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[23.128.96.18]) by mx.google.com with ESMTP id va6si11416924ejb.735.2021.03.15.13.26.52; Mon, 15 Mar 2021 13:27:15 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231727AbhCOSFk (ORCPT + 99 others); Mon, 15 Mar 2021 14:05:40 -0400 Received: from mail-ot1-f48.google.com ([209.85.210.48]:43321 "EHLO mail-ot1-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233487AbhCOSFg (ORCPT ); Mon, 15 Mar 2021 14:05:36 -0400 Received: by mail-ot1-f48.google.com with SMTP id m1so7306362ote.10; Mon, 15 Mar 2021 11:05:36 -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=kYvoa+5VswjFlDSSpBWOO17EI4UbXXlkC2EPDqysY+c=; b=YxOg2N6/m1A7dv6XgcaaHm3ZqWfMrlqkn7NHnn8GU2PcD7cwdJscnLS9st8KLumgoY 4lpKujbyyRVqgBxdCLUIUfPdoOg0FY7vTZSeQ7UE6n0z/XMcw3/2Nz1/zztoEQyKbo3+ 6fKQnOT7uM5rx0Ibtmd6JP3h2AHjb1B3q3aYlhpxcZkFlULVPAr40N1k2tFDVIey96IX YwmGavc6X/98ekhv0txTrnHJHuTaNlj9FVyvzckqhZbnOKOBqx2PP75AE+4pNgW3LWQ3 OrImy8+sSR5yO0/tpxhi10iaqPzaC8NhPxLES4RgsVEI2EoWg6lqF5HCUkVANct4oh0N 24+g== X-Gm-Message-State: AOAM532/Vyf8ya1GQsN0fGlmQkZcrHBJDJAZqfdin6N8IJLGVbxlpAIG iir9i1VawH1kSjvL2fxTIYGMLnpWeeN/s94U7hZSV58c X-Received: by 2002:a9d:3422:: with SMTP id v31mr296092otb.260.1615831535970; Mon, 15 Mar 2021 11:05:35 -0700 (PDT) MIME-Version: 1.0 References: <9c3bc1b2-bb8d-194d-6faf-e4d7d346dc9b@oracle.com> <1ae44491-4404-6873-4ee6-6cf58c1ae6fb@redhat.com> <0d05364c-4881-d78a-9721-bd15f5eb822b@redhat.com> In-Reply-To: From: "Rafael J. Wysocki" Date: Mon, 15 Mar 2021 19:05:24 +0100 Message-ID: Subject: Re: [PATCH 1/1] ACPI: fix acpi table use after free To: "Rafael J. Wysocki" Cc: Mike Rapoport , David Hildenbrand , George Kennedy , Robert Moore , Erik Kaneda , 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-kernel@vger.kernel.org On Mon, Mar 15, 2021 at 5:19 PM 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. > > However, it looks to me that something like the following could be > done to start with: > > (a) Make __acpi_map_table() call memblock_reserve() in addition to > early_memremap(). > > My assumption here is that the memblock_reserve() will simply be > ignored if it is called too late. > > (b) Introduce acpi_reserve_tables() as something like > > void __init acpi_table_reserve(void) > { > acpi_initialize_tables(initial_tables, ACPI_MAX_TABLES, 0); > } > > Because initial_tables is passed to acpi_initialize_tables() above and > allow_resize is 0, the array used by it will simply get overwritten > when acpi_table_init() gets called. > > (c) Make setup_arch() call acpi_table_reserve() like in the original > patch from George. > > Would that work? Well, that doesn't work, so more digging ...