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=-13.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 11AB2ECE58C for ; Fri, 11 Oct 2019 09:33:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E1BA021A4A for ; Fri, 11 Oct 2019 09:33:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727744AbfJKJdw (ORCPT ); Fri, 11 Oct 2019 05:33:52 -0400 Received: from foss.arm.com ([217.140.110.172]:54528 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727715AbfJKJdv (ORCPT ); Fri, 11 Oct 2019 05:33:51 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E49D3337; Fri, 11 Oct 2019 02:33:50 -0700 (PDT) Received: from [192.168.1.123] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 25DC13F703; Fri, 11 Oct 2019 02:33:49 -0700 (PDT) Subject: Re: [PATCH v3 1/2] dma-mapping: Add vmap checks to dma_map_single() To: Greg Kroah-Hartman , Kees Cook Cc: Christoph Hellwig , Laura Abbott , Marek Szyprowski , Jesper Dangaard Brouer , Allison Randal , Thomas Gleixner , Stephen Boyd , Dan Carpenter , Semmle Security Reports , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <20191010222829.21940-1-keescook@chromium.org> <20191010222829.21940-2-keescook@chromium.org> <20191011050208.GA978459@kroah.com> From: Robin Murphy Message-ID: <4f559fe1-a867-c3ca-eed2-1962d01d5346@arm.com> Date: Fri, 11 Oct 2019 10:33:17 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <20191011050208.GA978459@kroah.com> 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 2019-10-11 6:02 am, Greg Kroah-Hartman wrote: > On Thu, Oct 10, 2019 at 03:28:28PM -0700, Kees Cook wrote: >> As we've seen from USB and other areas[1], we need to always do runtime >> checks for DMA operating on memory regions that might be remapped. This >> adds vmap checks (similar to those already in USB but missing in other >> places) into dma_map_single() so all callers benefit from the checking. >> >> [1] https://git.kernel.org/linus/3840c5b78803b2b6cc1ff820100a74a092c40cbb >> >> Suggested-by: Laura Abbott >> Signed-off-by: Kees Cook >> --- >> include/linux/dma-mapping.h | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h >> index 4a1c4fca475a..ff4e91c66f44 100644 >> --- a/include/linux/dma-mapping.h >> +++ b/include/linux/dma-mapping.h >> @@ -583,6 +583,12 @@ static inline unsigned long dma_get_merge_boundary(struct device *dev) >> static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr, >> size_t size, enum dma_data_direction dir, unsigned long attrs) >> { >> + /* DMA must never operate on areas that might be remapped. */ >> + if (unlikely(is_vmalloc_addr(ptr))) { >> + dev_warn_once(dev, "bad map: %zu bytes in vmalloc\n", size); > > Can we get a bit better error text here? In USB we were at least giving > people a hint as to what went wrong, "bad map" might not really make > that much sense to a USB developer as to what they needed to do to fix > this issue. Agreed, something along the lines of "dma_map_single of vmalloc'ed buffer..." might be clearer. Also I'd be inclined to use dev_WARN_ONCE() to include a diagnostically-useful backtrace, as the existing USB code would. Thanks, Robin.