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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 6F1D8C4CEC9 for ; Tue, 17 Sep 2019 17:39:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 49A5C2067B for ; Tue, 17 Sep 2019 17:39:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="NtTZWOJ6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731315AbfIQRjx (ORCPT ); Tue, 17 Sep 2019 13:39:53 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:39197 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726607AbfIQRjx (ORCPT ); Tue, 17 Sep 2019 13:39:53 -0400 Received: by mail-pg1-f195.google.com with SMTP id u17so2384128pgi.6 for ; Tue, 17 Sep 2019 10:39:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=yQGk0/8lgiYPogMBH7GGBJWsq/bIXk08DULJA4Ggl0k=; b=NtTZWOJ6sZPprJOVH0W4hwFThisJKK+mS/VHocfVHVb2P9H2l9T5aHpChwouDxkwmE P49mEJJBAVVcwAOr9zUQvc3TY6g7qH1YnPBmLL6C8kaZ+bVjQzQTzqDTut2MaiTkY9wl QF6VMIptGZdvKaN6CHCHDorvDVZ2wL8ePNFV0= 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=yQGk0/8lgiYPogMBH7GGBJWsq/bIXk08DULJA4Ggl0k=; b=KjkuauF9glcrZMM/DD5wpBrsXSXKekU226s3FLryycbkh+Zxm0NCHNFK3WzI7S2Dzh 00dtNEAmToDQX9xte14Dh/+3v50oBWSbI3BiElezz2dt44q+HF+h+O4spEwn+4ifFHEO lGxEGabMUdyW/UMpK4RxDU+A1tl3qN0tw/EovajnXCIkLSrtf+vuRm4uL166KtgMn2Iw StDkq9bcyaXqij/sx+VK+XmHYEsCOjtNIrOJZVpPPQ+Jn1JHLOOBS71y3yUWRo7fX05U HsVqBXsNw5Sw0oPoHxfWvTbZuZsWqUWcWzS22A2fmqGX3mZcHA937IXyeocCHKFl50P6 kZdA== X-Gm-Message-State: APjAAAVx6+i01T2xzsBeh+ajXV4bun42KBqTh3m1EM9sPcafKvgJqgZL QTUOmq3uWB8s3iGIZqJ1byscvA== X-Google-Smtp-Source: APXvYqy6+hMb62AAD7PQRSOuTFktsmPGOjE+m8dJyhXRgqu8ZVw0TdiA88ecI5b6khAzl2L7X7g00w== X-Received: by 2002:a63:3585:: with SMTP id c127mr8016pga.93.1568741992410; Tue, 17 Sep 2019 10:39:52 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id w7sm3008939pjn.1.2019.09.17.10.39.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Sep 2019 10:39:51 -0700 (PDT) Date: Tue, 17 Sep 2019 10:39:50 -0700 From: Kees Cook To: Matthew Wilcox Cc: Randy Dunlap , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] usercopy: Skip HIGHMEM page checking Message-ID: <201909171039.09E75C2@keescook> References: <201909161431.E69B29A0@keescook> <20190917003209.GS29434@bombadil.infradead.org> <201909162003.FEEAC65@keescook> <20190917163606.GU29434@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190917163606.GU29434@bombadil.infradead.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 17, 2019 at 09:36:06AM -0700, Matthew Wilcox wrote: > If the copy has the correct bounds, the 'wholly within one base page' > check will pass and it'll return. If the copy does span a page, > the virt_to_head_page(end) call will return something bogus, then the > PageReserved and CMA test will cause the usercopy_abort() test to fail. > > So I think your first patch is the right patch. Okay, good points. I'll respin... -- Kees Cook