linux-kernel - Re: [PATCH 1/1] ptrace: __ptrace_detach: do __wake_up

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]

Date:	Thu, 2 Jul 2009 20:51:39 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Roland McGrath <roland@...hat.com>,
	Vitaly Mayatskikh <vmayatsk@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] ptrace: __ptrace_detach: do __wake_up_parent() if
	we reap the tracee

On 07/01, Oleg Nesterov wrote:
>
> --- WAIT/kernel/ptrace.c~PT_DETACH_WAKE_PARENT	2009-07-01 19:59:01.000000000 +0200
> +++ WAIT/kernel/ptrace.c	2009-07-01 20:52:58.000000000 +0200
> @@ -266,9 +266,10 @@ static int ignoring_children(struct sigh
>   * or self-reaping.  Do notification now if it would have happened earlier.
>   * If it should reap itself, return true.
>   *
> - * If it's our own child, there is no notification to do.
> - * But if our normal children self-reap, then this child
> - * was prevented by ptrace and we must reap it now.
> + * If it's our own child, there is no notification to do. But if our normal
> + * children self-reap, then this child was prevented by ptrace and we must
> + * reap it now, in that case we must also wake up sub-threads sleeping in
> + * do_wait().
>   */
>  static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
>  {
> @@ -278,8 +279,10 @@ static bool __ptrace_detach(struct task_
>  		if (!task_detached(p) && thread_group_empty(p)) {
>  			if (!same_thread_group(p->real_parent, tracer))
>  				do_notify_parent(p, p->exit_signal);
> -			else if (ignoring_children(tracer->sighand))
> +			else if (ignoring_children(tracer->sighand)) {
> +				__wake_up_parent(p, tracer);
>  				p->exit_signal = -1;
> +			}

I wonder if we need more fixes here.

ignoring_children() is not exactly right afaics, we assume that
tracee->exit_signal == SIGCHLD.

But I guess this can be ignored, it falls into "ptracing with SIGCHLD
ignored asks for trouble" category.

But !same_thread_group() doesn't look 100% right too, for the same
reason. If ->exit_signal != SIGCHLD, we can't assume we already had
the correct notification. Hopefully this can be ignored too.

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/