linux-kernel - Re: [PATCH] softirq: fix memory corruption when freeing tasklet

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

Date: Sat, 27 Jan 2024 08:37:45 -1000
From: Tejun Heo <tj@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mikulas Patocka <mpatocka@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
	dm-devel@...ts.linux.dev, Mike Snitzer <msnitzer@...hat.com>,
	Ignat Korchagin <ignat@...udflare.com>,
	Damien Le Moal <damien.lemoal@....com>,
	Bob Liu <bob.liu@...cle.com>, Hou Tao <houtao1@...wei.com>,
	Nathan Huckleberry <nhuck@...gle.com>,
	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH] softirq: fix memory corruption when freeing
 tasklet_struct

On Fri, Jan 26, 2024 at 01:43:25PM -1000, Tejun Heo wrote:
> Hello,
> 
> The following is a draft patch which implements atomic workqueues and
> convert dm-crypt to use it instead of tasklet. It's an early draft and very
> lightly tested but seems to work more or less. It's on top of wq/for6.9 + a
> pending patchset. The following git branch can be used for testing.
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git wq-atomic-draft
> 
> I'll go over it to make sure all the pieces work. While it adds some
> complications, it doesn't seem too bad and conversion from tasklet should be
> straightforward too.
> 
> - It hooks into tasklet[_hi] for now but if we get to update all of tasklet
>   users, we can just repurpose the tasklet softirq slots directly.
> 
> - I thought about allowing busy-waits for flushes and cancels but it didn't
>   seem necessary. Keeping them blocking has the benefit of avoiding possible
>   nasty deadlocks. We can revisit if there's need.
> 
> - Compared to tasklet, each work item goes through a bit more management
>   code because I wanted to keep the code as unified as possible to regular
>   threaded workqueues. That said, it's not a huge amount and my bet is that
>   the difference is unlikely to be noticeable.

Should have known when it worked too well on the first try but I missed a
part in init and this was just running them on per-cpu workqueues. Will post
an actually working version later.

Thanks.

-- 
tejun