linux-cve-announce - CVE-2025-38110: net/mdiobus: Fix potential out-of-bounds clause 45 read/write access

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Message-ID: <2025070324-CVE-2025-38110-a9c0@gregkh>
Date: Thu,  3 Jul 2025 10:35:27 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38110: net/mdiobus: Fix potential out-of-bounds clause 45 read/write access

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

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

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

net/mdiobus: Fix potential out-of-bounds clause 45 read/write access

When using publicly available tools like 'mdio-tools' to read/write data
from/to network interface and its PHY via C45 (clause 45) mdiobus,
there is no verification of parameters passed to the ioctl and
it accepts any mdio address.
Currently there is support for 32 addresses in kernel via PHY_MAX_ADDR define,
but it is possible to pass higher value than that via ioctl.
While read/write operation should generally fail in this case,
mdiobus provides stats array, where wrong address may allow out-of-bounds
read/write.

Fix that by adding address verification before C45 read/write operation.
While this excludes this access from any statistics, it improves security of
read/write operation.

The Linux kernel CVE team has assigned CVE-2025-38110 to this issue.


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

	Issue introduced in 6.3 with commit 4e4aafcddbbfcdd6eed5780e190fcbfac8b4685a and fixed in 6.6.94 with commit abb0605ca00979a49572a6516f6db22c3dc57223
	Issue introduced in 6.3 with commit 4e4aafcddbbfcdd6eed5780e190fcbfac8b4685a and fixed in 6.12.34 with commit 31bf7b2b92563a352788cf9df3698682f659bacc
	Issue introduced in 6.3 with commit 4e4aafcddbbfcdd6eed5780e190fcbfac8b4685a and fixed in 6.15.3 with commit 4ded22f7f3ce9714ed72c3e9c68fea1cb9388ae7
	Issue introduced in 6.3 with commit 4e4aafcddbbfcdd6eed5780e190fcbfac8b4685a and fixed in 6.16-rc2 with commit 260388f79e94fb3026c419a208ece8358bb7b555

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-2025-38110
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/phy/mdio_bus.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/abb0605ca00979a49572a6516f6db22c3dc57223
	https://git.kernel.org/stable/c/31bf7b2b92563a352788cf9df3698682f659bacc
	https://git.kernel.org/stable/c/4ded22f7f3ce9714ed72c3e9c68fea1cb9388ae7
	https://git.kernel.org/stable/c/260388f79e94fb3026c419a208ece8358bb7b555