CVE-2026-64120

/// Technical description

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

net: ethtool: fix NULL pointer dereference in phy_reply_size

In phy_prepare_data(), several strings such as 'name', 'drvname',

'upstream_sfp_name', and 'downstream_sfp_name' are allocated using

kstrdup(). However, these allocations were not checked for failure.

If kstrdup() fails for 'name', it returns NULL while the function

continues. This leads to a kernel NULL pointer dereference and panic

later in phy_reply_size() when it unconditionally calls strlen() on

the NULL pointer.

While other strings like 'upstream_sfp_name' might be checked before

access in certain code paths, failing to handle these allocations

consistently can lead to incomplete data reporting or hidden bugs.

Fix this by adding proper NULL checks for all kstrdup() calls in

phy_prepare_data() and implement a centralized error handling path

using goto labels to ensure all previously allocated resources are

freed on failure.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References