From: "H. Peter Anvin" <hpa@zytor.com>
To: linux-kernel@vger.kernel.org
Subject: Re: SSE related security hole
Date: 18 Apr 2002 14:06:36 -0700 [thread overview]
Message-ID: <a9ncgs$2s2$1@cesium.transmeta.com> (raw)
In-Reply-To: <20020418183639.20946.qmail@science.horizon.com>
Followup to: <20020418183639.20946.qmail@science.horizon.com>
By author: linux@horizon.com
In newsgroup: linux.dev.kernel
>
> Um, people here seem to be assuming that, in the absence of MMX,
> fninit *doesn't* leak information.
>
> I thought it was well-known to just clear (set to all-ones) the
> tag register and not alter the actual floating-point registers.
>
> Thus, it seems quite feasible to reset the tag word with FLDENV and
> store out the FPU registers, even on an 80387.
>
> Isn't this the same security hole? Shouldn't there be 8 FLDZ instructions
> (or equivalent) in the processor state initialization?
>
Perhaps the right thing to do is to have a description in data of the
desired initialization state and just F[NX]RSTOR it?
-hpa
--
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt <amsp@zytor.com>
next prev parent reply other threads:[~2002-04-18 21:07 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-04-18 18:36 SSE related security hole linux
2002-04-18 18:53 ` Richard B. Johnson
2002-04-21 19:52 ` Pavel Machek
2002-04-21 22:11 ` David Wagner
2002-04-18 21:06 ` H. Peter Anvin [this message]
-- strict thread matches above, loose matches on Subject: below --
2002-04-22 22:24 Saxena, Sunil
[not found] <20020418183639.20946.qmail@science.horizon.com.suse.lists.linux.kernel>
[not found] ` <a9ncgs$2s2$1@cesium.transmeta.com.suse.lists.linux.kernel>
2002-04-19 14:06 ` Andi Kleen
2002-04-19 18:00 ` Doug Ledford
2002-04-19 21:04 ` Andrea Arcangeli
2002-04-19 21:35 ` H. Peter Anvin
2002-04-19 21:42 ` Andi Kleen
2002-04-20 3:23 ` Andrea Arcangeli
2002-04-19 22:18 ` Jan Hubicka
[not found] <200204182320.53095.nahshon@actcom.co.il>
2002-04-19 11:22 ` Alan Cox
2002-04-17 23:42 Doug Ledford
2002-04-18 5:26 ` Andrea Arcangeli
2002-04-18 9:10 ` Arjan van de Ven
2002-04-18 11:18 ` Alan Cox
2002-04-18 11:14 ` Andi Kleen
2002-04-18 11:53 ` Alan Cox
2002-04-18 11:46 ` Andi Kleen
2002-04-18 11:55 ` Andi Kleen
2002-04-18 13:44 ` Doug Ledford
2002-04-18 19:20 ` Pavel Machek
2002-04-18 19:32 ` Doug Ledford
2002-04-21 19:54 ` Pavel Machek
2002-04-18 8:22 ` Andi Kleen
2002-04-17 14:51 Jan Hubicka
2002-04-17 15:23 ` Jan Hubicka
2002-04-18 14:57 ` Denis Vlasenko
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