CVE-2024-38570: gfs2: Fix potential glock use-after-free on unmount

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-06-19 · updated 2026-10-30
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: gfs2: Fix potential glock use-after-free on unmount When a DLM lockspace is released and there ares still locks in that lockspace, DLM will unlock those locks automatically. Commit fb6791d100d1b started exploiting this behavior to speed up filesystem unmount: gfs2 would simply free glocks it didn't want to unlock and then release the lockspace. This didn't take the bast callbacks for asynchronous lock contention notifications into account, which remain active until until a lock is unlocked or its lockspace is released. To prevent those callbacks from accessing deallocated objects, put the glocks that should not be unlocked on the sd_dead_glocks list, release the lockspace, and only then free those glocks. As an additional measure, ignore unexpected ast and bast callbacks if the receiving glock is dead.

Affected products

Linux kernel: from 3.8 before 6.6.33; from 6.7 before 6.8.12; from 6.9 before 6.9.3 — fixed in 6.6.33, 6.8.12, 6.9.3
Linux: 3.8 — fixed in 6.10

How to fix

Upgrade to a fixed version: Linux kernel 6.6.33, 6.8.12, 6.9.3; Linux 6.10. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2024-38570 or the next vulnerability affects your stack