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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76D90C433F5 for ; Tue, 10 May 2022 22:01:26 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DF0A86B0071; Tue, 10 May 2022 18:01:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D9EBB6B0072; Tue, 10 May 2022 18:01:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C8E2B6B0073; Tue, 10 May 2022 18:01:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id BA8CA6B0071 for ; Tue, 10 May 2022 18:01:25 -0400 (EDT) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 8A44131649 for ; Tue, 10 May 2022 22:01:25 +0000 (UTC) X-FDA: 79451205330.02.04CF455 Received: from mail-pf1-f171.google.com (mail-pf1-f171.google.com [209.85.210.171]) by imf29.hostedemail.com (Postfix) with ESMTP id 483961200B8 for ; Tue, 10 May 2022 22:01:18 +0000 (UTC) Received: by mail-pf1-f171.google.com with SMTP id a11so336640pff.1 for ; Tue, 10 May 2022 15:01:24 -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=i8lQi4uyiCT7jQZzDyA2atJwe0TBijGbcFdUMtd4OMM=; b=ZSoJ+FUKlcrZBAptXSalTXcAE2E15WyyI4QVVMM3HAvlapUWJ46fr7YKgN6pzaUcQY ocM7hwQDztfpxL/udshq3B24X4fB2YnaTYJkH7Gcu2gT6vAdiveOztv30KrVQdvwo8LU 4GdOKu1d1qwkkKciPdkP3SKtIeS9tcuuQiyvE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=i8lQi4uyiCT7jQZzDyA2atJwe0TBijGbcFdUMtd4OMM=; b=nFoFtA81WRr0L2VIkpKQtmrMAK8jDjT/GivzkfQG0EgRwDxn9TrpiZLsW0Af8RZxh3 S7zYODJ8/+H3bGn5ldGACF5mV0MEwzv0mgTikVjj0/+qXBaNYlRDA0gNxR6zYW7gEKmi p7H+tszorq4yulnN86uCZYBYU+K2Z7gl4+7MP4KeCeJOVTKTDF3PCz1AhroXLdoNJ22z tyzN/uTasWG+l4XOuN4TPuE8dKFBFmBMPWJv9Upsu8AcPSncNDzTH9epElrT1sTOqCsr 8tSW96c5t68vEyhVVXYydIcKeQFFuzlXrW+NsI/emUa3j3Sz7UjvddLT9gZdj3Ir22iT haXg== X-Gm-Message-State: AOAM530mC9Ax9aa29O8JajEo4zySWbZEtZv+BmPHc+aYKT54xDkWYFuy njuWWfuZyk6sK59rLz4PkhvjJw== X-Google-Smtp-Source: ABdhPJzAvs0guM22nqTRC61X8dIP2hQy1mtahN5BxBPCgqBrEtCGruh9ewsVgBKVkVnPtLekHh0x1g== X-Received: by 2002:a63:694a:0:b0:3aa:e962:db29 with SMTP id e71-20020a63694a000000b003aae962db29mr18341240pgc.421.1652220083930; Tue, 10 May 2022 15:01:23 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id h7-20020a62b407000000b0050dc7628141sm51069pfn.27.2022.05.10.15.01.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 May 2022 15:01:23 -0700 (PDT) Date: Tue, 10 May 2022 15:01:22 -0700 From: Kees Cook To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH 1/4] mm/usercopy: Check kmap addresses properly Message-ID: <202205101455.24F5C046F@keescook> References: <20220110231530.665970-1-willy@infradead.org> <20220110231530.665970-2-willy@infradead.org> <20220509203742.0f4adfa4004e51e66c1c9a20@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220509203742.0f4adfa4004e51e66c1c9a20@linux-foundation.org> X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 483961200B8 X-Stat-Signature: spc5o1mu3mq15phfi3urs18cqc97i8c1 X-Rspam-User: Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=ZSoJ+FUK; spf=pass (imf29.hostedemail.com: domain of keescook@chromium.org designates 209.85.210.171 as permitted sender) smtp.mailfrom=keescook@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-HE-Tag: 1652220078-301915 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, May 09, 2022 at 08:37:42PM -0700, Andrew Morton wrote: > On Mon, 10 Jan 2022 23:15:27 +0000 "Matthew Wilcox (Oracle)" wrote: > > > If you are copying to an address in the kmap region, you may not copy > > across a page boundary, > > In the source, the destination or in both, and why may we not? This depends on direction. For copying to userspace, the source (kmap). For copying from userspace, the destination (kmap). > > no matter what the size of the underlying > > allocation. You can't kmap() a slab page because slab pages always > > come from low memory. As in it'll be processed as a slab page instead of kmap by the usercopy checks? -- Kees Cook