CVE-2026-72463: xfrm: Fix dev use-after-free in xfrm async resumption

CVE-2026-72463: xfrm: Fix dev use-after-free in xfrm async resumption

[Greg Kroah-Hartman]

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

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

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

xfrm: Fix dev use-after-free in xfrm async resumption

xfrm async resumption hold skb->dev refcnt until after transport_finish.
However, xfrm_rcv_cb may modify skb->dev to tunnel dev without taking
device reference, such as vti_rcv_cb. The subsequent async resumption
will decrement the tunnel device's reference count, which lead to uaf
of tunnel dev and refcnt leak of orig dev as below:

unregister_netdevice: waiting for vti1 to become free. Usage count = -2

Stash the original skb->dev to fix refcnt imbalance. The new skb->dev set
by xfrm_rcv_cb can race with device teardown. Extend rcu protection over
xfrm_rcv_cb and transport_finish to prevent races.

The Linux kernel CVE team has assigned CVE-2026-72463 to this issue.


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

	Issue introduced in 7.0 with commit 1c428b03840094410c5fb6a5db30640486bbbfcb and fixed in 7.1.5 with commit 63a30015199912bd5055bead8001b1ae68a67cdb
	Issue introduced in 7.0 with commit 1c428b03840094410c5fb6a5db30640486bbbfcb and fixed in 7.2-rc1 with commit 8045c0df98d4f14c54e5cb875f1c9c0ce89fe4ff
	Issue introduced in 6.12.94 with commit 4236c30b437b80f673b9e08c8fae38b8d471ac9e
	Issue introduced in 6.18.23 with commit 0f451b43c88bf2b9c038b414be580efee42e031b
	Issue introduced in 6.19.13 with commit 5002beda5cac69d522dc54da0d5d463ed9c963d2

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-2026-72463
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/ipv4/xfrm4_input.c
	net/ipv6/xfrm6_input.c
	net/xfrm/xfrm_input.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/63a30015199912bd5055bead8001b1ae68a67cdb
	https://git.kernel.org/stable/c/8045c0df98d4f14c54e5cb875f1c9c0ce89fe4ff