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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 4E4E3C433C1 for ; Fri, 19 Mar 2021 19:10:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0738C61962 for ; Fri, 19 Mar 2021 19:10:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230341AbhCSTKT (ORCPT ); Fri, 19 Mar 2021 15:10:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230273AbhCSTKF (ORCPT ); Fri, 19 Mar 2021 15:10:05 -0400 Received: from mail-wr1-x433.google.com (mail-wr1-x433.google.com [IPv6:2a00:1450:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ADA87C06174A for ; Fri, 19 Mar 2021 12:10:03 -0700 (PDT) Received: by mail-wr1-x433.google.com with SMTP id b9so10168212wrt.8 for ; Fri, 19 Mar 2021 12:10:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=jZpUFw5riLd0C9+mvdtvugCUovm7ZDUvByCOa9/76ZQ=; b=QhR+4KSqTHgaKnWXgqZDaD4oyvTkcghD7MmZhFA4mM/vgZNq/zvisfJ4lTbhpNMaDk WuvekNJUiEA/uWdTT1o59OVsNAcXORuTDKyS6drhuWf8q4bLYMPF208DZ7sK3aB2JtLo dQde/mDhVwjY5i7YnPoiQJN6FQ7596ueC8wIA= 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:in-reply-to; bh=jZpUFw5riLd0C9+mvdtvugCUovm7ZDUvByCOa9/76ZQ=; b=XRk6n8J55Z+bAeEj4nIctdewm1ph/7/UnJ3DTSovfHZWbJdLoSFbK9YWbTHn51z2XJ o0GFhXjLZcJ2P1Ye24tXQ3OFKBfkf+QEv/Ku9XLGrDdMyXeejjTf2VyvJ84SmAEiR9u3 ykg18VZZYvWX6zajaBVKRCv6xI7JRq8ou5XrlcJPj23+v9NI/jGoTiTaS/y3PsEv+4sP 2wkqyK+sYBEvP1K2dN33vHbgLy5A3ZP7xoQoAlPQ62Rln7ohmdtEAfwXLy9wSuCqc3At ToWJOH/QLHM5HMDnBtdH2EQ4hkIW1LrzQUuO8UHzgN4hFs9b/MoqHq4rvM1/3ly58sW+ jXxA== X-Gm-Message-State: AOAM531B61vp+SiYFmFzGY6vVQEWncbecxAcURndYaWSX0Cxr7Ovbj18 sf01LVHbDoiXR7x8sagKmQqEyw== X-Google-Smtp-Source: ABdhPJzFO9WN+CgE2/RgrKtksHm0n51FPIRyY4UczFIou1uJWBnUN6p6hqCHNzK6RXb0lDvwSgUmfw== X-Received: by 2002:a05:6000:120f:: with SMTP id e15mr5802818wrx.129.1616181002238; Fri, 19 Mar 2021 12:10:02 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id z2sm9085005wrv.47.2021.03.19.12.10.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 Mar 2021 12:10:01 -0700 (PDT) Date: Fri, 19 Mar 2021 20:09:59 +0100 From: Daniel Vetter To: DRI Development Cc: Daniel Vetter , stable@vger.kernel.org, John Hubbard , Daniel Vetter , Lucas Stach , Russell King , Christian Gmeiner , etnaviv@lists.freedesktop.org Subject: Re: [PATCH 1/2] drm/etnaviv: Use FOLL_FORCE for userptr Message-ID: References: <20210301095254.1946084-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210301095254.1946084-1-daniel.vetter@ffwll.ch> X-Operating-System: Linux phenom 5.7.0-1-amd64 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Mon, Mar 01, 2021 at 10:52:53AM +0100, Daniel Vetter wrote: > Nothing checks userptr.ro except this call to pup_fast, which means > there's nothing actually preventing userspace from writing to this. > Which means you can just read-only mmap any file you want, userptr it > and then write to it with the gpu. Not good. > > The right way to handle this is FOLL_WRITE | FOLL_FORCE, which will > break any COW mappings and update tracking for MAY_WRITE mappings so > there's no exploit and the vm isn't confused about what's going on. > For any legit use case there's no difference from what userspace can > observe and do. > > Cc: stable@vger.kernel.org > Cc: John Hubbard > Signed-off-by: Daniel Vetter > Cc: Lucas Stach > Cc: Russell King > Cc: Christian Gmeiner > Cc: etnaviv@lists.freedesktop.org Can I please have an ack on this so I can apply it? It's stuck. Thanks, Daniel > --- > drivers/gpu/drm/etnaviv/etnaviv_gem.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c > index 6d38c5c17f23..a9e696d05b33 100644 > --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c > +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c > @@ -689,7 +689,7 @@ static int etnaviv_gem_userptr_get_pages(struct etnaviv_gem_object *etnaviv_obj) > struct page **pages = pvec + pinned; > > ret = pin_user_pages_fast(ptr, num_pages, > - !userptr->ro ? FOLL_WRITE : 0, pages); > + FOLL_WRITE | FOLL_FORCE, pages); > if (ret < 0) { > unpin_user_pages(pvec, pinned); > kvfree(pvec); > -- > 2.30.0 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch