CVE-2025-38668: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-38668 is a vulnerability in the Linux kernel's regulator core component, discovered and disclosed on August 22, 2025. The vulnerability affects the regulator subsystem's handling of coupling data during unbind operations. This issue impacts various Linux kernel versions, particularly affecting Red Hat Enterprise Linux 9 and 10 distributions (Red Hat CVE).

The vulnerability stems from a failure to reset couplingdesc.ncoupled after freeing coupledrdevs, which can lead to NULL pointer dereference when regulators are accessed post-unbind. This issue can be triggered during runtime PM or other regulator operations that rely on coupling metadata. For example, on ridesx4 systems, unbinding the 'reg-dummy' platform device triggers a panic in regulatorlock_recursive() due to stale coupling state. The vulnerability has been assigned a CVSS v3.1 score of 7.0, indicating moderate severity (Red Hat CVE).

When exploited, this vulnerability can cause system crashes through NULL pointer dereference, potentially leading to denial of service conditions. The impact is particularly relevant during runtime power management operations or when performing regulator-related operations that depend on coupling metadata (NVD).

The fix involves ensuring that ncoupled is set to 0 to prevent access to invalid pointers after freeing coupledrdevs. This patch has been integrated into the Linux kernel. Affected systems should be updated to versions containing the fix. Red Hat has marked this as affecting RHEL 9 and 10, with patches available through their update channels (Red Hat CVE).