan mode source
ip link add invalid% link p2 type macvlan mode source macaddr add 00:00:00:00:00:20

ping -c1 -I p1 1.2.3.4

He also gave a very detailed analysis:

The issue is triggered when a new macvlan link is created with
MACVLAN_MODE_SOURCE mode and MACVLAN_MACADDR_ADD (or
MACVLAN_MACADDR_SET) parameter, lower device already has a macvlan
port and register_netdevice() called from macvlan_common_newlink()
fails (e.g. because of the invalid link name).

In this case macvlan_hash_add_source is called from
macvlan_change_sources() / macvlan_common_newlink():

This adds a reference to vlan to the port’s vlan_source_hash using
macvlan_source_entry.

vlan is a pointer to the priv data of the link that is being created.

When register_netdevice() fails, the error is returned from
macvlan_newlink() to rtnl_newlink_create():

if (ops->newlink)
err = ops->newlink(dev, &params, extack);
else
err = register_netdevice(dev);
if (err

With all that, my fix is to make sure we call macvlan_flush_sources()
regardless of @create value whenever “goto destroy_macvlan_port;”
path is taken.

Many thanks to valis for following up on this issue.

Severity: 0.0 | NA

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