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=-9.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 1BBE8C12002 for ; Wed, 21 Jul 2021 18:26:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E84CA61208 for ; Wed, 21 Jul 2021 18:26:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238230AbhGURpt (ORCPT ); Wed, 21 Jul 2021 13:45:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:34458 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235826AbhGURpr (ORCPT ); Wed, 21 Jul 2021 13:45:47 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C4D3F61222; Wed, 21 Jul 2021 18:26:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626891984; bh=jkc6omrR2hOV0Md2ueLa6a5u2LaKn/ysa9NV7K55nyI=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=UKZqTckGSywksr+buTJ+HyKoeBGkMbSFGr4E9NFmjFFQDrM8YbC0n9Ft6BUUBKwvp UUhborSDC3cFqq+OmULJkl66FoRyPFjhruH90Ob++dwJUUjDYczG0UvMJai1IgYRAO qertKc+qHF9TODKojtQAdMgg7zq5S+J6blkP/Z+ZGuWb+mpNtyvgazRAX6BOtgNz83 9VV5yDAlvRqNarkvY8eF+uyTrW55vlYb04jCT9TdBAjvf77O4Bu6z4MeMljDU25gee laSU5iBV076VyDYmpDxofxkGT1lyXq06gLUyKOWZi/LiUTweuecDKjBOCwOApMhIa2 P7mcAPozmLugQ== Date: Wed, 21 Jul 2021 20:26:20 +0200 (CEST) From: Jiri Kosina To: Lin Ma , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz cc: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Two issues caused by commit e305509e678b3 ("Bluetooth: use correct lock to prevent UAF of hdev object") In-Reply-To: Message-ID: References: User-Agent: Alpine 2.21 (LSU 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 13 Jul 2021, Jiri Kosina wrote: > Hi, > > commit e305509e678b3 ("Bluetooth: use correct lock to prevent UAF of hdev > object") has two issues, and I believe it should be reverted for 5.14 > final. Could you please elaborate what is the exact UAF scenario the patch > is fixing? It's rather hard to deduce from the very short changelog, but > it's pretty obvious that it creates at least two issues. Marcel, Johan, Luiz, any thoughts on this please? Thanks. > > > > (1) it introduces a possibility of deadlock between hci_sock_dev_event() > and hci_sock_sendmsg(). > > Namely: > > - hci_sock_sendmsg(HCI_CHANNEL_LOGGING) acquires lock_sock(sk) and then > calls into hci_logging_frame() -> hci_send_to_channel() which in turn > acquires hci_sk_list.lock > > - after the mentioned commit, hci_sock_dev_event() first acquires > hci_sk_list.lock before doing lock_sock(sk) on each of the sockets it > iterates through, creating the reverse dependency > > > Please find the full lockdep report below for reference. > > (2) it causes sleeping function to be called from atomic context, because > it's not allowed to sleep after acquiring read_lock(), which is exactly > what this patch does (lock_sock() is sleepable). Report below as well. > > > > > > > BUG: sleeping function called from invalid context at net/core/sock.c:3100 > in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 448, name: kworker/0:5 > 6 locks held by kworker/0:5/448: > #0: ffff89e947fb4338 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x1c2/0x5e0 > #1: ffffadef40973e78 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x1c2/0x5e0 > #2: ffff89e946998a20 (&dev->mutex){....}-{3:3}, at: hub_event+0x6a/0xd50 [usbcore] > #3: ffff89e950828a20 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0x54/0x270 [usbcore] > #4: ffff89e9504e71a8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0x1a/0x1d0 > #5: ffffffffc117a3c0 (hci_sk_list.lock){++++}-{2:2}, at: hci_sock_dev_event+0x12b/0x1e0 [bluetooth] > CPU: 0 PID: 448 Comm: kworker/0:5 Not tainted 5.14.0-rc1-00003-g7fef2edf7cc7 #15 > Hardware name: LENOVO 20K5S22R00/20K5S22R00, BIOS R0IET38W (1.16 ) 05/31/2017 > Workqueue: usb_hub_wq hub_event [usbcore] > Call Trace: > dump_stack_lvl+0x56/0x6c > ___might_sleep+0x1b6/0x210 > lock_sock_nested+0x29/0xa0 > hci_sock_dev_event+0x156/0x1e0 [bluetooth] > hci_unregister_dev+0xd2/0x350 [bluetooth] > btusb_disconnect+0x63/0x150 [btusb] > usb_unbind_interface+0x79/0x260 [usbcore] > device_release_driver_internal+0xf7/0x1d0 > bus_remove_device+0xef/0x160 > device_del+0x1ac/0x430 > ? usb_remove_ep_devs+0x1b/0x30 [usbcore] > usb_disable_device+0x8d/0x1a0 [usbcore] > usb_disconnect+0xc1/0x270 [usbcore] > ? hub_event+0x4b0/0xd50 [usbcore] > hub_port_connect+0x82/0xa20 [usbcore] > ? __mutex_unlock_slowpath+0x43/0x2b0 > hub_event+0x4c4/0xd50 [usbcore] > ? lock_is_held_type+0xb4/0x120 > process_one_work+0x244/0x5e0 > worker_thread+0x3c/0x390 > ? process_one_work+0x5e0/0x5e0 > kthread+0x133/0x160 > ? set_kthread_struct+0x40/0x40 > ret_from_fork+0x22/0x30 > > ====================================================== > WARNING: possible circular locking dependency detected > 5.14.0-rc1-00003-g7fef2edf7cc7 #15 Tainted: G W > ------------------------------------------------------ > kworker/0:5/448 is trying to acquire lock: > ffff89e950647920 (sk_lock-AF_BLUETOOTH-BTPROTO_HCI){+.+.}-{0:0}, at: hci_sock_dev_event+0x156/0x1e0 [bluetooth] > > but task is already holding lock: > ffffffffc117a3c0 (hci_sk_list.lock){++++}-{2:2}, at: hci_sock_dev_event+0x12b/0x1e0 [bluetooth] > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #1 (hci_sk_list.lock){++++}-{2:2}: > _raw_read_lock+0x38/0x70 > systemd-sysv-generator[1254]: stat() failed on /etc/init.d/jexec, ignoring: No such file or directory > hci_send_to_channel+0x22/0x50 [bluetooth] > hci_sock_sendmsg+0xa2b/0xa40 [bluetooth] > sock_sendmsg+0x5b/0x60 > ____sys_sendmsg+0x1ed/0x250 > systemd-sysv-generator[1254]: SysV service '/etc/init.d/tpfand' lacks a native systemd unit file. Automatically generating a unit file for compatibility. Please update package to include a native systemd unit file, in order to make it more safe and robust. > ___sys_sendmsg+0x88/0xd0 > __sys_sendmsg+0x5e/0xa0 > do_syscall_64+0x3a/0xb0 > systemd-sysv-generator[1254]: SysV service '/etc/init.d/boot.local' lacks a native systemd unit file. Automatically generating a unit file for compatibility. Please update package to include a native systemd unit file, in order to make it more safe and robust. > entry_SYSCALL_64_after_hwframe+0x44/0xae > > -> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_HCI){+.+.}-{0:0}: > __lock_acquire+0x124a/0x1680 > lock_acquire+0x278/0x300 > lock_sock_nested+0x72/0xa0 > hci_sock_dev_event+0x156/0x1e0 [bluetooth] > hci_unregister_dev+0xd2/0x350 [bluetooth] > btusb_disconnect+0x63/0x150 [btusb] > usb_unbind_interface+0x79/0x260 [usbcore] > device_release_driver_internal+0xf7/0x1d0 > bus_remove_device+0xef/0x160 > device_del+0x1ac/0x430 > usb_disable_device+0x8d/0x1a0 [usbcore] > usb_disconnect+0xc1/0x270 [usbcore] > hub_port_connect+0x82/0xa20 [usbcore] > hub_event+0x4c4/0xd50 [usbcore] > process_one_work+0x244/0x5e0 > worker_thread+0x3c/0x390 > kthread+0x133/0x160 > ret_from_fork+0x22/0x30 > > other info that might help us debug this: > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(hci_sk_list.lock); > lock(sk_lock-AF_BLUETOOTH-BTPROTO_HCI); > lock(hci_sk_list.lock); > lock(sk_lock-AF_BLUETOOTH-BTPROTO_HCI); > > *** DEADLOCK *** > > 6 locks held by kworker/0:5/448: > #0: ffff89e947fb4338 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x1c2/0x5e0 > #1: ffffadef40973e78 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x1c2/0x5e0 > #2: ffff89e946998a20 (&dev->mutex){....}-{3:3}, at: hub_event+0x6a/0xd50 [usbcore] > #3: ffff89e950828a20 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0x54/0x270 [usbcore] > #4: ffff89e9504e71a8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0x1a/0x1d0 > #5: ffffffffc117a3c0 (hci_sk_list.lock){++++}-{2:2}, at: hci_sock_dev_event+0x12b/0x1e0 [bluetooth] > > stack backtrace: > CPU: 0 PID: 448 Comm: kworker/0:5 Tainted: G W 5.14.0-rc1-00003-g7fef2edf7cc7 #15 > Hardware name: LENOVO 20K5S22R00/20K5S22R00, BIOS R0IET38W (1.16 ) 05/31/2017 > Workqueue: usb_hub_wq hub_event [usbcore] > Call Trace: > dump_stack_lvl+0x56/0x6c > check_noncircular+0x105/0x120 > ? stack_trace_save+0x4b/0x70 > ? save_trace+0x3d/0x340 > ? __lock_acquire+0x124a/0x1680 > __lock_acquire+0x124a/0x1680 > lock_acquire+0x278/0x300 > ? hci_sock_dev_event+0x156/0x1e0 [bluetooth] > ? lock_release+0x15a/0x2a0 > lock_sock_nested+0x72/0xa0 > ? hci_sock_dev_event+0x156/0x1e0 [bluetooth] > hci_sock_dev_event+0x156/0x1e0 [bluetooth] > hci_unregister_dev+0xd2/0x350 [bluetooth] > btusb_disconnect+0x63/0x150 [btusb] > usb_unbind_interface+0x79/0x260 [usbcore] > device_release_driver_internal+0xf7/0x1d0 > bus_remove_device+0xef/0x160 > device_del+0x1ac/0x430 > ? usb_remove_ep_devs+0x1b/0x30 [usbcore] > usb_disable_device+0x8d/0x1a0 [usbcore] > usb_disconnect+0xc1/0x270 [usbcore] > ? hub_event+0x4b0/0xd50 [usbcore] > hub_port_connect+0x82/0xa20 [usbcore] > ? __mutex_unlock_slowpath+0x43/0x2b0 > hub_event+0x4c4/0xd50 [usbcore] > ? lock_is_held_type+0xb4/0x120 > process_one_work+0x244/0x5e0 > worker_thread+0x3c/0x390 > ? process_one_work+0x5e0/0x5e0 > kthread+0x133/0x160 > ? set_kthread_struct+0x40/0x40 > ret_from_fork+0x22/0x30 > > > > -- > Jiri Kosina > SUSE Labs > -- Jiri Kosina SUSE Labs