CVE-2025-39872

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

hsr: hold rcu and dev lock for hsr_get_port_ndev

hsr_get_port_ndev calls hsr_for_each_port, which need to hold rcu lock. On the other hand, before return the port device, we need to hold the device reference to avoid UaF in the caller function.

This flaw does not present an operational risk to Red Hat environments because the vulnerable High-availability Seamless Redundancy (HSR) code is not present in supported Red Hat Enterprise Linux releases. In systems where this upstream networking code exists, a local user could exploit missing reference tracking to trigger a use-after-free condition, leading to a system crash or elevated privileges. Because the commit that introduced this flaw was merged in newer upstream kernels, Red Hat kernels remain unaffected.