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[23.128.96.18]) by mx.google.com with ESMTP id k5si1337587ejj.483.2021.03.05.05.32.39; Fri, 05 Mar 2021 05:33:02 -0800 (PST) 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 S230300AbhCENaX (ORCPT + 99 others); Fri, 5 Mar 2021 08:30:23 -0500 Received: from mail-oi1-f173.google.com ([209.85.167.173]:43002 "EHLO mail-oi1-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229688AbhCENaT (ORCPT ); Fri, 5 Mar 2021 08:30:19 -0500 Received: by mail-oi1-f173.google.com with SMTP id l64so2469006oig.9; Fri, 05 Mar 2021 05:30:19 -0800 (PST) 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=8NQ7Or3v5+8GN49zjQ5rWQuRInRqmqpTTu5Y5nSeheE=; b=ppsr0ZvsQQ797ApnVAhlIQ5nPBwlP/yx3Wd7ABdjd/Six4Q4oj39wwJzOMi2jmQOnA BVy56ipH2hTPtXn569W6xCMTOFEE6AWSApzhuUjww/IbT3G9SO5dqeTxAKxOX/ESc+4Q FSYjbSX/anBtLnV4Dzo+RIEHCyMyAg5cwZvVi6V56iV240JFw/ZhFxAMWm7ErwcvU1iE j6g7Wrcb5XCtp+8nRJNddsxQoVFq2o7n4vYX+fCNFoJvXzG8/W8Up37aaKHdxkMf+diw d5UEKhXKiZApa+5p/elSeJWFwfYhUC9XqWSVNlisPwlJGyb1PwrjUr9Rzsc4ztW70F9R VR0Q== X-Gm-Message-State: AOAM531JKYHL7zCQHS3htckd423QtYq/geHtgU4YRZzFVTGKUXP3EBFN COD/QuFZiBXVtxbfbzgaDgCPjfgLodLL6OQpF4Q= X-Received: by 2002:aca:e189:: with SMTP id y131mr7198566oig.71.1614951019003; Fri, 05 Mar 2021 05:30:19 -0800 (PST) MIME-Version: 1.0 References: <1614802160-29362-1-git-send-email-george.kennedy@oracle.com> <9c3bc1b2-bb8d-194d-6faf-e4d7d346dc9b@oracle.com> In-Reply-To: <9c3bc1b2-bb8d-194d-6faf-e4d7d346dc9b@oracle.com> From: "Rafael J. Wysocki" Date: Fri, 5 Mar 2021 14:30:07 +0100 Message-ID: Subject: Re: [PATCH 1/1] ACPI: fix acpi table use after free To: George Kennedy , David Hildenbrand Cc: "Rafael J. Wysocki" , Robert Moore , Erik Kaneda , Rafael Wysocki , Len Brown , ACPI Devel Maling List , "open list:ACPI COMPONENT ARCHITECTURE (ACPICA)" , Linux Kernel Mailing List , Mike Rapoport , 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 Fri, Mar 5, 2021 at 12:14 AM George Kennedy wrote: > > Hello Rafael, > > On 3/4/2021 7:14 AM, Rafael J. Wysocki wrote: > > On Thu, Mar 4, 2021 at 2:22 AM George Kennedy wrote: > >> Since commit 7fef431be9c9 ("mm/page_alloc: place pages to tail > >> in __free_pages_core()") the following use after free occurs > >> intermittently when acpi tables are accessed. > >> > >> BUG: KASAN: use-after-free in ibft_init+0x134/0xc49 > >> Read of size 4 at addr ffff8880be453004 by task swapper/0/1 > >> CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.12.0-rc1-7a7fd0d #1 > >> Call Trace: > >> dump_stack+0xf6/0x158 > >> print_address_description.constprop.9+0x41/0x60 > >> kasan_report.cold.14+0x7b/0xd4 > >> __asan_report_load_n_noabort+0xf/0x20 > >> ibft_init+0x134/0xc49 > >> do_one_initcall+0xc4/0x3e0 > >> kernel_init_freeable+0x5af/0x66b > >> kernel_init+0x16/0x1d0 > >> ret_from_fork+0x22/0x30 > >> > >> ACPI tables mapped via kmap() do not have their mapped pages > >> reserved and the pages can be "stolen" by the buddy allocator. > >> > > What do you mean by this? >> > The ibft table, for example, is mapped in via acpi_map() and kmap(). The > page for the ibft table is not reserved, so it can end up on the freelist. You appear to be saying that it is not sufficient to kmap() a page in order to use it safely. It is also necessary to reserve it upfront, for example with the help of memblock_reserve(). Is that correct? If so, is there an alternative way to reserve a page frame? > > > >> Use memblock_reserve() to reserve all the ACPI table pages. > > How is this going to help? > If the ibft table page is not reserved, it will end up on the freelist > and potentially be allocated before ibft_init() is called. > > I believe this is the call that causes the ibft table page (in this case > pfn=0xbe453) to end up on the freelist: > > memmap_init_range: size=bd49b, nid=0, zone=1, start_pfn=1000, > zone_end_pfn=100000 David, is commit 7fef431be9c9 related to this and if so, then how? > [ 0.477319] memmap_init_range+0x33b/0x4e2 > [ 0.479053] memmap_init_zone+0x1e0/0x243 > [ 0.485276] free_area_init_node+0xa4e/0xac5 > [ 0.498242] free_area_init+0xf4a/0x107a > [ 0.509958] zone_sizes_init+0xd9/0x111 > [ 0.511731] paging_init+0x4a/0x4c > [ 0.512417] setup_arch+0x14f8/0x1758 > [ 0.519193] start_kernel+0x6c/0x46f > [ 0.519921] x86_64_start_reservations+0x37/0x39 > [ 0.520847] x86_64_start_kernel+0x7b/0x7e > [ 0.521666] secondary_startup_64_no_verify+0xb0/0xbb > > > > >> Signed-off-by: George Kennedy > >> --- > >> arch/x86/kernel/setup.c | 3 +-- > >> drivers/acpi/acpica/tbinstal.c | 4 ++++ > >> 2 files changed, 5 insertions(+), 2 deletions(-) > >> > >> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > >> index d883176..97deea3 100644 > >> --- a/arch/x86/kernel/setup.c > >> +++ b/arch/x86/kernel/setup.c > >> @@ -1046,6 +1046,7 @@ void __init setup_arch(char **cmdline_p) > >> cleanup_highmap(); > >> > >> memblock_set_current_limit(ISA_END_ADDRESS); > >> + acpi_boot_table_init(); > > This cannot be moved before the acpi_table_upgrade() invocation AFAICS. > > > > Why exactly do you want to move it? > > Want to make sure there are slots for memblock_reserve() to be able to > reserve the page. Well, that may not require reordering the initialization this way. > >> e820__memblock_setup(); > >> > >> /* > >> @@ -1139,8 +1140,6 @@ void __init setup_arch(char **cmdline_p) > >> /* > >> * Parse the ACPI tables for possible boot-time SMP configuration. > >> */ > >> - acpi_boot_table_init(); > >> - > >> early_acpi_boot_init(); > >> > >> initmem_init(); > >> diff --git a/drivers/acpi/acpica/tbinstal.c b/drivers/acpi/acpica/tbinstal.c > >> index 8d1e5b5..4e32b22 100644 > >> --- a/drivers/acpi/acpica/tbinstal.c > >> +++ b/drivers/acpi/acpica/tbinstal.c > >> @@ -8,6 +8,7 @@ > >> *****************************************************************************/ > >> > >> #include > >> +#include > >> #include "accommon.h" > >> #include "actables.h" > >> > >> @@ -58,6 +59,9 @@ > >> new_table_desc->flags, > >> new_table_desc->pointer); > >> > >> + memblock_reserve(new_table_desc->address, > >> + PAGE_ALIGN(new_table_desc->pointer->length)); > >> + > > Why do you want to do this here in the first place? > > If there is a better place to do it, I can move the memblock_reserve() > there. The memblock_reserve() cannot be done from the ibft code - it's > too late - the ibft table page has already ended up on the freelist by > the time ibft_init() is called. I see. > > > > Things like that cannot be done in the ACPICA code in general. > > Can you recommend a better place to do the memblock_reserve() from? Maybe. I need to understand the problem better, though. Thanks!