linux-kernel - Re: [PATCH] kill an obsolete sub-thread-ptrace stuff

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Message-ID: <20070803220048.GA277@tv-sign.ru>
Date:	Sat, 4 Aug 2007 02:00:48 +0400
From:	Oleg Nesterov <oleg@...sign.ru>
To:	Roland McGrath <roland@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kill an obsolete sub-thread-ptrace stuff

On 08/03, Roland McGrath wrote:
>
> > There is a couple of subtle checks which were needed to handle ptracing from
> > the same thread group. This was deprecated a long ago, imho this code just
> > complicates the understanding.
> 
> Looks ok to me.

Thanks!

> > And, the "->parent->signal->flags & SIGNAL_GROUP_EXIT" check in exit_notify()
> > is not right. SIGNAL_GROUP_EXIT can mean exec(), not exit_group(). This means
> > ptracer can lose a ptraced zombie on exec(). Minor problem, but still the bug.
> 
> This bug never happens because this check is only in the now-impossible
> ptrace-same-group case.

This means that changelog is wrong and should be changed.

However, I disagree. exit_notify() doesn't check the ptrace-same-group case. So,
unless I missed something, we set EXIT_DEAD in any case, even if ptracer doesn't
belong to our thread group.

No?

Oleg.

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