From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CBD3EC10F11 for ; Wed, 10 Apr 2019 21:18:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 99C642082A for ; Wed, 10 Apr 2019 21:18:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726623AbfDJVS5 (ORCPT ); Wed, 10 Apr 2019 17:18:57 -0400 Received: from mga17.intel.com ([192.55.52.151]:50546 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726022AbfDJVS4 (ORCPT ); Wed, 10 Apr 2019 17:18:56 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Apr 2019 14:18:56 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,334,1549958400"; d="scan'208";a="290458712" Received: from jacob-builder.jf.intel.com (HELO jacob-builder) ([10.7.199.155]) by orsmga004.jf.intel.com with ESMTP; 10 Apr 2019 14:18:55 -0700 Date: Wed, 10 Apr 2019 14:21:31 -0700 From: Jacob Pan To: Andriy Shevchenko Cc: iommu@lists.linux-foundation.org, LKML , Joerg Roedel , David Woodhouse , Alex Williamson , Jean-Philippe Brucker , Yi Liu , "Tian, Kevin" , Raj Ashok , Christoph Hellwig , Lu Baolu , "Liu, Yi L" , Liu@smile.fi.intel.com, Eric Auger , jacob.jun.pan@linux.intel.com Subject: Re: [PATCH 08/18] iommu: Introduce cache_invalidate API Message-ID: <20190410142131.50ee2e44@jacob-builder> In-Reply-To: <20190409173755.GX9224@smile.fi.intel.com> References: <1554767973-30125-1-git-send-email-jacob.jun.pan@linux.intel.com> <1554767973-30125-9-git-send-email-jacob.jun.pan@linux.intel.com> <20190409100718.GE9224@smile.fi.intel.com> <20190409094328.03731c3c@jacob-builder> <20190409173755.GX9224@smile.fi.intel.com> Organization: OTC X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 9 Apr 2019 20:37:55 +0300 Andriy Shevchenko wrote: > On Tue, Apr 09, 2019 at 09:43:28AM -0700, Jacob Pan wrote: > > On Tue, 9 Apr 2019 13:07:18 +0300 > > Andriy Shevchenko wrote: > > > On Mon, Apr 08, 2019 at 04:59:23PM -0700, Jacob Pan wrote: > > > > > +int iommu_cache_invalidate(struct iommu_domain *domain, struct > > > > device *dev, > > > > + struct iommu_cache_invalidate_info > > > > *inv_info) +{ > > > > + int ret = 0; > > > > > > Redundant assignment. > > > > > I am not a security expert but initialization of local variable can > > be more secure. > > I was looking at this talk. > > https://outflux.net/slides/2018/lss/danger.pdf > > https://cwe.mitre.org/data/definitions/457.html > > I hardly see any of these applied to your case here. > Care to show what I'm missing? > I thought your comments was that I should not need to initialize local variable ret = 0. Always initialize local variable can be a good security practice as suggested in the paper. Perhaps I missed something :) > > > > + if (unlikely(!domain->ops->cache_invalidate)) > > > > + return -ENODEV; > > > > + > > > > + ret = domain->ops->cache_invalidate(domain, dev, > > > > inv_info); + > > > > + return ret; > > > > +} > [Jacob Pan]