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Message-ID: <18715.59672.641830.690773@harpo.it.uu.se>
Date: Thu, 13 Nov 2008 09:45:12 +0100
From: Mikael Pettersson <mikpe@...uu.se>
To: "H. Peter Anvin" <hpa@...or.com>
Cc: Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>,
Mikael Pettersson <mikpe@...uu.se>,
Ingo Molnar <mingo@...e.hu>,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] x86: ia32_signal: remove unnecessary padding
H. Peter Anvin writes:
> Hiroshi Shimamoto wrote:
> > 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.
> >
>
> Ah, nevermind, then. Then it fine, obviously.
Agreed. I wonder how on earth those templates ended
up as 10 bytes large when retcode[] always has been
8 bytes.
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