From: Pavel Machek <pavel@ucw.cz>
To: Jan Beulich <JBeulich@novell.com>
Cc: mingo@elte.hu, tglx@linutronix.de, hpa@zytor.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86-64: don't leak kernel register values to 32-bit processes
Date: Wed, 7 Oct 2009 11:44:19 +0200 [thread overview]
Message-ID: <20091007094248.GA1425@ucw.cz> (raw)
In-Reply-To: <4AC34D73020000780001744A@vpn.id2.novell.com>
Hi!
> While 32-bit processes can't directly access R8...R15, they can gain
> access to these registers by temporarily switching themselves into
> 64-bit mode. Therefore, registers not preserved anyway by called C
> functions (i.e. R8...R11) must be cleared prior to returning to user
> mode.
How can userspace "temporarily switch itself" to 64bit mode?
Such ability would lead to very interesting behaviour on 32-bit
kernel, I'd say...
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2009-10-08 11:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-30 10:22 [PATCH] x86-64: don't leak kernel register values to 32-bit processes Jan Beulich
2009-10-01 9:59 ` [tip:x86/urgent] x86: Don't leak 64-bit " tip-bot for Jan Beulich
2009-10-07 9:44 ` Pavel Machek [this message]
2009-10-08 11:41 ` [PATCH] x86-64: don't leak " Jan Beulich
2009-10-10 13:27 ` Pavel Machek
2009-10-08 18:58 ` H. Peter Anvin
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