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From: Andi Kleen <andi@firstfloor•org>
To: David Miller <davem@davemloft•net>
Cc: sar@nec-labs•com, luto@amacapital•net, netdev@vger•kernel.org,
	mtk.manpages@gmail•com, ebiederm@xmission•com
Subject: Re: bug in passing file descriptors
Date: Mon, 07 Oct 2013 15:55:02 -0700	[thread overview]
Message-ID: <87li24zo6x.fsf@tassilo.jf.intel.com> (raw)
In-Reply-To: <20131007.173237.1669132001431607341.davem@davemloft.net> (David Miller's message of "Mon, 07 Oct 2013 17:32:37 -0400 (EDT)")

David Miller <davem@davemloft•net> writes:

> From: Steve Rago <sar@nec-labs•com>
> Date: Mon, 7 Oct 2013 16:29:15 -0400
>
>> On 10/07/2013 03:42 PM, David Miller wrote:
>>> There is no compatability issue.
>>>
>>> 32-bit tasks will always see the 4-byte align/length.
>>> 64-bit tasks will always see the 8-byte align/length.
>>>
>> 
>> Really?  So when I compile my application on a 32-bit Linux box and
>> then try to run it on a 64-bit Linux box, you're not going to overrun
>> my buffer when CMSG_SPACE led me to allocate an insufficient amount of
>> memory needed to account for padding on the 64-bit platform?
>
> We have a compatability layer that gives 32-bit applications the
> same behavior as if they had run on a 32-bit machine.
>
> Search around for the MSG_MSG_COMPAT flag and how that is used in
> net/socket.c

But it seems the compat layer doesn't handle this correctly,
otherwise Steve's original test case would work.

Must be a bug somewhere in the compat layer.

-Andi

-- 
ak@linux•intel.com -- Speaking for myself only

  reply	other threads:[~2013-10-07 22:55 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-07 18:27 bug in passing file descriptors Steve Rago
2013-10-07 18:44 ` Andy Lutomirski
2013-10-07 19:06   ` Steve Rago
2013-10-07 19:12     ` David Miller
2013-10-07 19:17       ` Steve Rago
2013-10-07 19:42         ` David Miller
2013-10-07 20:29           ` Steve Rago
2013-10-07 21:32             ` David Miller
2013-10-07 22:55               ` Andi Kleen [this message]
2013-10-08 14:32                 ` Steve Rago
2013-10-08 16:02                   ` Andy Lutomirski
2013-10-08 16:18                     ` Steve Rago
2013-10-08 16:41                       ` Andi Kleen
2013-10-08 16:51                         ` Steve Rago
2013-10-09 14:07                           ` Steve Rago
2013-10-08  8:43             ` David Laight

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