From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-f198.google.com (mail-lj1-f198.google.com [209.85.208.198]) by kanga.kvack.org (Postfix) with ESMTP id EED578E0004 for ; Fri, 7 Dec 2018 15:38:14 -0500 (EST) Received: by mail-lj1-f198.google.com with SMTP id x9-v6so1378429ljd.21 for ; Fri, 07 Dec 2018 12:38:14 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id m23sor1444670lfl.47.2018.12.07.12.38.13 for (Google Transport Security); Fri, 07 Dec 2018 12:38:13 -0800 (PST) MIME-Version: 1.0 References: <20181206184343.GA30569@jordon-HP-15-Notebook-PC> In-Reply-To: From: Souptick Joarder Date: Sat, 8 Dec 2018 02:11:49 +0530 Message-ID: Subject: Re: [PATCH v3 6/9] iommu/dma-iommu.c: Convert to use vm_insert_range Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: robin.murphy@arm.com Cc: Andrew Morton , Matthew Wilcox , Michal Hocko , joro@8bytes.org, Linux-MM , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org On Fri, Dec 7, 2018 at 7:17 PM Robin Murphy wrote: > > 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). So this should something similar to -> return vm_insert_range(vma, vma->vm_start, pages + vma->vm_pgoff, count - vma->vm_pgoff);