From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752854AbdEJMfE (ORCPT ); Wed, 10 May 2017 08:35:04 -0400 Received: from mga03.intel.com ([134.134.136.65]:16016 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751901AbdEJMfD (ORCPT ); Wed, 10 May 2017 08:35:03 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.38,319,1491289200"; d="scan'208";a="85694762" Date: Wed, 10 May 2017 15:34:58 +0300 From: Jarkko Sakkinen To: Jason Gunthorpe Cc: tpmdd-devel@lists.sourceforge.net, linux-security-module@vger.kernel.org, Peter Huewe , Marcel Selhorst , open list Subject: Re: [PATCH] tpm: fix byte order related arithmetic inconsistency in tpm_getcap() Message-ID: <20170510123458.fh3ef3c55y2wiu35@intel.com> References: <20170507175002.9558-1-jarkko.sakkinen@linux.intel.com> <20170509141353.klo7lilef4qiqfoc@intel.com> <20170509151308.GA13586@obsidianresearch.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170509151308.GA13586@obsidianresearch.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 09, 2017 at 09:13:08AM -0600, Jason Gunthorpe wrote: > On Tue, May 09, 2017 at 05:13:53PM +0300, Jarkko Sakkinen wrote: > > On Sun, May 07, 2017 at 08:50:02PM +0300, Jarkko Sakkinen wrote: > > > You should not do arithmetic with __be32 or __le32 types because > > > sometimes it results incorrect results. Calculations must be done only > > > with integers that are in in the CPU byte order. This commit migrates > > > tpm_getcap() to struct tpm_buf in order to sort out these issues. > > > > > > Signed-off-by: Jarkko Sakkinen > > > Now this should work as Robertos patches move byte order conversion > > > where it should be. Sadly I'm out of reach to my Dell E6400 laptop > > > that I use for TPM 1.2 testing. > > > drivers/char/tpm/tpm-interface.c | 30 ++++++++++++++++-------------- > > > drivers/char/tpm/tpm.h | 13 ------------- > > > 2 files changed, 16 insertions(+), 27 deletions(-) > > > > I've now tested this with TPM 1.2. Any complains? > > Seems reasonable, but which linke had the problematic arithmetic? > > Jason Arithmetic should work but it's not a good practice to do additions, substractions or multiplications in any other byte order than the CPU byte order. sparse also complains about this. /Jarkko