From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Linux-Arch <linux-arch@vger.kernel.org>,
kernel-hardening@lists.openwall.com,
Peter Zijlstra <peterz@infradead.org>,
Jonathan Corbet <corbet@lwn.net>,
Will Deacon <will.deacon@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
"torvalds@linux-foundation.org" <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Alan Cox <alan@linux.intel.com>
Subject: [kernel-hardening] Re: [PATCH v2 01/19] Documentation: document array_ptr
Date: Fri, 12 Jan 2018 11:38:58 +0100 [thread overview]
Message-ID: <CAMuHMdXXB0GxbzV2YR9yvp=DhgXnbm2QRFQzQ+tJ46dG9feC-w@mail.gmail.com> (raw)
In-Reply-To: <151571799008.27429.12325141216769795517.stgit@dwillia2-desk3.amr.corp.intel.com>
Hi Dan,
On Fri, Jan 12, 2018 at 1:46 AM, Dan Williams <dan.j.williams@intel.com> wrote:
> From: Mark Rutland <mark.rutland@arm.com>
>
> Document the rationale and usage of the new array_ptr() helper.
>
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Signed-off-by: Will Deacon <will.deacon@arm.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Thanks for the update!
> --- /dev/null
> +++ b/Documentation/speculation.txt
> @@ -0,0 +1,142 @@
> +This document explains potential effects of speculation, and how undesirable
> +effects can be mitigated portably using common APIs.
> +
> +===========
> +Speculation
> +===========
> +
> +To improve performance and minimize average latencies, many contemporary CPUs
> +employ speculative execution techniques such as branch prediction, performing
> +work which may be discarded at a later stage.
> +
> +Typically speculative execution cannot be observed from architectural state,
> +such as the contents of registers. However, in some cases it is possible to
> +observe its impact on microarchitectural state, such as the presence or
> +absence of data in caches. Such state may form side-channels which can be
> +observed to extract secret information.
> +
> +For example, in the presence of branch prediction, it is possible for bounds
> +checks to be ignored by code which is speculatively executed. Consider the
> +following code:
> +
> + int load_array(int *array, unsigned int idx) {
One more opening curly brace to move to the next line.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2018-01-12 10:38 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-12 0:46 [kernel-hardening] [PATCH v2 00/19] prevent bounds-check bypass via speculative execution Dan Williams
2018-01-12 0:46 ` [kernel-hardening] [PATCH v2 01/19] Documentation: document array_ptr Dan Williams
2018-01-12 10:38 ` Geert Uytterhoeven [this message]
2018-01-16 21:01 ` [kernel-hardening] " Kees Cook
2018-01-12 0:46 ` [kernel-hardening] [PATCH v2 02/19] arm64: implement ifence_array_ptr() Dan Williams
2018-01-12 0:46 ` [kernel-hardening] [PATCH v2 03/19] arm: " Dan Williams
2018-01-12 0:46 ` [kernel-hardening] [PATCH v2 04/19] x86: implement ifence() Dan Williams
2018-01-12 2:27 ` [kernel-hardening] " Eric W. Biederman
2018-01-12 3:39 ` Dan Williams
2018-01-12 0:46 ` [kernel-hardening] [PATCH v2 05/19] x86: implement ifence_array_ptr() and array_ptr_mask() Dan Williams
2018-01-12 0:46 ` [kernel-hardening] [PATCH v2 06/19] asm-generic/barrier: mask speculative execution flows Dan Williams
2018-01-12 2:42 ` [kernel-hardening] " Eric W. Biederman
2018-01-12 9:12 ` Peter Zijlstra
2018-01-13 0:41 ` Dan Williams
2018-01-15 8:46 ` Peter Zijlstra
2018-01-12 0:47 ` [kernel-hardening] [PATCH v2 07/19] x86: introduce __uaccess_begin_nospec and ASM_IFENCE Dan Williams
2018-01-12 17:51 ` [kernel-hardening] " Josh Poimboeuf
2018-01-12 18:21 ` Dan Williams
2018-01-12 18:58 ` Josh Poimboeuf
2018-01-12 19:26 ` Dan Williams
2018-01-12 20:01 ` Linus Torvalds
2018-01-12 20:41 ` Josh Poimboeuf
2018-01-12 0:47 ` [kernel-hardening] [PATCH v2 08/19] x86: use __uaccess_begin_nospec and ASM_IFENCE in get_user paths Dan Williams
2018-01-12 1:11 ` [kernel-hardening] " Linus Torvalds
2018-01-12 1:14 ` Dan Williams
2018-01-12 0:47 ` [kernel-hardening] [PATCH v2 09/19] ipv6: prevent bounds-check bypass via speculative execution Dan Williams
2018-01-12 0:47 ` [kernel-hardening] [PATCH v2 10/19] ipv4: " Dan Williams
2018-01-12 7:59 ` [kernel-hardening] " Greg KH
2018-01-12 18:47 ` Dan Williams
2018-01-13 8:56 ` Greg KH
2018-01-12 0:47 ` [kernel-hardening] [PATCH v2 11/19] vfs, fdtable: " Dan Williams
2018-01-12 0:47 ` [kernel-hardening] [PATCH v2 12/19] userns: " Dan Williams
2018-01-12 0:47 ` [kernel-hardening] [PATCH v2 13/19] udf: " Dan Williams
2018-01-15 10:32 ` [kernel-hardening] " Jan Kara
2018-01-15 17:49 ` Dan Williams
2018-01-12 0:47 ` [kernel-hardening] [PATCH v2 14/19] [media] uvcvideo: " Dan Williams
2018-08-06 21:40 ` Laurent Pinchart
2018-01-12 0:47 ` [kernel-hardening] [PATCH v2 15/19] carl9170: " Dan Williams
2018-01-12 14:42 ` [kernel-hardening] " Christian Lamparter
2018-01-12 18:39 ` Dan Williams
2018-01-12 20:01 ` Christian Lamparter
2018-01-12 23:05 ` Dan Williams
2018-01-12 0:47 ` [kernel-hardening] [PATCH v2 16/19] p54: " Dan Williams
2018-01-12 0:47 ` [kernel-hardening] [PATCH v2 17/19] qla2xxx: " Dan Williams
2018-01-12 1:19 ` [kernel-hardening] " James Bottomley
2018-01-12 5:38 ` Dan Williams
2018-01-12 6:05 ` James Bottomley
2018-01-12 0:48 ` [kernel-hardening] [PATCH v2 18/19] cw1200: " Dan Williams
2018-01-12 0:48 ` [kernel-hardening] [PATCH v2 19/19] net: mpls: " Dan Williams
2018-01-12 1:19 ` [kernel-hardening] Re: [PATCH v2 00/19] " Linus Torvalds
2018-01-12 1:41 ` Dan Williams
2018-01-18 13:18 ` Will Deacon
2018-01-18 16:58 ` Dan Williams
2018-01-18 17:05 ` Will Deacon
2018-01-18 21:41 ` Laurent Pinchart
2018-01-13 0:15 ` Tony Luck
2018-01-13 18:51 ` Linus Torvalds
2018-01-16 19:21 ` Tony Luck
2018-01-12 10:02 ` Russell King - ARM Linux
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