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Subject: Re: Potential security problem in patch: Fix reading
	/proc/<pid>/mem when parent dies.
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Date: Fri, 19 Nov 2004 00:00:59 +0000
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On Gwe, 2004-11-19 at 00:52, Linus Torvalds wrote:
> How could we send random signals? That's what the "exit_signal" thing is 
> for, and the code does
> 
> 	if (p->exit_signal != -1)
> 		p->exit_signal = SIGCHLD;
> 
> for that.
> 
> Is there any other way to set exit_signal afterwards? If so, I think we 
> should have a security check at _that_ point.

Ok that makes sense now I look harder at it. While it was added to
protect agains that case the code you quote already covers all the cases
I can see. We can clone new threads but they too will get reparented or
will simply kill us.