CVE-2025-23131

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

dlm: prevent NPD when writing a positive value to event_done

douevent returns the value written to eventdone. In case it is a positive value, newlockspace would undo all the work, and lockspace would not be set. _dlmnewlockspace, however, would treat that positive value as a success due to commit 8511a2728ab8 ("dlm: fix use count with multiple joins").

Down the line, devicecreatelockspace would pass that NULL lockspace to dlmfindlockspace_local, leading to a NULL pointer dereference.

Treating such positive values as successes prevents the problem. Given this has been broken for so long, this is unlikely to break userspace expectations.