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From: Roland McGrath <roland@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Andi Kleen <andi@firstfloor.org>,
	David Howells <dhowells@redhat.com>,
	Neil Horman <nhorman@tuxdriver.com>,
	Rusty Russell <rusty@rustcorp.com.au>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] wait_for_helper: SIGCHLD from user-space can lead to use-after-free
Date: Wed, 10 Mar 2010 13:27:10 -0800 (PST)	[thread overview]
Message-ID: <20100310212710.D66A3A7C@magilla.sf.frob.com> (raw)
In-Reply-To: Oleg Nesterov's message of  Wednesday, 10 March 2010 22:19:23 +0100 <20100310211923.GA6485@redhat.com>

> Yes. kthreads run with all signal ignored, this is inherited from
> kthreadd() which does ignore_signal().

Ok.

> I don't think this can work. SIG_DFL for SIGCHLD is OK because it is
> sig_kernel_ignore(). But, say, SIGHUP and other signals still should
> be ignored, otherwise we have the same problems with the unwanted
> signal_pending() this patch tries to avoid.

Yes, I see.

> But even if we could do this,
> 
> > That should make it redundant in ____call_usermodehelper,
> > so it could be removed from there.
> 
> Please note that __call_usermodehelper() forks ____call_usermodehelper() too.

Ok.


Thanks,
Roland

      reply	other threads:[~2010-03-10 21:28 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-10 17:16 Oleg Nesterov
2010-03-10 18:07 ` Neil Horman
2010-03-10 20:32 ` Roland McGrath
2010-03-10 21:19   ` Oleg Nesterov
2010-03-10 21:27     ` Roland McGrath [this message]

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