CVE-2025-40242

A flaw was found in the Linux kernel’s Global File System 2 implementation affecting distributed lock manager (DLM) handling in the gdlm_put_lock() function. During an unmount operation, if the DFL_UNMOUNT flag is set but the lockspace has not yet been fully released, remote callbacks (gdlm_ast() or gdlm_bast()) may still be invoked. This can result in dereferencing a freed glock (GFS2 lock) object, leading to undefined behavior and potential kernel instability or crashes.

Red Hat has rated this vulnerability as Moderate severity because triggering the race condition requires an active cluster configuration with shared storage and specific timing during a filesystem unmount. GFS2 is not mounted by default in Red Hat Enterprise Linux and is typically utilized only within specialized high-availability clustering environments. Exploitation is constrained to nodes participating in the cluster lockspace and primarily results in a denial of service through system crashes, without compromising data confidentiality or integrity.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.