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=-6.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9805FC47095 for ; Wed, 7 Oct 2020 17:27:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 280312168B for ; Wed, 7 Oct 2020 17:27:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="mSF3jlLK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728444AbgJGR1u (ORCPT ); Wed, 7 Oct 2020 13:27:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59512 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726348AbgJGR1t (ORCPT ); Wed, 7 Oct 2020 13:27:49 -0400 Received: from mail-qt1-x841.google.com (mail-qt1-x841.google.com [IPv6:2607:f8b0:4864:20::841]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5F990C0613D3 for ; Wed, 7 Oct 2020 10:27:49 -0700 (PDT) Received: by mail-qt1-x841.google.com with SMTP id d1so2604017qtr.6 for ; Wed, 07 Oct 2020 10:27:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=XbSoU+/at8nS4vwGrWdy12hS6b+RYvRwUOTYRSNB06Q=; b=mSF3jlLKHl2GcWOtjisnFuOxmsafdLuRV7HNQszKRHTbX7yrWh+1uuimlnTVBDf88S 7CDIDMQGVG9iRv64l0dGVTOGsF3HhoVCmCeCFmDoV09KS3pUl6DC8vC3fTvvt2cweotS YfhKySivQyKZUy5Qq80V3s1ZqG50WhxQuoVnwHYZe7OK1Xk2CZbcO9rDgpzCxYLE695p iM3zaabJqTXzIZDyKFOBFSJJu8gE182ca6m7suRvcG0u6/EkdQ4bhJV4U+DEo5V7zW7u S96CIynxOtOJjWv1pdwcNaqEUxAlUPVqbissjAJxdOugEaGgQF1dKaRPG7Vtfa/bgluo JjMA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=XbSoU+/at8nS4vwGrWdy12hS6b+RYvRwUOTYRSNB06Q=; b=R5DOtzKTJLFzmilFO2keRwLCS6AdYH0Cto7Hnl5D8gg8mHHPBkmjr2oza+mDL2nsCt gdi3BN28AykwBJt5OlhFcVxCdxDCGq8+FPuBTG7j5Cd1Q+qDwBH3N4j/KMqC2+8jGM+6 Ho6DuLny4aSKKubPBkDgd2bdm4P1M2da4mlT0HTiOv+LQZl0ScEYc6zK6YtbCcVTuxMV i/wB1yOW2KKh0PTp9wuwFCl7IGpAJWwJrG8bltzeDk52tTRZiKfjOqZGOJ7XeG6jYHIK Vlcb+A4iHB/9tkIdQ3/Ll94UgbC7tBygEUB/zQbAAc7Cf7q//KTtsusbhfyIfrxct+I2 3m1w== X-Gm-Message-State: AOAM532xA9ONQmFc6P4YGBb+B+62SEITp77Vb/wlu46NUfnfm9p4agKh /UBRWrjmBdDp13l5n/LlScZOYQ== X-Google-Smtp-Source: ABdhPJzBzIEuFCTfuv3ULvENiYmE1q5S6ZKvaoPSvLERT9h4HN4R+RXmtJoeCi0hQLY2ayjG0AcA6w== X-Received: by 2002:ac8:37ef:: with SMTP id e44mr4247866qtc.342.1602091668463; Wed, 07 Oct 2020 10:27:48 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-156-34-48-30.dhcp-dynamic.fibreop.ns.bellaliant.net. [156.34.48.30]) by smtp.gmail.com with ESMTPSA id t10sm1904322qkt.55.2020.10.07.10.27.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Oct 2020 10:27:47 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kQDEA-0010sP-Uz; Wed, 07 Oct 2020 14:27:46 -0300 Date: Wed, 7 Oct 2020 14:27:46 -0300 From: Jason Gunthorpe To: Daniel Vetter Cc: DRI Development , LKML , kvm@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org, linux-s390@vger.kernel.org, Dan Williams , Kees Cook , Rik van Riel , Benjamin Herrensmidt , Dave Airlie , Hugh Dickins , Andrew Morton , John Hubbard , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Jan Kara , Daniel Vetter Subject: Re: [PATCH 07/13] mm: close race in generic_access_phys Message-ID: <20201007172746.GU5177@ziepe.ca> References: <20201007164426.1812530-1-daniel.vetter@ffwll.ch> <20201007164426.1812530-8-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20201007164426.1812530-8-daniel.vetter@ffwll.ch> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 07, 2020 at 06:44:20PM +0200, Daniel Vetter wrote: > Way back it was a reasonable assumptions that iomem mappings never > change the pfn range they point at. But this has changed: > > - gpu drivers dynamically manage their memory nowadays, invalidating > ptes with unmap_mapping_range when buffers get moved > > - contiguous dma allocations have moved from dedicated carvetouts to > cma regions. This means if we miss the unmap the pfn might contain > pagecache or anon memory (well anything allocated with GFP_MOVEABLE) > > - even /dev/mem now invalidates mappings when the kernel requests that > iomem region when CONFIG_IO_STRICT_DEVMEM is set, see 3234ac664a87 > ("/dev/mem: Revoke mappings when a driver claims the region") > > Accessing pfns obtained from ptes without holding all the locks is > therefore no longer a good idea. Fix this. > > Since ioremap might need to manipulate pagetables too we need to drop > the pt lock and have a retry loop if we raced. > > While at it, also add kerneldoc and improve the comment for the > vma_ops->access function. It's for accessing, not for moving the > memory from iomem to system memory, as the old comment seemed to > suggest. > > References: 28b2ee20c7cb ("access_process_vm device memory infrastructure") > Cc: Jason Gunthorpe > Cc: Dan Williams > Cc: Kees Cook > Cc: Rik van Riel > Cc: Benjamin Herrensmidt > Cc: Dave Airlie > Cc: Hugh Dickins > Cc: Andrew Morton > Cc: John Hubbard > Cc: Jérôme Glisse > Cc: Jan Kara > Cc: Dan Williams > Cc: linux-mm@kvack.org > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-samsung-soc@vger.kernel.org > Cc: linux-media@vger.kernel.org > Signed-off-by: Daniel Vetter > --- > include/linux/mm.h | 3 ++- > mm/memory.c | 44 ++++++++++++++++++++++++++++++++++++++++++-- > 2 files changed, 44 insertions(+), 3 deletions(-) This does seem to solve the race with revoke_devmem(), but it is really ugly. It would be much nicer to wrap a rwsem around this access and the unmap. Any place using it has a nice linear translation from vm_off to pfn, so I don't think there is a such a good reason to use follow_pte in the first place. ie why not the helper be this: int generic_access_phys(unsigned long pfn, unsigned long pgprot, void *buf, size_t len, bool write) Then something like dev/mem would compute pfn and obtain the lock: dev_access(struct vm_area_struct *vma, unsigned long addr, void *buf, int len, int write) { cpu_addr = vma->vm_pgoff*PAGE_SIZE + (addr - vma->vm_start)); /* FIXME: Has to be over each page of len */ if (!devmem_is_allowed_access(PHYS_PFN(cpu_addr/4096))) return -EPERM; down_read(&mem_sem); generic_access_phys(cpu_addr/4096, pgprot_val(vma->vm_page_prot), buf, len, write); up_read(&mem_sem); } The other cases looked simpler because they don't revoke, here the mmap_sem alone should be enough protection, they would just need to provide the linear translation to pfn. What do you think? Jason 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=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C5DC2C41604 for ; Wed, 7 Oct 2020 17:29:29 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 544172168B for ; Wed, 7 Oct 2020 17:29:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="K/uY+TGm"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="mSF3jlLK" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 544172168B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=TAvmzvEeGmwSgB2y3+SsMgKH0wVxjsFDSs9EjzLhEXM=; b=K/uY+TGmpcdPglfsQKpAZr3dL SyxogQqqB1biUqs1+pi9WXbSxyQP3XT1E80ESj9zmk8JgXiywKbdBd4UkFVJ8HD7h05bPzJ70TxiL NwTGtK7TDyBv5BqOZ06AY3UM5tcyaebJpsDyz/3eUAbXOaOFbPCGvw5/4/NUkjeflcMBnyeQ62iwh IKAxqziNFW+Y2ccLlqWofXW11yK7dQuW/EbES+AD8EKAtmBkjNfDAL75s/fU0pDIcB3C66/cFOd4b oEek2dCanETjrS3zkJZ8RjXJrc8oXQICvrG0AUGWc99qntDqWbzVN0FTIckkNeslfUyHVF7+ccSeL SwfNqlukw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kQDEH-0008Ba-HC; Wed, 07 Oct 2020 17:27:53 +0000 Received: from mail-qt1-x842.google.com ([2607:f8b0:4864:20::842]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kQDEE-0008AV-DZ for linux-arm-kernel@lists.infradead.org; Wed, 07 Oct 2020 17:27:51 +0000 Received: by mail-qt1-x842.google.com with SMTP id c23so2629700qtp.0 for ; Wed, 07 Oct 2020 10:27:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=XbSoU+/at8nS4vwGrWdy12hS6b+RYvRwUOTYRSNB06Q=; b=mSF3jlLKHl2GcWOtjisnFuOxmsafdLuRV7HNQszKRHTbX7yrWh+1uuimlnTVBDf88S 7CDIDMQGVG9iRv64l0dGVTOGsF3HhoVCmCeCFmDoV09KS3pUl6DC8vC3fTvvt2cweotS YfhKySivQyKZUy5Qq80V3s1ZqG50WhxQuoVnwHYZe7OK1Xk2CZbcO9rDgpzCxYLE695p iM3zaabJqTXzIZDyKFOBFSJJu8gE182ca6m7suRvcG0u6/EkdQ4bhJV4U+DEo5V7zW7u S96CIynxOtOJjWv1pdwcNaqEUxAlUPVqbissjAJxdOugEaGgQF1dKaRPG7Vtfa/bgluo JjMA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=XbSoU+/at8nS4vwGrWdy12hS6b+RYvRwUOTYRSNB06Q=; b=mQ1VBdmLQI2Ib/H9NZa41NW0491inIMei+IxV8AVwWVBtolqZyI4yrXtoHKWncGJmQ Pb8UVCybUpKpxIVs/UrbmPJKkRNnoenMAX1eXcmXAslaQT9CCE0fsgptnYJHGuE0iG0s QJp+JlDxw5feRmipQYdD45elHvOnR6hN/nqGBagBldz2yq4s/DYKhr5aM7HcVrq3gn2r Po3x6ZbftHWxP1qSXMhyLnaQBtbM6xhac1U9K8pyR5vTna4vIbIv9VP6JU1brfJQar8N gHq4evu+5KabkoWO+weDdE0YJe/YDpRI/32cOQ6++Uy+qbfwPG5GYekZ8PC1wCUgFbxe yPQA== X-Gm-Message-State: AOAM532UljBkT6+748ISYhTBr4SV6VFw7XrbrstvZEbR/+plDiW/N2p8 d0cbsMeLubTV+Dwp8CQqsc4GlA== X-Google-Smtp-Source: ABdhPJzBzIEuFCTfuv3ULvENiYmE1q5S6ZKvaoPSvLERT9h4HN4R+RXmtJoeCi0hQLY2ayjG0AcA6w== X-Received: by 2002:ac8:37ef:: with SMTP id e44mr4247866qtc.342.1602091668463; Wed, 07 Oct 2020 10:27:48 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-156-34-48-30.dhcp-dynamic.fibreop.ns.bellaliant.net. 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[156.34.48.30]) by smtp.gmail.com with ESMTPSA id t10sm1904322qkt.55.2020.10.07.10.27.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Oct 2020 10:27:47 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kQDEA-0010sP-Uz; Wed, 07 Oct 2020 14:27:46 -0300 Date: Wed, 7 Oct 2020 14:27:46 -0300 From: Jason Gunthorpe To: Daniel Vetter Subject: Re: [PATCH 07/13] mm: close race in generic_access_phys Message-ID: <20201007172746.GU5177@ziepe.ca> References: <20201007164426.1812530-1-daniel.vetter@ffwll.ch> <20201007164426.1812530-8-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201007164426.1812530-8-daniel.vetter@ffwll.ch> X-Mailman-Approved-At: Thu, 08 Oct 2020 07:20:54 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390@vger.kernel.org, Rik van Riel , linux-samsung-soc@vger.kernel.org, Jan Kara , Kees Cook , kvm@vger.kernel.org, Dave Airlie , LKML , DRI Development , linux-mm@kvack.org, =?utf-8?B?SsOpcsO0bWU=?= Glisse , Daniel Vetter , John Hubbard , Hugh Dickins , Dan Williams , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Content-Type: text/plain; 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