From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacob Pan Subject: Re: [PATCH 08/18] iommu: Introduce cache_invalidate API Date: Wed, 10 Apr 2019 14:21:31 -0700 Message-ID: <20190410142131.50ee2e44@jacob-builder> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190409173755.GX9224@smile.fi.intel.com> Sender: linux-kernel-owner@vger.kernel.org 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 List-Id: iommu@lists.linux-foundation.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] 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 0EBF9C10F11 for ; Wed, 10 Apr 2019 21:19:16 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D60782082A for ; Wed, 10 Apr 2019 21:19:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D60782082A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id A1036191D; Wed, 10 Apr 2019 21:19:15 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 8481E1E40 for ; Wed, 10 Apr 2019 21:18:57 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id F065C174 for ; Wed, 10 Apr 2019 21:18:56 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga105.jf.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 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 Cc: "Liu, Yi L" , "Tian, Kevin" , Raj Ashok , Jean-Philippe Brucker , iommu@lists.linux-foundation.org, LKML , Alex Williamson , Liu@smile.fi.intel.com, David Woodhouse X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org Message-ID: <20190410212131.E9dR7KW5efQAeB0SHDtuaAG2A85YLKrkwZqr74M6ifE@z> 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] _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu