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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 11FC0C433E0 for ; Thu, 14 May 2020 11:16:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E18FC206DA for ; Thu, 14 May 2020 11:16:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726726AbgENLQN (ORCPT ); Thu, 14 May 2020 07:16:13 -0400 Received: from foss.arm.com ([217.140.110.172]:34440 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726010AbgENLQM (ORCPT ); Thu, 14 May 2020 07:16:12 -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 E605A30E; Thu, 14 May 2020 04:16:11 -0700 (PDT) Received: from [192.168.122.166] (unknown [10.119.48.101]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 780353F305; Thu, 14 May 2020 04:16:11 -0700 (PDT) Subject: Re: Validating dma_mmap_coherent() parameters before calling (was Re: WARNING in memtype_reserve) To: Christoph Hellwig Cc: Greg KH , Hillf Danton , syzbot , Thomas Gleixner , linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, syzkaller-bugs@googlegroups.com, x86@kernel.org References: <000000000000f0d8d205a531f1a3@google.com> <20200509074507.GC1831917@kroah.com> <87wo5l4ecm.fsf@nanos.tec.linutronix.de> <20200513124445.GA1082735@kroah.com> <87zhab249p.fsf@nanos.tec.linutronix.de> <20200514035458.14760-1-hdanton@sina.com> <20200514061417.GA8367@lst.de> <20200514062750.GA1488715@kroah.com> <20200514063158.GA8780@lst.de> <8bdb3488-59d0-67ce-4822-e25dbd0dc42a@arm.com> <20200514111442.GA13813@lst.de> From: Jeremy Linton Message-ID: <83544950-e946-b696-9cf4-c7df097332b4@arm.com> Date: Thu, 14 May 2020 06:16:10 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200514111442.GA13813@lst.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/14/20 6:14 AM, Christoph Hellwig wrote: > On Thu, May 14, 2020 at 06:10:03AM -0500, Jeremy Linton wrote: >>> I only need to look at the commit for 3 seconds to tell you that it is >>> completely buggy. While using dma_mmap_coherent is fundamentally the >>> right thing and absolutely required for dma_alloc_* allocations, USB >>> also uses it's own local gen pool allocator or plain kmalloc for not >>> DMA capable controller. This need to use remap_pfn_range. I'm pretty >>> sure you hit one of those cases. >> >> ? The code path in question is usbdev_mmap() and the allocation is done ~13 >> lines lines before as a usb_alloc_coherent(). > > And did you take a look at how usb_alloc_coherent is implemented? That > should make it completely obvious that not all allocations come > from dma_alloc_*. No, your right, I noticed/remembered the usb_alloc vs dma_alloc difference right after sending that email, and was just about to say so. Sorry, you right. > >> That sort of makes sense, except for the above, and the fact that I would >> imagine the dma_mmap_coherent should be dealing with that case. I'm not >> really clear about the details of the GCE usb device here, but my first >> guess at this was the dma_pgprot() in dma_direct_mmap() is incorrectly >> picking a pgprot... > > No, dma_mmap_* / dma_direct_mmap has absolutely no business dealing > with memory that did not come from the DMA allocator. >