From patchwork Sat Jan 11 10:34:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiongfeng Wang X-Patchwork-Id: 11328809 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6C856921 for ; Sat, 11 Jan 2020 10:39:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4198D2146E for ; Sat, 11 Jan 2020 10:39:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728996AbgAKKjw (ORCPT ); Sat, 11 Jan 2020 05:39:52 -0500 Received: from szxga07-in.huawei.com ([45.249.212.35]:33940 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728861AbgAKKjw (ORCPT ); Sat, 11 Jan 2020 05:39:52 -0500 Received: from DGGEMS406-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id C400EEAAEB4F45AE65C4; Sat, 11 Jan 2020 18:39:49 +0800 (CST) Received: from linux-ibm.site (10.175.102.37) by DGGEMS406-HUB.china.huawei.com (10.3.19.206) with Microsoft SMTP Server id 14.3.439.0; Sat, 11 Jan 2020 18:39:41 +0800 From: Xiongfeng Wang To: , , , , CC: , , , , , Subject: [PATCH] PCI/AER: increments pci bus reference count in aer-inject process Date: Sat, 11 Jan 2020 18:34:59 +0800 Message-ID: <1578738899-11408-1-git-send-email-wangxiongfeng2@huawei.com> X-Mailer: git-send-email 1.7.12.4 MIME-Version: 1.0 X-Originating-IP: [10.175.102.37] X-CFilter-Loop: Reflected Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org When I test 'aer-inject' with the following procedures: 1. inject a fatal error into a PCI device 2. remove the parent device by sysfs 3. execute command 'rmmod aer-inject' I came across the following use-after-free. [ 297.581524] ================================================================== [ 297.581543] BUG: KASAN: use-after-free in pci_bus_set_ops+0xb4/0xb8 [ 297.581545] Read of size 8 at addr ffff802edbde80e0 by task rmmod/21839 [ 297.581552] CPU: 119 PID: 21839 Comm: rmmod Kdump: loaded Not tainted 4.19.36 #1 [ 297.581554] Hardware name: Huawei TaiShan 2280 V2/BC82AMDD, BIOS 1.05 09/18/2019 [ 297.581556] Call trace: [ 297.581561] dump_backtrace+0x0/0x360 [ 297.581563] show_stack+0x24/0x30 [ 297.581569] dump_stack+0xd8/0x104 [ 297.581576] print_address_description+0x68/0x278 [ 297.581578] kasan_report+0x204/0x330 [ 297.581580] __asan_report_load8_noabort+0x30/0x40 [ 297.581582] pci_bus_set_ops+0xb4/0xb8 [ 297.581591] aer_inject_exit+0x198/0x334 [aer_inject] [ 297.581595] __arm64_sys_delete_module+0x310/0x490 [ 297.581601] el0_svc_common+0xfc/0x278 [ 297.581603] el0_svc_handler+0x50/0xc0 [ 297.581605] el0_svc+0x8/0xc [ 297.581608] Allocated by task 1: [ 297.581611] kasan_kmalloc+0xe0/0x190 [ 297.581614] kmem_cache_alloc_trace+0x104/0x218 [ 297.581616] pci_alloc_bus+0x50/0x2e0 [ 297.581618] pci_add_new_bus+0xa8/0xe08 [ 297.581620] pci_scan_bridge_extend+0x884/0xb28 [ 297.581623] pci_scan_child_bus_extend+0x350/0x628 [ 297.581625] pci_scan_child_bus+0x24/0x30 [ 297.581627] pci_scan_bridge_extend+0x3b8/0xb28 [ 297.581629] pci_scan_child_bus_extend+0x350/0x628 [ 297.581631] pci_scan_child_bus+0x24/0x30 [ 297.581635] acpi_pci_root_create+0x558/0x888 [ 297.581640] pci_acpi_scan_root+0x198/0x330 [ 297.581641] acpi_pci_root_add+0x7bc/0xbb0 [ 297.581646] acpi_bus_attach+0x2f4/0x728 [ 297.581647] acpi_bus_attach+0x1b0/0x728 [ 297.581649] acpi_bus_attach+0x1b0/0x728 [ 297.581651] acpi_bus_scan+0xa0/0x110 [ 297.581657] acpi_scan_init+0x20c/0x500 [ 297.581659] acpi_init+0x54c/0x5d4 [ 297.581661] do_one_initcall+0xbc/0x480 [ 297.581665] kernel_init_freeable+0x5fc/0x6ac [ 297.581670] kernel_init+0x18/0x128 [ 297.581671] ret_from_fork+0x10/0x18 [ 297.581673] Freed by task 19270: [ 297.581675] __kasan_slab_free+0x120/0x228 [ 297.581677] kasan_slab_free+0x10/0x18 [ 297.581678] kfree+0x80/0x1f8 [ 297.581680] release_pcibus_dev+0x54/0x68 [ 297.581686] device_release+0xd4/0x1c0 [ 297.581689] kobject_put+0x12c/0x400 [ 297.581691] device_unregister+0x30/0xc0 [ 297.581693] pci_remove_bus+0xe8/0x1c0 [ 297.581695] pci_remove_bus_device+0xd0/0x2f0 [ 297.581697] pci_stop_and_remove_bus_device_locked+0x2c/0x40 [ 297.581701] remove_store+0x1b8/0x1d0 [ 297.581703] dev_attr_store+0x60/0x80 [ 297.581708] sysfs_kf_write+0x104/0x170 [ 297.581710] kernfs_fop_write+0x23c/0x430 [ 297.581713] __vfs_write+0xec/0x4e0 [ 297.581714] vfs_write+0x12c/0x3d0 [ 297.581715] ksys_write+0xd0/0x190 [ 297.581716] __arm64_sys_write+0x70/0xa0 [ 297.581718] el0_svc_common+0xfc/0x278 [ 297.581720] el0_svc_handler+0x50/0xc0 [ 297.581721] el0_svc+0x8/0xc [ 297.581724] The buggy address belongs to the object at ffff802edbde8000 which belongs to the cache kmalloc-2048 of size 2048 [ 297.581726] The buggy address is located 224 bytes inside of 2048-byte region [ffff802edbde8000, ffff802edbde8800) [ 297.581727] The buggy address belongs to the page: [ 297.581730] page:ffff7e00bb6f7a00 count:1 mapcount:0 mapping:ffff8026de810780 index:0x0 compound_mapcount: 0 [ 297.591520] flags: 0x2ffffe0000008100(slab|head) [ 297.596121] raw: 2ffffe0000008100 ffff7e00bb6f5008 ffff7e00bb6ff608 ffff8026de810780 [ 297.596123] raw: 0000000000000000 00000000000f000f 00000001ffffffff 0000000000000000 [ 297.596124] page dumped because: kasan: bad access detected [ 297.596126] Memory state around the buggy address: [ 297.596128] ffff802edbde7f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 297.596129] ffff802edbde8000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 297.596131] >ffff802edbde8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 297.596132] ^ [ 297.596133] ffff802edbde8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 297.596135] ffff802edbde8180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 297.596135] ================================================================== It is because when we unload the module and restore the member 'pci_ops' of 'pci_bus', the 'pci_bus' has been freed. This patch increments the reference count of 'pci_bus' when we modify its member 'pci_ops' and decrements the reference count after we have restored its member. This patch export pci_bus_get() and pci_bus_put() again and reverts the following two commits. fae6b93b19b4 ("PCI: Unexport pci_bus_get() and pci_bus_put()") ecd29c1a38af ("PCI: Make pci_bus_get(), pci_bus_put() private") Signed-off-by: Xiongfeng Wang --- drivers/pci/bus.c | 2 ++ drivers/pci/pci.h | 2 -- drivers/pci/pcie/aer_inject.c | 8 ++++++++ include/linux/pci.h | 2 ++ 4 files changed, 12 insertions(+), 2 deletions(-) diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c index 8e40b3e..495059d 100644 --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -417,9 +417,11 @@ struct pci_bus *pci_bus_get(struct pci_bus *bus) get_device(&bus->dev); return bus; } +EXPORT_SYMBOL(pci_bus_get); void pci_bus_put(struct pci_bus *bus) { if (bus) put_device(&bus->dev); } +EXPORT_SYMBOL(pci_bus_put); diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index a0a53bd..cf849b7 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -286,8 +286,6 @@ void __pci_bus_assign_resources(const struct pci_bus *bus, void pci_reassigndev_resource_alignment(struct pci_dev *dev); void pci_disable_bridge_window(struct pci_dev *dev); -struct pci_bus *pci_bus_get(struct pci_bus *bus); -void pci_bus_put(struct pci_bus *bus); /* PCIe link information */ #define PCIE_SPEED2STR(speed) \ diff --git a/drivers/pci/pcie/aer_inject.c b/drivers/pci/pcie/aer_inject.c index 6988fe7..0b6b3d0 100644 --- a/drivers/pci/pcie/aer_inject.c +++ b/drivers/pci/pcie/aer_inject.c @@ -307,6 +307,13 @@ static int pci_bus_set_aer_ops(struct pci_bus *bus) spin_lock_irqsave(&inject_lock, flags); if (ops == &aer_inj_pci_ops) goto out; + /* + * increments the reference count of the pci bus. Otherwise, when we + * restore the 'pci_ops' in 'aer_inject_exit', the 'pci_bus' may have + * been freed. + */ + pci_bus_get(bus); + pci_bus_ops_init(bus_ops, bus, ops); list_add(&bus_ops->list, &pci_bus_ops_list); bus_ops = NULL; @@ -529,6 +536,7 @@ static void __exit aer_inject_exit(void) while ((bus_ops = pci_bus_ops_pop())) { pci_bus_set_ops(bus_ops->bus, bus_ops->ops); + pci_bus_put(bus_ops->bus); kfree(bus_ops); } diff --git a/include/linux/pci.h b/include/linux/pci.h index c393dff..adef0da 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1288,6 +1288,8 @@ int pci_add_ext_cap_save_buffer(struct pci_dev *dev, void pci_release_selected_regions(struct pci_dev *, int); /* drivers/pci/bus.c */ +struct pci_bus *pci_bus_get(struct pci_bus *bus); +void pci_bus_put(struct pci_bus *bus); void pci_add_resource(struct list_head *resources, struct resource *res); void pci_add_resource_offset(struct list_head *resources, struct resource *res, resource_size_t offset);