[PATCH 5/5] net: Block MSG_CMSG_COMPAT in send(m)msg and recv(m)msg

[David Miller]

From: Eric Dumazet <eric.dumazet at gmail.com>
Date: Wed, 05 Jun 2013 21:35:25 -0700

> On Thu, 2013-06-06 at 12:56 +1000, Michael Neuling wrote:
>> On Thu, May 23, 2013 at 7:07 AM, Andy Lutomirski <luto at amacapital.net> wrote:
>> > MSG_CMSG_COMPAT is (AFAIK) not intended to be part of the API --
>> > it's a hack that steals a bit to indicate to other networking code
>> > that a compat entry was used.  So don't allow it from a non-compat
>> > syscall.
>> 
>> Dave & Linus
>> 
>> This is causing a regression on 64bit powerpc with 32bit usermode.
>> When I hit userspace, udev is broken and I suspect all networking is
>> broken as well.
>> 
>> Can we please revert 1be374a0518a288147c6a7398792583200a67261 upstream?
>> 
> 
> It seems to also break x86_64, if using 32bit usermode.

Sorry, I only merged this because Ingo Molnar and others kept beating
me over the head about merging this fix.

Linus please revert, and I will not bow to such pressure in the future,
I should know better.