From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot1-f72.google.com (mail-ot1-f72.google.com [209.85.210.72]) by kanga.kvack.org (Postfix) with ESMTP id BACF76B7DFC for ; Fri, 7 Dec 2018 08:47:24 -0500 (EST) Received: by mail-ot1-f72.google.com with SMTP id a89so1820147otc.8 for ; Fri, 07 Dec 2018 05:47:24 -0800 (PST) Received: from foss.arm.com (usa-sjc-mx-foss1.foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id t25si1497687oth.275.2018.12.07.05.47.23 for ; Fri, 07 Dec 2018 05:47:23 -0800 (PST) Subject: Re: [PATCH v3 6/9] iommu/dma-iommu.c: Convert to use vm_insert_range References: <20181206184343.GA30569@jordon-HP-15-Notebook-PC> From: Robin Murphy Message-ID: Date: Fri, 7 Dec 2018 13:47:19 +0000 MIME-Version: 1.0 In-Reply-To: <20181206184343.GA30569@jordon-HP-15-Notebook-PC> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Souptick Joarder , akpm@linux-foundation.org, willy@infradead.org, mhocko@suse.com, joro@8bytes.org Cc: linux-mm@kvack.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org On 06/12/2018 18:43, Souptick Joarder wrote: > Convert to use vm_insert_range() to map range of kernel > memory to user vma. > > Signed-off-by: Souptick Joarder > Reviewed-by: Matthew Wilcox > --- > drivers/iommu/dma-iommu.c | 13 +++---------- > 1 file changed, 3 insertions(+), 10 deletions(-) > > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c > index d1b0475..a2c65e2 100644 > --- a/drivers/iommu/dma-iommu.c > +++ b/drivers/iommu/dma-iommu.c > @@ -622,17 +622,10 @@ struct page **iommu_dma_alloc(struct device *dev, size_t size, gfp_t gfp, > > int iommu_dma_mmap(struct page **pages, size_t size, struct vm_area_struct *vma) > { > - unsigned long uaddr = vma->vm_start; > - unsigned int i, count = PAGE_ALIGN(size) >> PAGE_SHIFT; > - int ret = -ENXIO; > + unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT; > > - for (i = vma->vm_pgoff; i < count && uaddr < vma->vm_end; i++) { > - ret = vm_insert_page(vma, uaddr, pages[i]); > - if (ret) > - break; > - uaddr += PAGE_SIZE; > - } > - return ret; > + return vm_insert_range(vma, vma->vm_start, > + pages + vma->vm_pgoff, count); You also need to adjust count to compensate for the pages skipped by vm_pgoff, otherwise you've got an out-of-bounds dereference triggered from userspace, which is pretty high up the "not good" scale (not to mention the entire call would then propagate -EFAULT back from vm_insert_page() and thus always appear to fail for nonzero offsets). Robin. > } > > static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys, >