CVE-2024-38570

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.