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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B69CDC74A5B for ; Wed, 29 Mar 2023 16:13:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229488AbjC2QNz (ORCPT ); Wed, 29 Mar 2023 12:13:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56658 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229456AbjC2QNy (ORCPT ); Wed, 29 Mar 2023 12:13:54 -0400 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9D4E84C19; Wed, 29 Mar 2023 09:13:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1680106403; x=1711642403; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=IcZUGqXQdbaUhmOWfiLm0nqOnBoxUV2KhfPp/FBCDQY=; b=E0pfP9dkMP32xOi+waujr8AuEJkEH0+MacJHKc5a6ENU8g+lb2L1u8Pb zA4aFZZMnDXAmKkgVhBQNKHK6Id21K+nDOPMeX6KyG1zU2cIHT0/UWVHk p1PbFEL+tfctaM7Q6DkLaqc1Jvnp+fVuPW6LN7NE9GNEOZYBAGKvMY4MS 2fR+h7sj0/zCOtqh8S2X6q6LX6u7WCYU3XrBjWYFoDYr+2gcKyRIQae3J 7ir5F4JF7n9YtukYpm4AVwS3BkeFOsK3w7ZaI1KyrO6R0t7x7LrEMiyYY 0dO69yOV0ahRt4jf1oPrHGgiNqc7vJniHfJIN3svlddiulvc0Dnq6F5vZ w==; X-IronPort-AV: E=McAfee;i="6600,9927,10664"; a="368694489" X-IronPort-AV: E=Sophos;i="5.98,301,1673942400"; d="scan'208";a="368694489" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Mar 2023 09:04:15 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10664"; a="808285617" X-IronPort-AV: E=Sophos;i="5.98,301,1673942400"; d="scan'208";a="808285617" Received: from tinabao-mobl1.amr.corp.intel.com (HELO [10.209.80.72]) ([10.209.80.72]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Mar 2023 09:04:14 -0700 Message-ID: Date: Wed, 29 Mar 2023 09:04:13 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.9.0 Subject: Re: [PATCH] PCI: Fix use-after-free in pci_bus_release_domain_nr() Content-Language: en-US To: Rob Herring Cc: Bjorn Helgaas , =?UTF-8?Q?Pali_Roh=c3=a1r?= , Jon Hunter , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org References: <20230329123835.2724518-1-robh@kernel.org> From: Sathyanarayanan Kuppuswamy In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 3/29/23 8:59 AM, Rob Herring wrote: > On Wed, Mar 29, 2023 at 10:13 AM Sathyanarayanan Kuppuswamy > wrote: >> >> >> >> On 3/29/23 5:38 AM, Rob Herring wrote: >>> Commit c14f7ccc9f5d ("PCI: Assign PCI domain IDs by ida_alloc()") >>> introduced a use-after-free bug in the bus removal cleanup. The issue >>> was found with kfence: >>> >>> [ 19.285870] ================================================================== >>> [ 19.293351] BUG: KFENCE: use-after-free read in pci_bus_release_domain_nr+0x10/0x70 >>> >>> [ 19.302817] Use-after-free read at 0x000000007f3b80eb (in kfence-#115): >>> [ 19.309677] pci_bus_release_domain_nr+0x10/0x70 >>> [ 19.309691] dw_pcie_host_deinit+0x28/0x78 >>> [ 19.309702] tegra_pcie_deinit_controller+0x1c/0x38 [pcie_tegra194] >>> [ 19.309734] tegra_pcie_dw_probe+0x648/0xb28 [pcie_tegra194] >>> [ 19.309752] platform_probe+0x90/0xd8 >>> [ 19.309764] really_probe+0xb8/0x298 >>> [ 19.309777] __driver_probe_device+0x78/0xd8 >>> [ 19.309788] driver_probe_device+0x38/0x120 >>> [ 19.309799] __device_attach_driver+0x94/0xe0 >>> [ 19.309812] bus_for_each_drv+0x70/0xc8 >>> [ 19.309822] __device_attach+0xfc/0x188 >>> [ 19.309833] device_initial_probe+0x10/0x18 >>> [ 19.309844] bus_probe_device+0x94/0xa0 >>> [ 19.309854] deferred_probe_work_func+0x80/0xb8 >>> [ 19.309864] process_one_work+0x1e0/0x348 >>> [ 19.309882] worker_thread+0x48/0x410 >>> [ 19.309891] kthread+0xf4/0x110 >>> [ 19.309904] ret_from_fork+0x10/0x20 >>> >>> [ 19.311457] kfence-#115: 0x00000000063a155a-0x00000000ba698da8, size=1072, cache=kmalloc-2k >>> >>> [ 19.311469] allocated by task 96 on cpu 10 at 19.279323s: >>> [ 19.311562] __kmem_cache_alloc_node+0x260/0x278 >>> [ 19.311571] kmalloc_trace+0x24/0x30 >>> [ 19.311580] pci_alloc_bus+0x24/0xa0 >>> [ 19.311590] pci_register_host_bridge+0x48/0x4b8 >>> [ 19.311601] pci_scan_root_bus_bridge+0xc0/0xe8 >>> [ 19.311613] pci_host_probe+0x18/0xc0 >>> [ 19.311623] dw_pcie_host_init+0x2c0/0x568 >>> [ 19.311630] tegra_pcie_dw_probe+0x610/0xb28 [pcie_tegra194] >>> [ 19.311647] platform_probe+0x90/0xd8 >>> [ 19.311653] really_probe+0xb8/0x298 >>> [ 19.311663] __driver_probe_device+0x78/0xd8 >>> [ 19.311672] driver_probe_device+0x38/0x120 >>> [ 19.311682] __device_attach_driver+0x94/0xe0 >>> [ 19.311694] bus_for_each_drv+0x70/0xc8 >>> [ 19.311702] __device_attach+0xfc/0x188 >>> [ 19.311713] device_initial_probe+0x10/0x18 >>> [ 19.311724] bus_probe_device+0x94/0xa0 >>> [ 19.311733] deferred_probe_work_func+0x80/0xb8 >>> [ 19.311743] process_one_work+0x1e0/0x348 >>> [ 19.311753] worker_thread+0x48/0x410 >>> [ 19.311763] kthread+0xf4/0x110 >>> [ 19.311771] ret_from_fork+0x10/0x20 >>> >>> [ 19.311782] freed by task 96 on cpu 10 at 19.285833s: >>> [ 19.311799] release_pcibus_dev+0x30/0x40 >>> [ 19.311808] device_release+0x30/0x90 >>> [ 19.311814] kobject_put+0xa8/0x120 >>> [ 19.311832] device_unregister+0x20/0x30 >>> [ 19.311839] pci_remove_bus+0x78/0x88 >>> [ 19.311850] pci_remove_root_bus+0x5c/0x98 >>> [ 19.311860] dw_pcie_host_deinit+0x28/0x78 >>> [ 19.311866] tegra_pcie_deinit_controller+0x1c/0x38 [pcie_tegra194] >>> [ 19.311883] tegra_pcie_dw_probe+0x648/0xb28 [pcie_tegra194] >>> [ 19.311900] platform_probe+0x90/0xd8 >>> [ 19.311906] really_probe+0xb8/0x298 >>> [ 19.311916] __driver_probe_device+0x78/0xd8 >>> [ 19.311926] driver_probe_device+0x38/0x120 >>> [ 19.311936] __device_attach_driver+0x94/0xe0 >>> [ 19.311947] bus_for_each_drv+0x70/0xc8 >>> [ 19.311956] __device_attach+0xfc/0x188 >>> [ 19.311966] device_initial_probe+0x10/0x18 >>> [ 19.311976] bus_probe_device+0x94/0xa0 >>> [ 19.311985] deferred_probe_work_func+0x80/0xb8 >>> [ 19.311995] process_one_work+0x1e0/0x348 >>> [ 19.312005] worker_thread+0x48/0x410 >>> [ 19.312014] kthread+0xf4/0x110 >>> [ 19.312022] ret_from_fork+0x10/0x20 >>> >>> [ 19.313579] CPU: 10 PID: 96 Comm: kworker/u24:2 Not tainted 6.2.0 #4 >>> [ 19.320171] Hardware name: /, BIOS 1.0-d7fb19b 08/10/2022 >>> [ 19.325852] Workqueue: events_unbound deferred_probe_work_func >>> [ 19.331919] ================================================================== >>> >>> The stack trace is a bit misleading as dw_pcie_host_deinit() doesn't >>> directly call pci_bus_release_domain_nr(). The issue turns out to be in >>> pci_remove_root_bus() which first calls pci_remove_bus() which frees the >>> struct pci_bus when its struct device is released. Then >>> pci_bus_release_domain_nr() is called and accesses the freed >>> struct pci_bus. Reordering these fixes the issue. >> >> Since time log is not useful, remove it and just add stack trace. > > Actually, it was useful. It told me that the use-after-free happened > pretty much right after the free. > > Bjorn likes to edit commit messages so I'll leave it up to him to > leave or change. > >> Change looks good to me. But I am not sure whether pci_remove_bus() >> directly frees struct pci_bus or just removes the bus resources? > > struct pci_bus embeds a struct device. The struct device is put which > causes the free of the struct pci_bus. So indirect in that the > refcounting triggers the free, but direct in that pci_remove_bus() > causes it. Got it. Reviewed-by: Kuppuswamy Sathyanarayanan > > Rob -- Sathyanarayanan Kuppuswamy Linux Kernel Developer