From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 02/21] arm64/iommu: improve mmap bounds checking Date: Sun, 7 Apr 2019 08:59:23 +0200 Message-ID: <20190407065923.GA9086@lst.de> References: <20190327080448.5500-1-hch@lst.de> <20190327080448.5500-3-hch@lst.de> <3629087c-a8cb-d66e-840b-cfee125bdf4c@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <3629087c-a8cb-d66e-840b-cfee125bdf4c@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: Robin Murphy Cc: Christoph Hellwig , Joerg Roedel , Catalin Marinas , Will Deacon , Tom Lendacky , iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org List-Id: iommu@lists.linux-foundation.org On Fri, Apr 05, 2019 at 06:30:52PM +0100, Robin Murphy wrote: > On 27/03/2019 08:04, Christoph Hellwig wrote: >> The nr_pages checks should be done for all mmap requests, not just those >> using remap_pfn_range. > > Hmm, the logic in iommu_dma_mmap() inherently returns an error for the "off > >= nr_pages" case already. It's also supposed to be robust against the > "vma_pages(vma) > nr_pages - off" condition, although by making the partial > mapping and treating it as a success, rather than doing nothing and > returning an error. What's the exact motivation here? Have one error check at the front of the function that is identical to the mmap checks in the other dma_map_ops instances so that: a) we get the same error behavior for partial requests everywhere b) we can lift these checks into common code in the next round. 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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 69D1AC10F0E for ; Sun, 7 Apr 2019 06:59:38 +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 2B59C20896 for ; Sun, 7 Apr 2019 06:59:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2B59C20896 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de 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 D5CB2ACD; Sun, 7 Apr 2019 06:59:37 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 220B9481 for ; Sun, 7 Apr 2019 06:59:37 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from newverein.lst.de (verein.lst.de [213.95.11.211]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id A914263D for ; Sun, 7 Apr 2019 06:59:36 +0000 (UTC) Received: by newverein.lst.de (Postfix, from userid 2407) id B7D2A67329; Sun, 7 Apr 2019 08:59:23 +0200 (CEST) Date: Sun, 7 Apr 2019 08:59:23 +0200 From: Christoph Hellwig To: Robin Murphy Subject: Re: [PATCH 02/21] arm64/iommu: improve mmap bounds checking Message-ID: <20190407065923.GA9086@lst.de> References: <20190327080448.5500-1-hch@lst.de> <20190327080448.5500-3-hch@lst.de> <3629087c-a8cb-d66e-840b-cfee125bdf4c@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <3629087c-a8cb-d66e-840b-cfee125bdf4c@arm.com> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: Tom Lendacky , Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Christoph Hellwig , linux-arm-kernel@lists.infradead.org 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: <20190407065923.WyTsS05gsHST-8xpTQ6M1DBMSOjOsWTPWSoOnXD8zHY@z> On Fri, Apr 05, 2019 at 06:30:52PM +0100, Robin Murphy wrote: > On 27/03/2019 08:04, Christoph Hellwig wrote: >> The nr_pages checks should be done for all mmap requests, not just those >> using remap_pfn_range. > > Hmm, the logic in iommu_dma_mmap() inherently returns an error for the "off > >= nr_pages" case already. It's also supposed to be robust against the > "vma_pages(vma) > nr_pages - off" condition, although by making the partial > mapping and treating it as a success, rather than doing nothing and > returning an error. What's the exact motivation here? Have one error check at the front of the function that is identical to the mmap checks in the other dma_map_ops instances so that: a) we get the same error behavior for partial requests everywhere b) we can lift these checks into common code in the next round. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu