From: "Américo Wang" <xiyou.wangcong@gmail.com>
To: walter harms <wharms@bfs.de>
Cc: "Américo Wang" <xiyou.wangcong@gmail.com>,
"Eric Dumazet" <eric.dumazet@gmail.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Vasiliy Kulikov" <segoon@openwall.com>,
"Andreas Dilger" <adilger.kernel@dilger.ca>,
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: Tue, 23 Nov 2010 23:23:55 +0800 [thread overview]
Message-ID: <20101123152355.GB3816@hack> (raw)
In-Reply-To: <4CEBD37E.5060107@bfs.de>
On Tue, Nov 23, 2010 at 03:45:18PM +0100, walter harms wrote:
>Am 23.11.2010 15:01, schrieb Américo Wang:
>> On Mon, Nov 15, 2010 at 08:12:21PM +0100, Eric Dumazet wrote:
>>>
>>> In my understanding, gcc should initialize all holes (and other not
>>> mentioned fields) with 0, even for automatic storage [C99 only mandates
>>> this on static storage]
>>>
>>> I tested on x86_64 and this is the case, but could not find a definitive
>>> answer in gcc documentation.
>>>
>>
>> Yeah, this is not clearly defined by C99 I think, but we can still
>> find some clues in 6.2.6.1, Paragraph 6,
>>
>> "
>> When a value is stored in an object of structure or union type,
>> including in a member object, the bytes of the object representation
>> that correspond to any padding bytes take unspecified values.
>> "
>>
>> So we can't rely on the compiler to initialize the padding bytes
>> too.
>>
>hi all,
>as we see this is not a question of c99.
>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.
>
>People that still want a "undefined" (for what ever reason) can use an option to enable it
>again (e.g. --no-zero-padding).
Well, IMHO, the default behavior should be "undefined", thus
"-fzero-padding" is needed. But, you know, I am not a compiler
people at all. :)
>
>do anyone have a contact so we can forward that request ?
>
gcc@gcc.gnu.org ?
--
Live like a child, think like the god.
next prev parent reply other threads:[~2010-11-23 15:20 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-10 20:38 [PATCH] fs: select: fix information leak to userspace Vasiliy Kulikov
2010-11-12 20:08 ` Andrew Morton
2010-11-13 21:38 ` Andreas Dilger
2010-11-14 9:25 ` [PATCH v2] " Vasiliy Kulikov
2010-11-15 2:06 ` Andrew Morton
2010-11-15 19:12 ` Eric Dumazet
2010-11-16 11:19 ` Boaz Harrosh
2010-11-22 23:50 ` Andrew Morton
2010-11-23 0:20 ` Eric Dumazet
2010-11-23 0:32 ` Andrew Morton
2010-11-23 5:12 ` Dan Carpenter
2010-11-23 6:59 ` Eric Dumazet
2010-11-23 14:01 ` Américo Wang
2010-11-23 14:45 ` walter harms
2010-11-23 15:23 ` Américo Wang [this message]
2010-11-23 18:02 ` Andreas Dilger
2010-11-23 20:18 ` Andrew Morton
2010-11-23 20:22 ` David Miller
2010-11-24 0:24 ` Andreas Dilger
2010-11-24 16:06 ` walter harms
2010-11-24 10:44 ` Pádraig Brady
2010-11-24 11:05 ` Américo Wang
2010-11-24 11:46 ` Pádraig Brady
2010-11-24 12:32 ` Américo Wang
2010-12-15 9:49 ` Al Viro
2010-12-15 20:30 ` Andreas Dilger
2010-12-15 20:33 ` Julia Lawall
2010-12-15 20:52 ` Eric Dumazet
2010-12-15 22:19 ` Andreas Dilger
2010-12-16 9:39 ` Boaz Harrosh
2010-11-24 17:54 ` Valdis.Kletnieks
2010-11-16 18:45 ` Vasiliy Kulikov
2010-11-15 2:05 ` [PATCH] " Andrew Morton
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20101123152355.GB3816@hack \
--to=xiyou.wangcong@gmail.com \
--cc=adilger.kernel@dilger.ca \
--cc=akpm@linux-foundation.org \
--cc=eric.dumazet@gmail.com \
--cc=jakub@redhat.com \
--cc=kernel-janitors@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=segoon@openwall.com \
--cc=viro@zeniv.linux.org.uk \
--cc=wharms@bfs.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).