linux-kernel - Re: [PATCH 10/16] ptrace: clean transitions between TASK

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:	Wed, 22 Dec 2010 17:00:16 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	roland@...hat.com, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	rjw@...k.pl, jan.kratochvil@...hat.com
Subject: Re: [PATCH 10/16] ptrace: clean transitions between TASK_STOPPED
	and TRACED

On 12/22, Tejun Heo wrote:
>
> On Wed, Dec 22, 2010 at 12:39:48PM +0100, Oleg Nesterov wrote:
> >
> > sys_ptrace() only works for the single thread who did PTRACE_ATTACH,
> > but do_wait() should work for its sub-threads.
> >
> > 	1. the tracer knows that the tracee is stopped
> >
> > 	2. the tracer does ptrace(ATTACH)
> >
> > 	3. the tracer's sub-thread does do_wait()
> >
> > Note! Personally I think we can ignore this "problem", I do not
> > think it can break anything except some specialized test-case.
>
> But if ptrace(ATTACH) doesn't return until the transition is complete
> when the task is already stopped, the tracer's sub-thread's do_wait()
> will behave exactly the same.  The only difference would be that
> ptrace(ATTACH) may now block and/or is failed by a signal delivery.
>
> How would #3 behave differently if STOPPED -> TRACED transition is
> guaranteed to be complete by the end of #2?

Ahhh, sorry. I meant, two threads can do 2. and 3. at the same time.

But let me repeat, it is not that I think we should worry. I mentioned
this only because I think it is better to discuss everything we can,
even the really minor things.

Oleg.

--
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/