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From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Mikael Pettersson <mikpe@it.uu.se>, Ingo Molnar <mingo@elte.hu>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] x86: ia32_signal: remove unnecessary padding
Date: Wed, 12 Nov 2008 10:02:40 -0800	[thread overview]
Message-ID: <491B1A40.5020900@ct.jp.nec.com> (raw)
In-Reply-To: <491B0E6F.2010301@zytor.com>

H. Peter Anvin wrote:
> Mikael Pettersson wrote:
>> It does cause each signal delivery to leak 2 uninitialised
>> kernel bytes to the end of retcode[], which seems unnecessary.
> 
> Not just unnecessary, it is a huge no-no for security.

Am I missing important thing?
The frame->retcode is 8 bytes and packed structure with padding
is 10 bytes each, and the code is copied to user stack 8 bytes only.

err |= __copy_to_user(frame->retcode, &code, 8);

I don't think the behavior is changed.

thanks,
Hiroshi Shimamoto

> 
> NAK on this.
> 
> 	-hpa
> --
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  reply	other threads:[~2008-11-12 18:02 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-12  3:09 [PATCH 1/2] x86: signal_32: introduce retcode and rt_retcode Hiroshi Shimamoto
2008-11-12  3:11 ` [PATCH 2/2] x86: ia32_signal: remove unnecessary padding Hiroshi Shimamoto
2008-11-12 11:29   ` Ingo Molnar
2008-11-12 12:33     ` Mikael Pettersson
2008-11-12 17:12       ` H. Peter Anvin
2008-11-12 18:02         ` Hiroshi Shimamoto [this message]
2008-11-12 18:12           ` H. Peter Anvin
2008-11-13  8:45             ` Mikael Pettersson
2008-11-13 17:38               ` H. Peter Anvin
2008-11-12 12:56   ` Andi Kleen
2008-11-12 18:34     ` Hiroshi Shimamoto

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