linux-kernel - Re: [PATCH cgroup] https://github.com/raspberrypi/linux/issues/6631

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-prev] [day] [month] [year] [list]

Message-ID: <86cyg1bvuw.fsf@davidreaver.com>
Date: Sat, 01 Feb 2025 06:08:55 -0800
From: David Reaver <me@...idreaver.com>
To: Umar Pathan <cynexium@...il.com>
Cc: tj@...nel.org,  lizefan.x@...edance.com,  hannes@...xchg.org,
  cgroups@...r.kernel.org,  linux-kernel@...r.kernel.org,  Umar Pathan
 <cynexium@...ton.me>
Subject: Re: [PATCH cgroup] https://github.com/raspberrypi/linux/issues/6631

Umar Pathan <cynexium@...il.com> writes:

> The existing freezer propagation logic improperly reduces
> nr_frozen_descendants by an increasing 'desc' counter during unfreeze,
> leading to:
> - Premature parent cgroup unfreezing
> - Negative descendant counts
> - Broken hierarchy state consistency
>
> Scenario demonstrating the bug:
> 1. Create hierarchy A->B->C
> 2. Freeze C (A/B freeze via propagation)
> 3. Freeze A->D (separate branch)
> 4. Unfreeze C -> A incorrectly unfreezes despite frozen D
>
> Fixes: 711f763 ("freezer,cgroup: add freezer.stats subsystem")
> Signed-off-by: Umar cynexium@...il.com
> ---
>  kernel/cgroup/freezer.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/kernel/cgroup/freezer.c b/kernel/cgroup/freezer.c
> index e9c15fbe5d9b..d384df2f53c2 100644
> --- a/kernel/cgroup/freezer.c
> +++ b/kernel/cgroup/freezer.c
> @@ -304,6 +304,7 @@ void cgroup_freeze(struct cgroup *cgrp, bool freeze)
>  			 */
>  			if (dsct->freezer.e_freeze > 0)
>  				continue;
> +
>  			WARN_ON_ONCE(dsct->freezer.e_freeze < 0);
>  		}

Hey Umar,

I dug around Github and I think I found the patch you intended to submit
https://github.com/raspberrypi/linux/pull/6632/commits/711f76376ae7e11f48a1c22a4a04828a24d6a87a

Unfortunately, your email only contains the inverse of your PR's
whitespace change removing a line in freezer.c, not the rest of the
patch. Did you perhaps revert that whitespace change in a new commit and
accidentally only submit that commit instead of the whole change?

Thanks,
David Reaver