linux-cve-announce - CVE-2025-38149: net: phy: clear phydev->devlink when the link is deleted

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Message-ID: <2025070336-CVE-2025-38149-0dad@gregkh>
Date: Thu,  3 Jul 2025 10:36:06 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38149: net: phy: clear phydev->devlink when the link is deleted

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

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

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

net: phy: clear phydev->devlink when the link is deleted

There is a potential crash issue when disabling and re-enabling the
network port. When disabling the network port, phy_detach() calls
device_link_del() to remove the device link, but it does not clear
phydev->devlink, so phydev->devlink is not a NULL pointer. Then the
network port is re-enabled, but if phy_attach_direct() fails before
calling device_link_add(), the code jumps to the "error" label and
calls phy_detach(). Since phydev->devlink retains the old value from
the previous attach/detach cycle, device_link_del() uses the old value,
which accesses a NULL pointer and causes a crash. The simplified crash
log is as follows.

[   24.702421] Call trace:
[   24.704856]  device_link_put_kref+0x20/0x120
[   24.709124]  device_link_del+0x30/0x48
[   24.712864]  phy_detach+0x24/0x168
[   24.716261]  phy_attach_direct+0x168/0x3a4
[   24.720352]  phylink_fwnode_phy_connect+0xc8/0x14c
[   24.725140]  phylink_of_phy_connect+0x1c/0x34

Therefore, phydev->devlink needs to be cleared when the device link is
deleted.

The Linux kernel CVE team has assigned CVE-2025-38149 to this issue.


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

	Issue introduced in 6.2 with commit bc66fa87d4fda9053a8145e5718fc278c2b88253 and fixed in 6.6.94 with commit 363fdf2777423ad346d781f09548cca14877f729
	Issue introduced in 6.2 with commit bc66fa87d4fda9053a8145e5718fc278c2b88253 and fixed in 6.12.34 with commit ddc654e89ace723b78c34911c65243accbc9b75c
	Issue introduced in 6.2 with commit bc66fa87d4fda9053a8145e5718fc278c2b88253 and fixed in 6.15.3 with commit 034bc4a2a72dea2cfcaf24c6bae03c38ad5a0b87
	Issue introduced in 6.2 with commit bc66fa87d4fda9053a8145e5718fc278c2b88253 and fixed in 6.16-rc1 with commit 0795b05a59b1371b18ffbf09d385296b12e9f5d5

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-2025-38149
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/phy_device.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/363fdf2777423ad346d781f09548cca14877f729
	https://git.kernel.org/stable/c/ddc654e89ace723b78c34911c65243accbc9b75c
	https://git.kernel.org/stable/c/034bc4a2a72dea2cfcaf24c6bae03c38ad5a0b87
	https://git.kernel.org/stable/c/0795b05a59b1371b18ffbf09d385296b12e9f5d5