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=-13.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 1AB00CA9EC5 for ; Wed, 30 Oct 2019 18:09:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DD90C2087E for ; Wed, 30 Oct 2019 18:09:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727822AbfJ3SJZ (ORCPT ); Wed, 30 Oct 2019 14:09:25 -0400 Received: from verein.lst.de ([213.95.11.211]:47070 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726259AbfJ3SJZ (ORCPT ); Wed, 30 Oct 2019 14:09:25 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id A18E468B05; Wed, 30 Oct 2019 19:09:21 +0100 (CET) Date: Wed, 30 Oct 2019 19:09:21 +0100 From: Christoph Hellwig To: Greg Kroah-Hartman Cc: Kees Cook , Christoph Hellwig , Robin Murphy , 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 Subject: Re: [PATCH v4 1/2] dma-mapping: Add vmap checks to dma_map_single() Message-ID: <20191030180921.GB19366@lst.de> References: <20191029213423.28949-1-keescook@chromium.org> <20191029213423.28949-2-keescook@chromium.org> <20191030091849.GA637042@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191030091849.GA637042@kroah.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 30, 2019 at 10:18:49AM +0100, Greg Kroah-Hartman wrote: > On Tue, Oct 29, 2019 at 02:34:22PM -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..54de3c496407 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 (dev_WARN_ONCE(dev, is_vmalloc_addr(ptr), > > + "wanted %zu bytes mapped in vmalloc\n", size)) { > > + return DMA_MAPPING_ERROR; > > + } > > That's a very odd error string, I know if I saw it for the first time, I > would have no idea what it meant. The USB message at least gives you a > bit more context as to what went wrong and how to fix it. > > How about something like "Memory is not DMA capabable, please fix the > allocation of it to be correct", or "non-dma-able memory was attempted > to be mapped, but this is impossible to to" or something else. I've fixed the message to "rejecting DMA map of vmalloc memory" and applied the patch.