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=-8.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,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 9F1B6C43387 for ; Tue, 18 Dec 2018 09:38:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 69399217D9 for ; Tue, 18 Dec 2018 09:38:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="T/XXcNpm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726479AbeLRJia (ORCPT ); Tue, 18 Dec 2018 04:38:30 -0500 Received: from pandora.armlinux.org.uk ([78.32.30.218]:39152 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726417AbeLRJi3 (ORCPT ); Tue, 18 Dec 2018 04:38:29 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2014; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=Idm6aAp6sVxp+WzgidWgoDIbk+vjPvG/6DZo0UnmYpo=; b=T/XXcNpmpTPZ2JEB0Sab25zLX 8/xz1L5y6CBdrCarLdVWa9xCmzsYdsdpj5Z8Wy2pTnnCyfpW+ueh3jUrQtw9wBkbGwVN2h9oS17qc bKKyMsK3KSduRHRMpdKMfYPSXTU3QsErFZnmqgRirzRJASjsPEHOTiOfzZ5t806tbIQ3M=; Received: from n2100.armlinux.org.uk ([2002:4e20:1eda:1:214:fdff:fe10:4f86]:42644) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.90_1) (envelope-from ) id 1gZBp9-0005ML-2L; Tue, 18 Dec 2018 09:37:59 +0000 Received: from linux by n2100.armlinux.org.uk with local (Exim 4.90_1) (envelope-from ) id 1gZBp6-0005U0-8m; Tue, 18 Dec 2018 09:37:56 +0000 Date: Tue, 18 Dec 2018 09:37:54 +0000 From: Russell King - ARM Linux To: Souptick Joarder Cc: akpm@linux-foundation.org, willy@infradead.org, mhocko@suse.com, robin.murphy@arm.com, iamjoonsoo.kim@lge.com, treding@nvidia.com, keescook@chromium.org, m.szyprowski@samsung.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v4 2/9] arch/arm/mm/dma-mapping.c: Convert to use vm_insert_range Message-ID: <20181218093754.GI26090@n2100.armlinux.org.uk> References: <20181217202209.GA8859@jordon-HP-15-Notebook-PC> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181217202209.GA8859@jordon-HP-15-Notebook-PC> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 18, 2018 at 01:52:09AM +0530, Souptick Joarder wrote: > Convert to use vm_insert_range() to map range of kernel > memory to user vma. > > Signed-off-by: Souptick Joarder > --- > arch/arm/mm/dma-mapping.c | 21 +++++++-------------- > 1 file changed, 7 insertions(+), 14 deletions(-) > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index 661fe48..7cbcde5 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c > @@ -1582,31 +1582,24 @@ static int __arm_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 uaddr = vma->vm_start; > - unsigned long usize = vma->vm_end - vma->vm_start; > + unsigned long page_count = vma_pages(vma); > struct page **pages = __iommu_get_pages(cpu_addr, attrs); > unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT; > unsigned long off = vma->vm_pgoff; > + int err; > > if (!pages) > return -ENXIO; > > - if (off >= nr_pages || (usize >> PAGE_SHIFT) > nr_pages - off) > + if (off >= nr_pages) > return -ENXIO; Are you sure you can make this change? You are restricting the offset to be within 0..nr_pages which ensures that the initial struct page that is passed to vm_insert_range() is valid, but I think the removal of the following check is unsafe. Your new vm_insert_range() function only checks page_count <= vma_pages(vma), which it will be since it _is_ vma_pages(vma). With the removal of the second condition, there will be nothing checking that (eg) off may be nr_pages - 1, and page_count=50, meaning that vm_insert_range() will walk off the end of the page array. Please take another look at this. What about the other callsites of your new function - do they have the same issue? -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up