CVE-2025-38149: linux kernel Null Dereference — Fix

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.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	6.2 — 6.6.94
linux	linux_kernel	6.7 — 6.12.34
linux	linux_kernel	6.13 — 6.15.3

References

Advisories & Patches

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

Frequently Asked Questions

What is CVE-2025-38149? +

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. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-38149? +

CVE-2025-38149 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-38149? +

CVE-2025-38149 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-38149? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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