From: Pavel Machek <pavel@ucw.cz>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andi Kleen <ak@linux.intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"tim.c.chen@linux.intel.com" <tim.c.chen@linux.intel.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"riel@redhat.com" <riel@redhat.com>,
"keescook@google.com" <keescook@google.com>,
"gnomes@lxorguk.ukuu.org.uk" <gnomes@lxorguk.ukuu.org.uk>,
"pjt@google.com" <pjt@google.com>,
"dave.hansen@intel.com" <dave.hansen@intel.com>,
"jikos@kernel.org" <jikos@kernel.org>,
"gregkh@linux-foundation.org" <gregkh@linux-foundation.org>
Subject: Re: [PATCH v6 11/10] x86/retpoline: Avoid return buffer underflows on context switch
Date: Fri, 16 Feb 2018 09:58:00 +0100 [thread overview]
Message-ID: <20180216085800.GA7616@amd> (raw)
In-Reply-To: <1515503060.22302.19.camel@infradead.org>
On Tue 2018-01-09 13:04:20, David Woodhouse wrote:
> On Mon, 2018-01-08 at 19:27 -0800, Andy Lutomirski wrote:
> > >
> > > If SMEP is not active, speculation can go anywhere, including to a user
> > > controlled gadget which can reload any registers it needs, including
> > > with immediate constants.
> >
> > I thought that, even on pre-SMEP hardware, the CPU wouldn't
> > speculatively execute from NX pages. And PTI marks user memory NX
> > in kernel mode.
>
> Hm, now that could be useful.
>
> Do *all* the KPTI backports (some of which are reimplementations rather
> than strictly backports) mark user memory NX?
Hmm. We'd still want to do something on 32-bit, and those might not
even have NX support in hardware.
Pentium 4 (and such) is probably advanced enough to be vulnerable to
spectre, but not new enough to support NX...
Pavel
--
(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:[~2018-02-16 8:58 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-07 22:11 [PATCH v6 00/10] Retpoline: Avoid speculative indirect calls in kernel David Woodhouse
2018-01-07 22:11 ` [PATCH v6 01/10] x86/retpoline: Add initial retpoline support David Woodhouse
2018-01-08 10:45 ` Peter Zijlstra
2018-01-08 10:53 ` David Woodhouse
2018-01-08 11:03 ` Peter Zijlstra
2018-01-08 12:45 ` David Woodhouse
2018-01-08 13:42 ` Josh Poimboeuf
2018-01-08 13:46 ` Thomas Gleixner
2018-01-08 13:53 ` Josh Poimboeuf
2018-01-08 14:26 ` David Woodhouse
2018-01-08 21:20 ` Josh Poimboeuf
2018-01-09 12:36 ` Peter Zijlstra
2018-01-09 13:35 ` Thomas Gleixner
2018-01-09 13:40 ` Woodhouse, David
2018-01-07 22:11 ` [PATCH v6 02/10] x86/retpoline/crypto: Convert crypto assembler indirect jumps David Woodhouse
2018-01-08 13:49 ` Josh Poimboeuf
2018-01-07 22:11 ` [PATCH v6 03/10] x86/retpoline/entry: Convert entry " David Woodhouse
2018-01-07 22:11 ` [PATCH v6 04/10] x86/retpoline/ftrace: Convert ftrace " David Woodhouse
2018-01-07 22:11 ` [PATCH v6 05/10] x86/retpoline/hyperv: Convert " David Woodhouse
2018-01-07 22:11 ` [PATCH v6 06/10] x86/retpoline/xen: Convert Xen hypercall " David Woodhouse
2018-01-07 22:11 ` [PATCH v6 07/10] x86/retpoline/checksum32: Convert assembler " David Woodhouse
2018-01-07 22:11 ` [PATCH v6 08/10] x86/retpoline/irq32: " David Woodhouse
2018-01-07 22:11 ` [PATCH v6 09/10] x86/retpoline: Add boot time option to disable retpoline David Woodhouse
2018-01-07 22:11 ` [PATCH v6 10/10] x86/retpoline: Exclude objtool with retpoline David Woodhouse
2018-01-08 10:25 ` Thomas Gleixner
2018-01-08 10:34 ` Woodhouse, David
2018-01-08 13:20 ` Josh Poimboeuf
2018-01-07 22:22 ` [PATCH v6 00/10] Retpoline: Avoid speculative indirect calls in kernel Linus Torvalds
2018-01-08 10:01 ` Thomas Gleixner
2018-01-08 17:54 ` Ingo Molnar
2018-01-08 21:10 ` Thomas Gleixner
2018-01-08 10:34 ` Paul Turner
2018-01-08 10:38 ` Jiri Kosina
2018-01-08 10:45 ` Paul Turner
2018-01-08 10:42 ` Paul Turner
2018-01-08 11:16 ` Andrew Cooper
2018-01-08 11:25 ` Paul Turner
2018-01-08 16:13 ` Alexei Starovoitov
2018-01-10 15:20 ` Woodhouse, David
2018-01-10 15:31 ` Dr. David Alan Gilbert
2018-01-08 10:45 ` David Woodhouse
2018-01-08 10:53 ` Paul Turner
2018-01-08 12:49 ` David Woodhouse
2018-01-08 23:44 ` [PATCH v6 11/10] x86/retpoline: Avoid return buffer underflows on context switch David Woodhouse
2018-01-08 23:56 ` Linus Torvalds
2018-01-08 23:58 ` Woodhouse, David
2018-01-09 0:35 ` Linus Torvalds
2018-01-09 0:42 ` David Woodhouse
2018-01-09 0:48 ` Linus Torvalds
2018-01-09 0:55 ` David Woodhouse
2018-01-09 0:44 ` Andi Kleen
2018-01-09 0:58 ` Linus Torvalds
2018-01-09 1:15 ` Andrew Cooper
2018-01-09 3:27 ` Andy Lutomirski
2018-01-09 13:04 ` David Woodhouse
2018-01-09 13:10 ` Peter Zijlstra
2018-01-09 17:53 ` Kees Cook
2018-01-09 18:09 ` Linus Torvalds
2018-02-16 8:58 ` Pavel Machek [this message]
2018-01-09 1:16 ` Andi Kleen
2018-01-09 1:21 ` [PATCH v6 11/10] x86/retpoline: Avoid return buffer underflows on context switch II Andi Kleen
2018-01-09 1:23 ` Woodhouse, David
2018-01-09 1:49 ` Andi Kleen
2018-01-09 1:53 ` Paul Turner
2018-01-09 1:18 ` [PATCH v6 11/10] x86/retpoline: Avoid return buffer underflows on context switch Woodhouse, David
2018-01-09 0:06 ` Andi Kleen
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