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=-5.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 CC81CC43467 for ; Thu, 8 Oct 2020 11:04:31 +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 58730215A4 for ; Thu, 8 Oct 2020 11:04:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="OBfb8w1y" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 58730215A4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com 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=jJh/r961JAoZe31vhkOrR3tY1NDnJ70q7I2iR7si4v4=; b=OBfb8w1ympRdFfhUCAFOVPsG7 R4uGuSL/CybFWLVxgH/0/Vd1rlOg/BV5pV782UCYu/0L6yCrcZD/bT1C9z8baCA3yCgE2/dNazUp8 gzzMnbMI9Ze3aOwVP1lCNqtMjpKmTPgRX1CfPkU4KTcEqkhV1k15xPSjD+gizVL4MMdltpRtKHySg Lv2yMQbyjQzSTuygHvVTtAQj1yzLpXDhQk9PJeP4WTI9cA5Dd41lNoDtsT1qCZugt3yIhyaEmETjX ArZI9hR3u00rhqvnf/e2ak5U3WU2DsH093DRv8Z4Nw1nQUeRX/sMSh800JVHniHA/psTL+gFl7GGw /lXRbIKYg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kQThd-0007CS-D5; Thu, 08 Oct 2020 11:03:17 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kQTha-0007Aw-SX for linux-arm-kernel@lists.infradead.org; Thu, 08 Oct 2020 11:03:16 +0000 Received: from gaia (unknown [95.149.105.49]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C9362215A4; Thu, 8 Oct 2020 11:03:10 +0000 (UTC) Date: Thu, 8 Oct 2020 12:03:07 +0100 From: Catalin Marinas To: Michael Ellerman Subject: Re: [PATCH 1/2] mm/mprotect: Call arch_validate_prot under mmap_lock and with length Message-ID: <20201008110307.GH7661@gaia> References: <20201007073932.865218-1-jannh@google.com> <20201007123544.GA11433@infradead.org> <87o8ld0zwt.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <87o8ld0zwt.fsf@mpe.ellerman.id.au> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201008_070315_153221_BD6FE475 X-CRM114-Status: GOOD ( 18.38 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Dave Kleikamp , Will Deacon , Jann Horn , Benjamin Herrenschmidt , kernel list , Christoph Hellwig , Linux-MM , Khalid Aziz , Paul Mackerras , sparclinux@vger.kernel.org, Anthony Yznaga , Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S. Miller" , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Oct 08, 2020 at 09:34:26PM +1100, Michael Ellerman wrote: > Jann Horn writes: > > So while the mprotect() case > > checks the flags and refuses unknown values, the mmap() code just lets > > the architecture figure out which bits are actually valid to set (via > > arch_calc_vm_prot_bits()) and silently ignores the rest? > > > > And powerpc apparently decided that they do want to error out on bogus > > prot values passed to their version of mmap(), and in exchange, assume > > in arch_calc_vm_prot_bits() that the protection bits are valid? > > I don't think we really decided that, it just happened by accident and > no one noticed/complained. > > Seems userspace is pretty well behaved when it comes to passing prot > values to mmap(). It's not necessarily about well behaved but whether it can have security implications. On arm64, if the underlying memory does not support MTE (say some DAX mmap) but we still allow PROT_MTE driven by user, it will lead to an SError which brings the whole machine down. Not sure whether ADI has similar requirements but at least for arm64 we addressed the mmap() case as well (see my other email on the details; I think the approach would work on SPARC as well). -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel