linux-cve-announce - CVE-2022-49776: macvlan: enforce a consistent minimal mtu

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Message-ID: <2025050117-CVE-2022-49776-6054@gregkh>
Date: Thu,  1 May 2025 16:09:26 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-49776: macvlan: enforce a consistent minimal mtu

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

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

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

macvlan: enforce a consistent minimal mtu

macvlan should enforce a minimal mtu of 68, even at link creation.

This patch avoids the current behavior (which could lead to crashes
in ipv6 stack if the link is brought up)

$ ip link add macvlan1 link eno1 mtu 8 type macvlan  # This should fail !
$ ip link sh dev macvlan1
5: macvlan1@...1: <BROADCAST,MULTICAST> mtu 8 qdisc noop
    state DOWN mode DEFAULT group default qlen 1000
    link/ether 02:47:6c:24:74:82 brd ff:ff:ff:ff:ff:ff
$ ip link set macvlan1 mtu 67
Error: mtu less than device minimum.
$ ip link set macvlan1 mtu 68
$ ip link set macvlan1 mtu 8
Error: mtu less than device minimum.

The Linux kernel CVE team has assigned CVE-2022-49776 to this issue.


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

	Issue introduced in 4.10 with commit 91572088e3fdbf4fe31cf397926d8b890fdb3237 and fixed in 4.14.300 with commit d2fee7d121d189c6dc905b727d60e7043a6655bb
	Issue introduced in 4.10 with commit 91572088e3fdbf4fe31cf397926d8b890fdb3237 and fixed in 4.19.267 with commit 650137a7c0b2892df2e5b0bc112d7b09a78c93c8
	Issue introduced in 4.10 with commit 91572088e3fdbf4fe31cf397926d8b890fdb3237 and fixed in 5.4.225 with commit a62aa84fe19eb24d083d600a074c009a0a66d4f3
	Issue introduced in 4.10 with commit 91572088e3fdbf4fe31cf397926d8b890fdb3237 and fixed in 5.10.156 with commit e929ec98c0c3b10d9c07f3776df0c1a02d7a763e
	Issue introduced in 4.10 with commit 91572088e3fdbf4fe31cf397926d8b890fdb3237 and fixed in 5.15.80 with commit e41cbf98df22d08402e65174d147cbb187fe1a33
	Issue introduced in 4.10 with commit 91572088e3fdbf4fe31cf397926d8b890fdb3237 and fixed in 6.0.10 with commit 2b055c719d8f94c15ec9b7659978133030c6a353
	Issue introduced in 4.10 with commit 91572088e3fdbf4fe31cf397926d8b890fdb3237 and fixed in 6.1 with commit b64085b00044bdf3cd1c9825e9ef5b2e0feae91a

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-2022-49776
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/macvlan.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/d2fee7d121d189c6dc905b727d60e7043a6655bb
	https://git.kernel.org/stable/c/650137a7c0b2892df2e5b0bc112d7b09a78c93c8
	https://git.kernel.org/stable/c/a62aa84fe19eb24d083d600a074c009a0a66d4f3
	https://git.kernel.org/stable/c/e929ec98c0c3b10d9c07f3776df0c1a02d7a763e
	https://git.kernel.org/stable/c/e41cbf98df22d08402e65174d147cbb187fe1a33
	https://git.kernel.org/stable/c/2b055c719d8f94c15ec9b7659978133030c6a353
	https://git.kernel.org/stable/c/b64085b00044bdf3cd1c9825e9ef5b2e0feae91a