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=BAYES_00,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 782F6C433C1 for ; Mon, 22 Mar 2021 16:58:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4955561998 for ; Mon, 22 Mar 2021 16:58:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230231AbhCVQ6D (ORCPT ); Mon, 22 Mar 2021 12:58:03 -0400 Received: from mail-ot1-f54.google.com ([209.85.210.54]:39487 "EHLO mail-ot1-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231424AbhCVQ5j (ORCPT ); Mon, 22 Mar 2021 12:57:39 -0400 Received: by mail-ot1-f54.google.com with SMTP id h6-20020a0568300346b02901b71a850ab4so16627822ote.6; Mon, 22 Mar 2021 09:57:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=83NWJNS5IfkRY8uZgeuY59TwUa5zRy9EPOl1w3UC3QY=; b=jeT9/RnxEKPb/8yqBTWOfvyrUOHAiba+7bhNXJSGyNjf3iiWXIjMPVW90ZyasJePcG 0ZcNJSBgINnls3qb1VMn0zJu1cCg+GbRRtHRUd63Z+hb2JECGjVKTPrW1nYjnTNmmnao ARXCE03OWRCLQW3oFjvuHpVGOcY9LtIkNlTQlFlDmP545fRM0ATFWZghopNxM3Jxa29H 6+uIQS4mk+jDq3691GEmWM8/W0tcwjZzvYUhowBX6jJ82N5fEmM1XZM6Eq3Fx8L4s6s7 MluTheTbpoJIvWD/l0chs0A6lT98JmpIC/Utphz+KxQWOZKOOo/7O7SqGzMb0I2d31ZB lG6A== X-Gm-Message-State: AOAM530GfOLprk+vE5Uz4EostLRt9YWPcv/+8jEeIauxy86yHw5mi1xb 0cetm6Vgzdx5o24PzwCjiIXIEFEtoJbsTgCvb8Y= X-Google-Smtp-Source: ABdhPJyhnA/+oYMcscd/h9+EcNHB25LvbW75G4JNL2BfBnGBms87P/FZLeg1MsH8Ia7MemQWrMg1KmzgpL8/ti+AZWo= X-Received: by 2002:a05:6830:1e03:: with SMTP id s3mr685011otr.321.1616432258283; Mon, 22 Mar 2021 09:57:38 -0700 (PDT) MIME-Version: 1.0 References: <3236337.DtqTXxM43S@kreacher> In-Reply-To: From: "Rafael J. Wysocki" Date: Mon, 22 Mar 2021 17:57:27 +0100 Message-ID: Subject: Re: [PATCH 1/1] ACPI: fix acpi table use after free To: Mike Rapoport Cc: "Rafael J. Wysocki" , "Rafael J. Wysocki" , Erik Kaneda , David Hildenbrand , George Kennedy , Robert Moore , Rafael Wysocki , Len Brown , ACPI Devel Maling List , "open list:ACPI COMPONENT ARCHITECTURE (ACPICA)" , Linux Kernel Mailing List , Konrad Rzeszutek Wilk , Dan Carpenter , Dhaval Giani , Andrew Morton , Vlastimil Babka , Oscar Salvador , Wei Yang , Pankaj Gupta , Michal Hocko Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Sat, Mar 20, 2021 at 9:25 AM Mike Rapoport wrote: > > On Thu, Mar 18, 2021 at 04:22:37PM +0100, Rafael J. Wysocki wrote: > > On Thu, Mar 18, 2021 at 11:50 AM Rafael J. Wysocki wrote: > > > > > > On Thu, Mar 18, 2021 at 8:25 AM Mike Rapoport wrote: > > > > > > > > On Wed, Mar 17, 2021 at 09:14:37PM +0100, Rafael J. Wysocki wrote: > > > > > On Monday, March 15, 2021 5:19:29 PM CET Rafael J. Wysocki wrote: > > > > > > On Sun, Mar 14, 2021 at 8:00 PM Mike Rapoport wrote: > > > > > > > > > > > > > > On Thu, Mar 11, 2021 at 04:36:31PM +0100, Rafael J. Wysocki wrote: > > > > > > > > On Wed, Mar 10, 2021 at 8:47 PM David Hildenbrand wrote: > > > > > > > > > > > > > > > > > > > > There is some care that should be taken to make sure we get the order > > > > > > > > > > right, but I don't see a fundamental issue here. > > > > > > > > > > > > > > > > Me neither. > > > > > > > > > > > > > > > > > > If I understand correctly, Rafael's concern is about changing the parts of > > > > > > > > > > ACPICA that should be OS agnostic, so I think we just need another place to > > > > > > > > > > call memblock_reserve() rather than acpi_tb_install_table_with_override(). > > > > > > > > > > > > > > > > Something like this. > > > > > > > > > > > > > > > > There is also the problem that memblock_reserve() needs to be called > > > > > > > > for all of the tables early enough, which will require some reordering > > > > > > > > of the early init code. > > > > > > > > > > > > > > > > > > Since the reservation should be done early in x86::setup_arch() (and > > > > > > > > > > probably in arm64::setup_arch()) we might just have a function that parses > > > > > > > > > > table headers and reserves them, similarly to how we parse the tables > > > > > > > > > > during KASLR setup. > > > > > > > > > > > > > > > > Right. > > > > > > > > > > > > > > I've looked at it a bit more and we do something like the patch below that > > > > > > > nearly duplicates acpi_tb_parse_root_table() which is not very nice. > > > > > > > > > > > > It looks to me that the code need not be duplicated (see below). > > > > > > > > > > > > > Besides, reserving ACPI tables early and then calling acpi_table_init() > > > > > > > (and acpi_tb_parse_root_table() again would mean doing the dance with > > > > > > > early_memremap() twice for no good reason. > > > > > > > > > > > > That'd be simply inefficient which is kind of acceptable to me to start with. > > > > > > > > > > > > And I changing the ACPICA code can be avoided at least initially, it > > > > > > by itself would be a good enough reason. > > > > > > > > > > > > > I believe the most effective way to deal with this would be to have a > > > > > > > function that does parsing, reservation and installs the tables supplied by > > > > > > > the firmware which can be called really early and then another function > > > > > > > that overrides tables if needed a some later point. > > > > > > > > > > > > I agree that this should be the direction to go into. > > > > > > > > > > So maybe something like the patch below? > > > > > > > > > > I'm not sure if acpi_boot_table_prepare() gets called early enough, though. > > > > > > > > To be 100% safe it should be called before e820__memblock_setup(). > > > > > > OK > > > > Well, that said, reserve_bios_regions() doesn't seem to have concerns > > like this and I'm not sure why ACPI tables should be reserved before > > this runs. That applies to efi_reserve_boot_services() too. > > > > I can put the new call before e820__memblock_alloc_reserved_mpc_new(), > > but I'm not sure why to put it before efi_reserve_boot_services(), > > say? > > The general idea is to reserve all the memory used by the firmware before > memblock allocations are possible, i.e. before e820__memblock_setup(). > Currently this is not the case, but it does not make it more correct. I see. > Theoretically, it is possible that reserve_bios_regions() will cause a > memory allocation and the allocated memory will be exactly at the area > where ACPI tables reside. > > In practice I believe this is very unlikely, but who knows. > > Another advantage of having ACPI tables handy by the time we do the memory > detection is that we will be able to SRAT earlier and simplify NUMA > initialization. OK, fair enough.