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=-5.3 required=3.0 tests=BAYES_00,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 34CBFC433E0 for ; Tue, 11 Aug 2020 21:29:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0845A206DA for ; Tue, 11 Aug 2020 21:29:21 +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="qdgp2xuI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726576AbgHKV3U (ORCPT ); Tue, 11 Aug 2020 17:29:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726115AbgHKV3U (ORCPT ); Tue, 11 Aug 2020 17:29:20 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 10761C06174A for ; Tue, 11 Aug 2020 14:29:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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; bh=wxZR/gjBlYyvU4B4UnrTgxXpJrJ5D0dMaAco8Bf6D5c=; b=qdgp2xuIWZv6AnTssXB0ZewXqP 8t3QxINokttEb6CyQ0ibx5nix9zdlZ1/ZWDH2UgNsgGvr5wJgJQ52mPFFObMJh8STosWe9717j06d sNHFB2zKO+VzBFKzMuB4nY2wf9VLPkaCaiJUPG2m4Q5vrlWQWzeo+7MILDGcf9rN4NSP2BGDJoSB7 LZLaT3kyyGSG9TUMVOc6giGtiJJE1fxkzbLc5Lh4YVWZITEc4BhcSD3IInzAINKNkasDZGw/fCYsY cV1SP1XJDHI0vKyg/GCcj6CoajiHauM1VZxBn6g2GV2uJsu1eo3CmyOATzB+5dw3sQs0EcAo9o1lg wuBivVog==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1k5bpX-0008T1-EM; Tue, 11 Aug 2020 21:29:11 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 88ACC980C68; Tue, 11 Aug 2020 23:29:08 +0200 (CEST) Date: Tue, 11 Aug 2020 23:29:08 +0200 From: Peter Zijlstra To: Jessica Yu Cc: Mauro Carvalho Chehab , linux-kernel@vger.kernel.org, Thomas Gleixner , keescook@chromium.org, Josh Poimboeuf , Miroslav Benes , Mark Rutland , Ard Biesheuvel Subject: Re: [PATCH v2] module: Harden STRICT_MODULE_RWX Message-ID: <20200811212908.GB5637@worktop.programming.kicks-ass.net> References: <20200403171303.GK20760@hirez.programming.kicks-ass.net> <20200808101222.5103093e@coco.lan> <20200810092523.GA8612@linux-8ccs> <20200810150647.GB8612@linux-8ccs> <20200811163427.6edbf343@coco.lan> <20200811145524.GE2674@hirez.programming.kicks-ass.net> <20200811172738.2d632a09@coco.lan> <20200811160134.GA13652@linux-8ccs> <20200811175912.GF2674@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200811175912.GF2674@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 11, 2020 at 07:59:12PM +0200, peterz@infradead.org wrote: > On Tue, Aug 11, 2020 at 06:01:35PM +0200, Jessica Yu wrote: > > > > > On Tue, Aug 11, 2020 at 04:34:27PM +0200, Mauro Carvalho Chehab wrote: > > > > > [33] .plt PROGBITS 0000000000000340 00035c80 > > > > > 0000000000000001 0000000000000000 WAX 0 0 1 > > > > > [34] .init.plt NOBITS 0000000000000341 00035c81 > > > > > 0000000000000001 0000000000000000 WA 0 0 1 > > > > > [35] .text.ftrace[...] PROGBITS 0000000000000342 00035c81 > > > > > 0000000000000001 0000000000000000 WAX 0 0 1 > > > Interesting, my cross-compiled modules do not have the executable flag - > > > > [38] .plt NOBITS 0000000000000340 00038fc0 > > 0000000000000001 0000000000000000 WA 0 0 1 > > [39] .init.plt NOBITS 0000000000000341 00038fc0 > > 0000000000000001 0000000000000000 WA 0 0 1 > > [40] .text.ftrace_tram NOBITS 0000000000000342 00038fc0 > > 0000000000000001 0000000000000000 WA 0 0 1 > > > I'm a bit confused about what NOLOAD actually implies in this context. From the > > ld documentation - "The `(NOLOAD)' directive will mark a section to not be > > loaded at run time." But these sections are marked SHF_ALLOC and are referenced > > to in the module plt code. Or does it just tell the linker to not initialize it? > > Yeah, that confusion is wide-spread, so much so that bfd-ld and gold, > both in bintils, had different behaviour at some point. > > Anyway, another clue is that your build has all NOBITS, while Mauro's > build has PROGBITS for the broken sections. > > Anyway, my gcc-10.1/binutils-2.34 cross tool chain (from k.org) > generates the same as Jessica's too. I wonder if binutils-2.35 is > wonky... When I use the Debian provided cross compiler which uses: binutils-aarch64-linux-gnu 2.35-1 I do indeed see the same thing Mauro does, which seems to suggest there's something really dodgy with that toolchain. Some tools person should have a look.