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Date: Sun, 10 Mar 2002 21:37:06 +0100
From: Andreas Ferber <aferber@techfak.uni-bielefeld.de>
To: linux-kernel@vger.kernel.org
Cc: Danek Duvall <duvall@emufarm.org>, Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: root-owned /proc/pid files for threaded apps?
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In-Reply-To: <20020309030937.GA244@lorien.emufarm.org>; from duvall@emufarm.org on Fri, Mar 08, 2002 at 07:09:37PM -0800
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On Fri, Mar 08, 2002 at 07:09:37PM -0800, Danek Duvall wrote:

> Ok, after trying all four combinations (call to wmb() moved or not, and
> set_user(0, 1) vs set_user(0, 0)), it turns out all four exhibit
> skipping, so that's unrelated (in fact, it seems to happen not on net
> access, but on redraw -- mozilla's dialogs make xmms skip, too).

OK, so it's clearly unrelated.

> I'll leave it for someone else to decide what arguments to set_user()
> exec_usermodehelper() should pass.

Clearing dumpable at this point is obviously wrong as it always has
side-effects on the process that was leading into the module request.

It's also unnecessary, as it /only/ has effect on the /old/ mm_struct,
before doing the execve() of the usermode helper. As request_module
and friends don't introduce sensitive data into the address space of
the calling process, leaving dumpable alone is just fine.

So, IMO, set_user(0, 0) should be the way to go.

Andreas
-- 
       Andreas Ferber - dev/consulting GmbH - Bielefeld, FRG
     ---------------------------------------------------------
         +49 521 1365800 - af@devcon.net - www.devcon.net
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