linux-cve-announce - CVE-2023-53516: macvlan: add forgotten nla_policy for IFLA_MACVLAN_BC

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Message-ID: <2025100131-CVE-2023-53516-ca63@gregkh>
Date: Wed,  1 Oct 2025 13:46:08 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53516: macvlan: add forgotten nla_policy for IFLA_MACVLAN_BC_CUTOFF

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

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

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

macvlan: add forgotten nla_policy for IFLA_MACVLAN_BC_CUTOFF

The previous commit 954d1fa1ac93 ("macvlan: Add netlink attribute for
broadcast cutoff") added one additional attribute named
IFLA_MACVLAN_BC_CUTOFF to allow broadcast cutfoff.

However, it forgot to describe the nla_policy at macvlan_policy
(drivers/net/macvlan.c). Hence, this suppose NLA_S32 (4 bytes) integer
can be faked as empty (0 bytes) by a malicious user, which could leads
to OOB in heap just like CVE-2023-3773.

To fix it, this commit just completes the nla_policy description for
IFLA_MACVLAN_BC_CUTOFF. This enforces the length check and avoids the
potential OOB read.

The Linux kernel CVE team has assigned CVE-2023-53516 to this issue.

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

	Issue introduced in 6.4 with commit 954d1fa1ac93aa8a66f7d9a9ba545cf7f020d348 and fixed in 6.4.8 with commit 79f44709aa7a744fbfbadd4aef678443290c6991
	Issue introduced in 6.4 with commit 954d1fa1ac93aa8a66f7d9a9ba545cf7f020d348 and fixed in 6.5 with commit 55cef78c244d0d076f5a75a35530ca63c92f4426

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-2023-53516
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/79f44709aa7a744fbfbadd4aef678443290c6991
	https://git.kernel.org/stable/c/55cef78c244d0d076f5a75a35530ca63c92f4426