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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 78B74C352A3 for ; Mon, 10 Feb 2020 13:32:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 493B820714 for ; Mon, 10 Feb 2020 13:32:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581341529; bh=+Gs1qpGHwY/YA1ef7rvdKTeYTUgNheFOCtYxDH9e/w8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=vATl2mNXEFl/ebVdxEPvXuw08599MWp5ssYu+vwoWIyML8a/Ipovo9L+KsL5UfDs0 4jzkXVSQ+clj6EE5ngVqQa887cDKVLw+2LuESi5BunUdBm5DC51jtkw5qEGWDgjbzj c3S+V6tabqCEQwUlsPw8mI5y0b2Zzb4JCasACbuE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731253AbgBJNcC (ORCPT ); Mon, 10 Feb 2020 08:32:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:53642 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728162AbgBJMfy (ORCPT ); Mon, 10 Feb 2020 07:35:54 -0500 Received: from localhost (unknown [209.37.97.194]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C96F7215A4; Mon, 10 Feb 2020 12:35:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581338153; bh=+Gs1qpGHwY/YA1ef7rvdKTeYTUgNheFOCtYxDH9e/w8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TL6oAaQN/IJsd7RLXWOIpjQ4bbxZw7lMNJD8gVFFT3GLY8XOSPeNCxqhaoxeCeiMt O+LsDJX5yIiSmKneXQljD/gbTRuBrd/IYWjyEG+nkEq1dWhwtzqkH4oem4fZviBdzR wtxGH/W4qNzJ7yJG6wN/Xzz4bt1SNxvbGlvuU3RY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vladis Dronov , Guenter Roeck , Wim Van Sebroeck Subject: [PATCH 4.19 119/195] watchdog: fix UAF in reboot notifier handling in watchdog core code Date: Mon, 10 Feb 2020 04:32:57 -0800 Message-Id: <20200210122316.997761733@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200210122305.731206734@linuxfoundation.org> References: <20200210122305.731206734@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Vladis Dronov commit 69503e585192fdd84b240f18a0873d20e18a2e0a upstream. After the commit 44ea39420fc9 ("drivers/watchdog: make use of devm_register_reboot_notifier()") the struct notifier_block reboot_nb in the struct watchdog_device is removed from the reboot notifiers chain at the time watchdog's chardev is closed. But at least in i6300esb.c case reboot_nb is embedded in the struct esb_dev which can be freed on its device removal and before the chardev is closed, thus UAF at reboot: [ 7.728581] esb_probe: esb_dev.watchdog_device ffff91316f91ab28 ts# uname -r note the address ^^^ 5.5.0-rc5-ae6088-wdog ts# ./openwdog0 & [1] 696 ts# opened /dev/watchdog0, sleeping 10s... ts# echo 1 > /sys/devices/pci0000\:00/0000\:00\:09.0/remove [ 178.086079] devres:rel_nodes: dev ffff91317668a0b0 data ffff91316f91ab28 esb_dev.watchdog_device.reboot_nb memory is freed here ^^^ ts# ...woken up [ 181.459010] devres:rel_nodes: dev ffff913171781000 data ffff913174a1dae8 [ 181.460195] devm_unreg_reboot_notifier: res ffff913174a1dae8 nb ffff91316f91ab78 attempt to use memory already freed ^^^ [ 181.461063] devm_unreg_reboot_notifier: nb->call 6b6b6b6b6b6b6b6b [ 181.461243] devm_unreg_reboot_notifier: nb->next 6b6b6b6b6b6b6b6b freed memory is filled with a slub poison ^^^ [1]+ Done ./openwdog0 ts# reboot [ 229.921862] systemd-shutdown[1]: Rebooting. [ 229.939265] notifier_call_chain: nb ffffffff9c6c2f20 nb->next ffffffff9c6d50c0 [ 229.943080] notifier_call_chain: nb ffffffff9c6d50c0 nb->next 6b6b6b6b6b6b6b6b [ 229.946054] notifier_call_chain: nb 6b6b6b6b6b6b6b6b INVAL [ 229.957584] general protection fault: 0000 [#1] SMP [ 229.958770] CPU: 0 PID: 1 Comm: systemd-shutdow Not tainted 5.5.0-rc5-ae6088-wdog [ 229.960224] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), ... [ 229.963288] RIP: 0010:notifier_call_chain+0x66/0xd0 [ 229.969082] RSP: 0018:ffffb20dc0013d88 EFLAGS: 00010246 [ 229.970812] RAX: 000000000000002e RBX: 6b6b6b6b6b6b6b6b RCX: 00000000000008b3 [ 229.972929] RDX: 0000000000000000 RSI: 0000000000000096 RDI: ffffffff9ccc46ac [ 229.975028] RBP: 0000000000000001 R08: 0000000000000000 R09: 00000000000008b3 [ 229.977039] R10: 0000000000000001 R11: ffffffff9c26c740 R12: 0000000000000000 [ 229.979155] R13: 6b6b6b6b6b6b6b6b R14: 0000000000000000 R15: 00000000fffffffa ... slub_debug=FZP poison ^^^ [ 229.989089] Call Trace: [ 229.990157] blocking_notifier_call_chain+0x43/0x59 [ 229.991401] kernel_restart_prepare+0x14/0x30 [ 229.992607] kernel_restart+0x9/0x30 [ 229.993800] __do_sys_reboot+0x1d2/0x210 [ 230.000149] do_syscall_64+0x3d/0x130 [ 230.001277] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 230.002639] RIP: 0033:0x7f5461bdd177 [ 230.016402] Modules linked in: i6300esb [ 230.050261] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b Fix the crash by reverting 44ea39420fc9 so unregister_reboot_notifier() is called when watchdog device is removed. This also makes handling of the reboot notifier unified with the handling of the restart handler, which is freed with unregister_restart_handler() in the same place. Fixes: 44ea39420fc9 ("drivers/watchdog: make use of devm_register_reboot_notifier()") Cc: stable@vger.kernel.org # v4.15+ Signed-off-by: Vladis Dronov Reviewed-by: Guenter Roeck Link: https://lore.kernel.org/r/20200108125347.6067-1-vdronov@redhat.com Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck Signed-off-by: Greg Kroah-Hartman --- drivers/watchdog/watchdog_core.c | 35 +++++++++++++++++++++++++++++++++++ drivers/watchdog/watchdog_dev.c | 36 +----------------------------------- 2 files changed, 36 insertions(+), 35 deletions(-) --- a/drivers/watchdog/watchdog_core.c +++ b/drivers/watchdog/watchdog_core.c @@ -138,6 +138,25 @@ int watchdog_init_timeout(struct watchdo } EXPORT_SYMBOL_GPL(watchdog_init_timeout); +static int watchdog_reboot_notifier(struct notifier_block *nb, + unsigned long code, void *data) +{ + struct watchdog_device *wdd; + + wdd = container_of(nb, struct watchdog_device, reboot_nb); + if (code == SYS_DOWN || code == SYS_HALT) { + if (watchdog_active(wdd)) { + int ret; + + ret = wdd->ops->stop(wdd); + if (ret) + return NOTIFY_BAD; + } + } + + return NOTIFY_DONE; +} + static int watchdog_restart_notifier(struct notifier_block *nb, unsigned long action, void *data) { @@ -226,6 +245,19 @@ static int __watchdog_register_device(st } } + if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) { + wdd->reboot_nb.notifier_call = watchdog_reboot_notifier; + + ret = register_reboot_notifier(&wdd->reboot_nb); + if (ret) { + pr_err("watchdog%d: Cannot register reboot notifier (%d)\n", + wdd->id, ret); + watchdog_dev_unregister(wdd); + ida_simple_remove(&watchdog_ida, id); + return ret; + } + } + if (wdd->ops->restart) { wdd->restart_nb.notifier_call = watchdog_restart_notifier; @@ -271,6 +303,9 @@ static void __watchdog_unregister_device if (wdd->ops->restart) unregister_restart_handler(&wdd->restart_nb); + if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) + unregister_reboot_notifier(&wdd->reboot_nb); + watchdog_dev_unregister(wdd); ida_simple_remove(&watchdog_ida, wdd->id); } --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -42,7 +42,6 @@ #include /* For handling misc devices */ #include /* For module stuff/... */ #include /* For mutexes */ -#include /* For reboot notifier */ #include /* For memory functions */ #include /* For standard types (like size_t) */ #include /* For watchdog specific items */ @@ -1048,25 +1047,6 @@ static void watchdog_cdev_unregister(str put_device(&wd_data->dev); } -static int watchdog_reboot_notifier(struct notifier_block *nb, - unsigned long code, void *data) -{ - struct watchdog_device *wdd; - - wdd = container_of(nb, struct watchdog_device, reboot_nb); - if (code == SYS_DOWN || code == SYS_HALT) { - if (watchdog_active(wdd)) { - int ret; - - ret = wdd->ops->stop(wdd); - if (ret) - return NOTIFY_BAD; - } - } - - return NOTIFY_DONE; -} - /* * watchdog_dev_register: register a watchdog device * @wdd: watchdog device @@ -1085,22 +1065,8 @@ int watchdog_dev_register(struct watchdo return ret; ret = watchdog_register_pretimeout(wdd); - if (ret) { + if (ret) watchdog_cdev_unregister(wdd); - return ret; - } - - if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) { - wdd->reboot_nb.notifier_call = watchdog_reboot_notifier; - - ret = devm_register_reboot_notifier(&wdd->wd_data->dev, - &wdd->reboot_nb); - if (ret) { - pr_err("watchdog%d: Cannot register reboot notifier (%d)\n", - wdd->id, ret); - watchdog_dev_unregister(wdd); - } - } return ret; }