The Linux kernel’s ethtool interface contains a flaw that allows an offline self test to bring a network device down and back up without holding the required rtnl_lock when the driver is ops‑locked. This missing lock causes close and open operations to race against the kernel’s lock validation logic, producing lockdep warnings and triggering assertion failures in functions such as __dev_close_many. The outcome is a device that may become unstable or non‑operational, effectively denying service to the affected network interface.

This issue affects Linux kernel implementations that include ops‑locked network drivers performing offline self tests, notably the fbnic and bnxt drivers. Any kernel release prior to the patch that adds an optional rtnl_lock requirement for such drivers is vulnerable. The flaw is triggered through the legacy ETHTOOL_TEST ioctl, which requires privileged (root) access.

The vulnerability lacks a CVSS score and EPSS data, and it is not listed in the CISA KEV catalog. Exploitation requires local root privileges to invoke the ETHTOOL_TEST ioctl, so it is not remotely exploitable from unprivileged users. However, an administrator or trusted automated process could intentionally or accidentally trigger the self test, leading to a local denial of service on the targeted interface. The risk is therefore considered medium to high for systems that routinely use the ETHTOOL_TEST ioctl on ops‑locked drivers, but low for typical user‑level deployments.