Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755531Ab3H2GCD (ORCPT ); Thu, 29 Aug 2013 02:02:03 -0400 Received: from smtp-fw-33001.amazon.com ([207.171.189.228]:59210 "EHLO smtp-fw-33001.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753032Ab3H2GCB (ORCPT ); Thu, 29 Aug 2013 02:02:01 -0400 X-IronPort-AV: E=Sophos;i="4.89,981,1367971200"; d="scan'208";a="607704476" Date: Wed, 28 Aug 2013 23:01:53 -0700 From: Matt Wilson To: Prarit Bhargava CC: , Clemens Ladisch Subject: Re: [PATCH] hpet, allow user controlled mmap for user processes Message-ID: <20130829060151.GA7439@u109add4315675089e695.ant.amazon.com> References: <51487B59.6010607@ladisch.de> <1363959174-28999-1-git-send-email-prarit@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <1363959174-28999-1-git-send-email-prarit@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1698 Lines: 36 On Fri, Mar 22, 2013 at 09:32:54AM -0400, Prarit Bhargava wrote: > The CONFIG_HPET_MMAP Kconfig option exposes the memory map of the HPET > registers to userspace. The Kconfig help points out that in some cases this > can be a security risk as some systems may erroneously configure the map such > that additional data is exposed to userspace. > > This is a problem for distributions -- some users want the MMAP functionality > but it comes with a significant security risk. In an effort to mitigate this > risk, and due to the low number of users of the MMAP functionality, I've > introduced a kernel parameter, hpet_mmap_enable, that is required in order > to actually have the HPET MMAP exposed. > > [v2]: Clemens suggested modifying the Kconfig help text and making the > default setting configurable. > [v3]: Fixed up Documentation and Kconfig entries, default now "Y" > [v4]: After testing, found that I need to modify CONFIG_HPET_MMAP_DEFAULT usage > > Signed-off-by: Prarit Bhargava > Cc: Clemens Ladisch > --- > Documentation/kernel-parameters.txt | 4 ++++ > drivers/char/Kconfig | 9 +++++++-- > drivers/char/hpet.c | 25 +++++++++++++++++++++++-- > 3 files changed, 34 insertions(+), 4 deletions(-) It doesn't seem like this patch got picked up and seems like a good idea to me. Clemens, what do you think? Acked-by: Matt Wilson --msw -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/