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=-4.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 97B91C04EB9 for ; Tue, 4 Dec 2018 01:43:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 567CF2146D for ; Tue, 4 Dec 2018 01:43:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="JSHBn+3u" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 567CF2146D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726007AbeLDBnQ (ORCPT ); Mon, 3 Dec 2018 20:43:16 -0500 Received: from mail-pl1-f196.google.com ([209.85.214.196]:32864 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725915AbeLDBnQ (ORCPT ); Mon, 3 Dec 2018 20:43:16 -0500 Received: by mail-pl1-f196.google.com with SMTP id z23so7432866plo.0; Mon, 03 Dec 2018 17:43:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=Th0v2UT5RVhPgXbxBsglycGhp+RqO4OKzX8UkhGpqp8=; b=JSHBn+3uR4u1ek2VtKdIOtwqbIpsPAjLCdulzxtZsMV27b9uEBrLNgBHSiL9ZhOa+/ WSu5FTgeJTjjRI4tOjLG5RjDIXLVjsiNTqd6gWXTWPrYUcEjkU5YvW1ms4syHYDfKUWy s1cZ1aBeEQRzfDlBhVfuprrOlWyqxQIFbvY/E9JeArVsnFhiI37k6AuA+gNgPq92HUT7 D3WGR0lxS+EbtD0+eW5ZIyL2peZWqZXKm+YDWa/SUZmj7Wjgjzz/l65oUM+IxfCXtgwo hn1jbmlPSUpp1NLqqPrxsOTGRM3VfghyJcSywoMQl6PCCK+KFak+FfX0QSS+qFnIopVJ 4wcQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=Th0v2UT5RVhPgXbxBsglycGhp+RqO4OKzX8UkhGpqp8=; b=F8MC5T6Q52DQ+hRkgI+bJBuBEHmMpKLMGCiJyi3OQNhY/WaNHoukWaZpTEOkBS0I3U 4J5oGl6I0ItGdSqkTItYpxVkAgVdaISwZgs1XJyS774WCzcwn94jZiBApQQ5xLka08aj gXnddmYjHzW3PountGJUrIvmNVZj8jcCHo9XU+qkDCEBWhbmaRYrgTMibuWuDEZ22hCn 3SmHSi84If20r7NNXi2FI5YLgKQvbTaj7lhG73pW9xE1CHcR+s2F+B3v03wBvTYGDUrF L9qlFKWdIX+XNHAvq/GDezFXetjK8YxYXlxLXvSDZnXXxLxyHi80wfgci8PX3qy0I+wT yn1g== X-Gm-Message-State: AA+aEWZd0O+1DCz9jgSO7ksdJLmjkm2zKYUrvjPUSBO+quuhO2kgfo4q TQOaZsFP56lepDAaI1jb5w0= X-Google-Smtp-Source: AFSGD/XcD7IKlkrNaYYS/wvP8i7Fd77/uwZyjxBJfhA69WKv6hB/aQ0fjuuVchNFj9+7btK1KDKKCQ== X-Received: by 2002:a17:902:4324:: with SMTP id i33mr11593800pld.227.1543887794180; Mon, 03 Dec 2018 17:43:14 -0800 (PST) Received: from [10.2.19.70] ([208.91.2.1]) by smtp.gmail.com with ESMTPSA id a4sm16092640pgv.70.2018.12.03.17.43.12 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 03 Dec 2018 17:43:13 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 12.1 \(3445.101.1\)) Subject: Re: [PATCH 1/2] vmalloc: New flag for flush before releasing pages From: Nadav Amit In-Reply-To: <20181128000754.18056-2-rick.p.edgecombe@intel.com> Date: Mon, 3 Dec 2018 17:43:11 -0800 Cc: Andrew Morton , Andy Lutomirski , Will Deacon , linux-mm , LKML , Kernel Hardening , naveen.n.rao@linux.vnet.ibm.com, anil.s.keshavamurthy@intel.com, David Miller , Masami Hiramatsu , Steven Rostedt , Ingo Molnar , ast@kernel.org, Daniel Borkmann , jeyu@kernel.org, netdev@vger.kernel.org, Ard Biesheuvel , Jann Horn , kristen@linux.intel.com, Dave Hansen , deneen.t.dock@intel.com, Peter Zijlstra Content-Transfer-Encoding: quoted-printable Message-Id: <4883FED1-D0EC-41B0-A90F-1A697756D41D@gmail.com> References: <20181128000754.18056-1-rick.p.edgecombe@intel.com> <20181128000754.18056-2-rick.p.edgecombe@intel.com> To: Rick Edgecombe X-Mailer: Apple Mail (2.3445.101.1) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Nov 27, 2018, at 4:07 PM, Rick Edgecombe = wrote: >=20 > Since vfree will lazily flush the TLB, but not lazily free the = underlying pages, > it often leaves stale TLB entries to freed pages that could get = re-used. This is > undesirable for cases where the memory being freed has special = permissions such > as executable. So I am trying to finish my patch-set for preventing transient W+X = mappings from taking space, by handling kprobes & ftrace that I missed (thanks = again for pointing it out). But all of the sudden, I don=E2=80=99t understand why we have the = problem that this (your) patch-set deals with at all. We already change the mappings to = make the memory writable before freeing the memory, so why can=E2=80=99t we = make it non-executable at the same time? Actually, why do we make the module = memory, including its data executable before freeing it??? In other words: disable_ro_nx() is called by free_module() before = freeing the memory. Wouldn=E2=80=99t inverting the logic makes much more sense? = I am confused. -- >8 -- From: Nadav Amit Subject: [PATCH] modules: disable_ro_nx() should enable nx=20 --- kernel/module.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 7cb207249437..e12d760ea3b0 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2029,14 +2029,13 @@ void set_all_modules_text_ro(void) =20 static void disable_ro_nx(const struct module_layout *layout) { + frob_text(layout, set_memory_nx); + if (rodata_enabled) { frob_text(layout, set_memory_rw); frob_rodata(layout, set_memory_rw); frob_ro_after_init(layout, set_memory_rw); } - frob_rodata(layout, set_memory_x); - frob_ro_after_init(layout, set_memory_x); - frob_writable_data(layout, set_memory_x); } =20 #else --=20 2.17.1