Re: [PATCH v2] fs: select: fix information leak to userspace

From: walter harms <wharms@bfs.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Andreas Dilger" <adilger.kernel@dilger.ca>,
	"Américo Wang" <xiyou.wangcong@gmail.com>,
	"Eric Dumazet" <eric.dumazet@gmail.com>,
	"Vasiliy Kulikov" <segoon@openwall.com>,
	kernel-janitors@vger.kernel.org,
	"Alexander Viro" <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Jakub Jelinek" <jakub@redhat.com>
Subject: Re: [PATCH v2] fs: select: fix information leak to userspace
Date: Wed, 24 Nov 2010 17:06:50 +0100	[thread overview]
Message-ID: <4CED381A.5060100@bfs.de> (raw)
In-Reply-To: <20101123121840.e9d17d91.akpm@linux-foundation.org>


Am 23.11.2010 21:18, schrieb Andrew Morton:
> On Tue, 23 Nov 2010 11:02:44 -0700
> Andreas Dilger <adilger.kernel@dilger.ca> wrote:
> 
>> On 2010-11-23, at 07:45, walter harms wrote:
>>> Maybe we can convince the gcc people to make 0 padding default. That will not solve the problems for other compilers but when they claim "works like gcc" we can press then to support this also. I can imagine that this will close some other subtle leaks also.
>>
>> It makes the most sense to tackle this at the GCC level, since the added overhead of doing memset(0) on the whole struct may be non-trivial for commonly-used and/or large structures.
> 
> (My, what long lines you have!)
> 
> We can't reasonably address this with gcc changes.  If gcc starts doing
> what we want in the next release, how long will it be until that
> release is the *oldest* version of gcc which the kernel may be compiled
> with?  Five years?
> 
> 
agreed, but it does not mean not to talk to the gcc people that there is
an interesse to change.

re,
 wh