linux-kernel - Re: [PATCH 0/8] make vfork killable/restartable/traceable

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]

Message-ID: <CA+55aFy83CAZ+AVZNtYZc=NnOzaxsQxksuspqBHGVwLx4hvMCg@mail.gmail.com>
Date:	Wed, 27 Jul 2011 12:39:00 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Roland McGrath <roland@...k.frob.com>, Tejun Heo <tj@...nel.org>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Matt Fleming <matt.fleming@...ux.intel.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/8] make vfork killable/restartable/traceable

On Wed, Jul 27, 2011 at 9:31 AM, Oleg Nesterov <oleg@...hat.com> wrote:
>
> CLONE_VFORK sleeps in TASK_INTERRUPTIBLE until the child exits/execs.
> This is obviously not good, it is sooo simple to create the task which
> doesn't react to SIGKILL/SIGSTOP.

Well, I don't know how bad that is. You just kill the child instead.
That's how vfork has always worked, not just on Linux.

And quite frankly, I think your patches 1-3 are unbelievably ugly. If
it was some simple and straightforward "use
wait_for_completion_killable() instead", I wouldn't mind it. But I
think you made a simple and clean sequence convoluted and annoying.

I *suspect* that the killable() thing could be done more nicely by
moving the vfork_completion into the parent instead, and maybe the
vfork cleanup could just use
"complete(&task->parent->vfork_completion);" instead (so if the parent
goes away, it completes some irrelevant init case instead).

So *if* this can be done while still having straightforward code, I
think it might be worth doing. But patches 1-3 just make me go "not
worth the ugliness, especially since it's not a real problem".

                               Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/