CVE-2026-74474: vxlan: use pskb_network_may_pull() for transmit path header pulls

CVE-2026-74474: vxlan: use pskb_network_may_pull() for transmit path header pulls

[Greg Kroah-Hartman]

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

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

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

vxlan: use pskb_network_may_pull() for transmit path header pulls

In vxlan_xmit(), arp_reduce(), and vxlan_mdb_entry_skb_get(), pskb_may_pull() was
being called to verify the availability of network layer headers (ARP, IPv6/ND,
IP/IPv6 MDB keys).

However, during transmit skb->data points to the MAC header, so skb_network_offset(skb)
is ETH_HLEN (14 bytes). Using pskb_may_pull(skb, len) only checks len bytes from skb->data
rather than skb_network_offset(skb) + len, which can leave part of the network header
in non-linear frags.

Replace these remaining pskb_may_pull() calls with pskb_network_may_pull() to properly
account for the MAC header offset.

The Linux kernel CVE team has assigned CVE-2026-74474 to this issue.


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

	Issue introduced in 3.8 with commit e4f67addf158f98f8197e08974966b18480dc751 and fixed in 6.18.44 with commit 94dee751aad627b3645d424b5d0c736d394573e9
	Issue introduced in 3.8 with commit e4f67addf158f98f8197e08974966b18480dc751 and fixed in 7.1.8 with commit 7076a34b6e33315dc160b4612bfea1c597495585
	Issue introduced in 3.8 with commit e4f67addf158f98f8197e08974966b18480dc751 and fixed in 7.2-rc6 with commit b9553558b48db54ac9273e6b98d7263ef5c1a329

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-2026-74474
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/vxlan/vxlan_core.c
	drivers/net/vxlan/vxlan_mdb.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/94dee751aad627b3645d424b5d0c736d394573e9
	https://git.kernel.org/stable/c/7076a34b6e33315dc160b4612bfea1c597495585
	https://git.kernel.org/stable/c/b9553558b48db54ac9273e6b98d7263ef5c1a329