From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758814Ab3IBJDa (ORCPT ); Mon, 2 Sep 2013 05:03:30 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:37819 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758498Ab3IBIzd (ORCPT ); Mon, 2 Sep 2013 04:55:33 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Nicolas Pitre , Russell King , Luis Henriques Subject: [PATCH 41/58] ARM: 7816/1: CONFIG_KUSER_HELPERS: fix help text Date: Mon, 2 Sep 2013 09:54:26 +0100 Message-Id: <1378112083-9475-42-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1378112083-9475-1-git-send-email-luis.henriques@canonical.com> References: <1378112083-9475-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.5.7.21 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicolas Pitre commit ac124504ecf6b20a2457d873d0728a8b991a5b0c upstream. Commit f6f91b0d9fd9 ("ARM: allow kuser helpers to be removed from the vector page") introduced some help text for the CONFIG_KUSER_HELPERS option which is rather contradictory. Let's fix that, and improve it a little. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King Signed-off-by: Luis Henriques --- arch/arm/mm/Kconfig | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index 8d194df..6c5a533 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -768,15 +768,18 @@ config KUSER_HELPERS the CPU type fitted to the system. This permits binaries to be run on ARMv4 through to ARMv7 without modification. + See Documentation/arm/kernel_user_helpers.txt for details. + However, the fixed address nature of these helpers can be used by ROP (return orientated programming) authors when creating exploits. If all of the binaries and libraries which run on your platform are built specifically for your platform, and make no use of - these helpers, then you can turn this option off. However, - when such an binary or library is run, it will receive a SIGILL - signal, which will terminate the program. + these helpers, then you can turn this option off to hinder + such exploits. However, in that case, if a binary or library + relying on those helpers is run, it will receive a SIGILL signal, + which will terminate the program. Say N here only if you are absolutely certain that you do not need these helpers; otherwise, the safe option is to say Y. -- 1.8.3.2