linux-kernel - Re: compat: autofs v5 packet size ambiguity

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Message-ID: <4F453208.7040902@zytor.com>
Date:	Wed, 22 Feb 2012 10:20:56 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Ian Kent <raven@...maw.net>, David Miller <davem@...emloft.net>,
	linux-kernel@...r.kernel.org, autofs@...r.kernel.org,
	Thomas Meyer <thomas@...3r.de>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: compat: autofs v5 packet size ambiguity - update

On 02/22/2012 10:16 AM, Linus Torvalds wrote:
>
> Because that padding word for size is just random data.
> 
> In fact, we probably should clear it. I suspect we leak kernel stack
> contents to autofs. Not that it matters (system daemon with root
> privileges and all that), but it's another case of the whole "packing
> data structures" issue.
> 

Fortunately this is not true -- there is a memset(0) of the entire
packet before the packet is built in kernel space.  Otherwise we'd have
a security hole.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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