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Message-Id: <20071119171455.c05793a0.dada1@cosmosbay.com>
Date: Mon, 19 Nov 2007 17:14:55 +0100
From: Eric Dumazet <dada1@...mosbay.com>
To: Ulrich Drepper <drepper@...hat.com>
Cc: linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
mingo@...e.hu, tglx@...utronix.de, torvalds@...ux-foundation.org
Subject: Re: [PATCHv3 0/4] sys_indirect system call
On Mon, 19 Nov 2007 07:48:23 -0800
Ulrich Drepper <drepper@...hat.com> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Eric Dumazet wrote:
> > So when you recompile your old program (as you post it and as I commented on),
> > it will pass a >= 12 bytes data to kernel, with only first 4 bytes set to O_CLOEXEC.
> >
> > Other bytes will contain junk
>
> If you don't initialize the entire structure and you use it all, of
> course you get undefined behavior. That's nothing new. The program I
> attached is not an example, it's a test for the functionality in this patch.
>
> Like with every kernel interface, you have to use it correctly. The
> good news is that user programs should never use this syscall directly
> (just like don't for existing ones).
>
> I see no problem at all here.
I do see a problem, because some readers will take your example as a reference,
as it will probably sit in a page that google^Wsearch_engines will bring at the
top of search results for next ten years or so.
(I bet for "sys_indirect syscall" -> http://lwn.net/Articles/258708/ )
Next time you post it, please warn users that it will break in some years, or
state clearly this should only be used internally by glibc.
Thank you
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