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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 305D8C282CE for ; Fri, 5 Apr 2019 17:31:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0A95020651 for ; Fri, 5 Apr 2019 17:31:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731955AbfDERbA (ORCPT ); Fri, 5 Apr 2019 13:31:00 -0400 Received: from foss.arm.com ([217.140.101.70]:53522 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730870AbfDERa4 (ORCPT ); Fri, 5 Apr 2019 13:30:56 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4D237168F; Fri, 5 Apr 2019 10:30:56 -0700 (PDT) Received: from [10.1.196.75] (e110467-lin.cambridge.arm.com [10.1.196.75]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B107B3F557; Fri, 5 Apr 2019 10:30:53 -0700 (PDT) Subject: Re: [PATCH 02/21] arm64/iommu: improve mmap bounds checking To: Christoph Hellwig Cc: Joerg Roedel , Catalin Marinas , Will Deacon , Tom Lendacky , iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20190327080448.5500-1-hch@lst.de> <20190327080448.5500-3-hch@lst.de> From: Robin Murphy Message-ID: <3629087c-a8cb-d66e-840b-cfee125bdf4c@arm.com> Date: Fri, 5 Apr 2019 18:30:52 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190327080448.5500-3-hch@lst.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? Robin. > Signed-off-by: Christoph Hellwig > --- > arch/arm64/mm/dma-mapping.c | 21 ++++++++------------- > 1 file changed, 8 insertions(+), 13 deletions(-) > > diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c > index be88beb2e377..e54288921e72 100644 > --- a/arch/arm64/mm/dma-mapping.c > +++ b/arch/arm64/mm/dma-mapping.c > @@ -73,19 +73,9 @@ static int __swiotlb_get_sgtable_page(struct sg_table *sgt, > static int __swiotlb_mmap_pfn(struct vm_area_struct *vma, > unsigned long pfn, size_t size) > { > - int ret = -ENXIO; > - unsigned long nr_vma_pages = vma_pages(vma); > - unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT; > - unsigned long off = vma->vm_pgoff; > - > - if (off < nr_pages && nr_vma_pages <= (nr_pages - off)) { > - ret = remap_pfn_range(vma, vma->vm_start, > - pfn + off, > - vma->vm_end - vma->vm_start, > - vma->vm_page_prot); > - } > - > - return ret; > + return remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff, > + vma->vm_end - vma->vm_start, > + vma->vm_page_prot); > } > #endif /* CONFIG_IOMMU_DMA */ > > @@ -241,6 +231,8 @@ static int __iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma, > void *cpu_addr, dma_addr_t dma_addr, size_t size, > unsigned long attrs) > { > + unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT; > + unsigned long off = vma->vm_pgoff; > struct vm_struct *area; > int ret; > > @@ -249,6 +241,9 @@ static int __iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma, > if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret)) > return ret; > > + if (off >= nr_pages || vma_pages(vma) > nr_pages - off) > + return -ENXIO; > + > if (!is_vmalloc_addr(cpu_addr)) { > unsigned long pfn = page_to_pfn(virt_to_page(cpu_addr)); > return __swiotlb_mmap_pfn(vma, pfn, size); >