linux-kernel - [PATCH v2 0/2] ipc,namespace: fix free vs allocation race

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 26 Jan 2023 20:15:33 -0500
From:   Rik van Riel <riel@...riel.com>
To:     viro@...iv.linux.org.uk, linux-kernel@...r.kernel.org,
        kernel-team@...a.com, linux-fsdevel@...r.kernel.org,
        gscrivan@...hat.com
Subject: [PATCH v2 0/2] ipc,namespace: fix free vs allocation race

The IPC namespace code frees ipc_namespace structures asynchronously,
via a work queue item. This results in ipc_namespace structures being
freed very slowly, and the allocation path getting false failures
since the to-be-freed ipc_namespace structures have not been freed
yet.

Fix that by having the allocator wait when there are ipc_namespace
structures pending to be freed.

Also speed up the freeing of ipc_namespace structures. We had some
discussions about this last year, and ended up trying out various
"nicer" ideas that did not work, so I went back to the original,
with Al Viro's suggestion for a helper function:

https://lore.kernel.org/all/Yg8StKzTWh+7FLuA@zeniv-ca.linux.org.uk/

This series fixes both the false allocation failures, and the slow
freeing of ipc_namespace structures.

v2: a few more fs/namespace.c cleanups suggested by Al Viro (thank you!)