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 EB404C433DF for ; Thu, 14 May 2020 11:10:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1915206DA for ; Thu, 14 May 2020 11:10:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726094AbgENLKG (ORCPT ); Thu, 14 May 2020 07:10:06 -0400 Received: from foss.arm.com ([217.140.110.172]:34344 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725925AbgENLKF (ORCPT ); Thu, 14 May 2020 07:10:05 -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 D3E0230E; Thu, 14 May 2020 04:10:04 -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 2CA6F3F305; Thu, 14 May 2020 04:10:04 -0700 (PDT) Subject: Re: Validating dma_mmap_coherent() parameters before calling (was Re: WARNING in memtype_reserve) To: Christoph Hellwig , Greg KH Cc: 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> From: Jeremy Linton Message-ID: <8bdb3488-59d0-67ce-4822-e25dbd0dc42a@arm.com> Date: Thu, 14 May 2020 06:10:03 -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: <20200514063158.GA8780@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 Hi, On 5/14/20 1:31 AM, Christoph Hellwig wrote: > On Thu, May 14, 2020 at 08:27:50AM +0200, Greg KH wrote: >> On Thu, May 14, 2020 at 08:14:17AM +0200, Christoph Hellwig wrote: >>> Guys, can you please start formal thread on this? I have no >>> idea where this came from and what the rationale is. Btw, if the >>> pfn is crap in dma_direct_mmap then the dma_addr_t passed in is >>> crap, as it is derived from that. What is the caller, and how is >>> this triggered? >> >> >> Ok, to summarize, commit 2bef9aed6f0e ("usb: usbfs: correct kernel->user >> page attribute mismatch") changed a call from remap_pfn_range() to >> dma_mmap_coherent() for usb data buffers being sent from userspace. > > 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(). > > The logic should be something like: > > if (hcd->localmem_pool || !hcd_uses_dma(hcd)) > remap_pfn_range() > else > dma_mmap_coherent() > 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...