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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 7ACF3FA372C for ; Fri, 8 Nov 2019 06:33:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5023B21882 for ; Fri, 8 Nov 2019 06:33:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="sG/5Iy/R" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727433AbfKHGdJ (ORCPT ); Fri, 8 Nov 2019 01:33:09 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:46636 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725372AbfKHGdI (ORCPT ); Fri, 8 Nov 2019 01:33:08 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=qCauJZ5vwFE0q6fN8aq4sFtrLeNJgvenOfvg0GpdMWM=; b=sG/5Iy/R93fNdCNserw/hcK8F I/tl7i3svTZIlLBYVvm+NfxSZjsLxC51ymu9r87M1bcceDqDqzElzGH4E21ZuKNGpCjCF2a3WhE5/ aHceB75r4dDQHPWrsnertyu9LhreTunp6OttSkF3mfFAFB8UyZHLgY4VlFe3F3U+gU9tQP8euB1Al O41BzkChjzsSrgPwft5xFbCUSfvSdd+z5qjlvYD27PHjVupeohgKhz9l3sivmFUVj3CAW0v4MZZGa Nf+34EHDPZULFBQZufZmCw7CMWdZ50dwzhOF3TIDn5MlfUdXwaS3r5KB7jI4r0l0IBTjIaUgXcyRl SUM4IXUpw==; Received: from hch by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1iSxpU-0004vC-5h; Fri, 08 Nov 2019 06:33:08 +0000 Date: Thu, 7 Nov 2019 22:33:08 -0800 From: Christoph Hellwig To: "Joel Fernandes (Google)" Cc: linux-kernel@vger.kernel.org, Nicolas Geoffray , kernel-team@android.com, Andrew Morton , Hugh Dickins , linux-kselftest@vger.kernel.org, linux-mm@kvack.org, Shuah Khan Subject: Re: [PATCH 1/2] memfd: Fix COW issue on MAP_PRIVATE and F_SEAL_FUTURE_WRITE mappings Message-ID: <20191108063308.GB18778@infradead.org> References: <20191107195355.80608-1-joel@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191107195355.80608-1-joel@joelfernandes.org> User-Agent: Mutt/1.12.1 (2019-06-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > - * Since the F_SEAL_FUTURE_WRITE seals allow for a MAP_SHARED > - * read-only mapping, take care to not allow mprotect to revert > - * protections. > + * Since an F_SEAL_FUTURE_WRITE sealed memfd can be mapped as > + * MAP_SHARED and read-only, take care to not allow mprotect to > + * revert protections on such mappings. Do this only for shared > + * mappings. For private mappings, don't need to mask VM_MAYWRITE This adds an > 80 char line.