linux-kernel - Re: [PATCH] ipc: initialize structure memory to zero for shmctl

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Message-ID: <20101007021311.GZ14666@outflux.net>
Date:	Wed, 6 Oct 2010 19:13:11 -0700
From:	Kees Cook <kees.cook@...onical.com>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jiri Slaby <jslaby@...e.cz>,
	"David S. Miller" <davem@...emloft.net>, stable@...nel.org
Subject: Re: [PATCH] ipc: initialize structure memory to zero for shmctl

Hi Al,

On Thu, Oct 07, 2010 at 02:21:36AM +0100, Al Viro wrote:
> On Wed, Oct 06, 2010 at 05:10:31PM -0700, Kees Cook wrote:
> > The old shm interface will leak a few bytes of stack contents. Explicitly
> > initialize the structure to zero-fill the untouched fields.
> 
> Umm...  I wonder if we ever have gaps in there; note that gaps between
> the fields are _not_ initialized in compound literals.  Yes, I realize
> that it's a separate problem, but explicit memset() prior to initializations
> of fields might be a better solution, covering both.

Excellent point. I'll resend with a memset.

-- 
Kees Cook
Ubuntu Security Team
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