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:
<quote valis>
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, ¶ms, extack);
else
err = register_netdevice(dev);
if (err < 0) {
free_netdev(dev);
goto out;
}
and free_netdev() is called, causing a kvfree() on the struct
net_device that is still referenced in the source entry attached to
the lower device's macvlan port.
Now all packets sent on the macvlan port with a matching source mac
address will trigger a use-after-free in macvlan_forward_source().
</quote valis>
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.
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:
<quote valis>
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, ¶ms, extack);
else
err = register_netdevice(dev);
if (err < 0) {
free_netdev(dev);
goto out;
}
and free_netdev() is called, causing a kvfree() on the struct
net_device that is still referenced in the source entry attached to
the lower device's macvlan port.
Now all packets sent on the macvlan port with a matching source mac
address will trigger a use-after-free in macvlan_forward_source().
</quote valis>
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.
Metrics
Affected Vendors & Products
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Fixes
Solution
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Workaround
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References
History
Sat, 14 Feb 2026 16:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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: <quote valis> 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, ¶ms, extack); else err = register_netdevice(dev); if (err < 0) { free_netdev(dev); goto out; } and free_netdev() is called, causing a kvfree() on the struct net_device that is still referenced in the source entry attached to the lower device's macvlan port. Now all packets sent on the macvlan port with a matching source mac address will trigger a use-after-free in macvlan_forward_source(). </quote valis> 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. | |
| Title | macvlan: fix error recovery in macvlan_common_newlink() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-02-14T16:27:31.175Z
Reserved: 2026-01-13T15:37:45.986Z
Link: CVE-2026-23209
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-02-14T17:15:58.803
Modified: 2026-02-14T17:15:58.803
Link: CVE-2026-23209
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.