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 D8196C32771 for ; Fri, 19 Aug 2022 15:49:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350320AbiHSPtn (ORCPT ); Fri, 19 Aug 2022 11:49:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50732 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350145AbiHSPsl (ORCPT ); Fri, 19 Aug 2022 11:48:41 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 77071103C7E; Fri, 19 Aug 2022 08:47:31 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id E39BBB82816; Fri, 19 Aug 2022 15:47:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 39A04C433C1; Fri, 19 Aug 2022 15:47:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660924047; bh=4Cii6FiWkvGzvUOnl0qF3nSi1Xn7Sm7VwPaNTm6Bg2o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0s76CNFsfbO/P+wapXqfARf72w1NgdSieIXLP84XI7TN3zXP+7SigNcBlNiEEaXN0 JiaJ1G06zUK5QTWujMRy2R68hQYT72I3YVr9RhZn7W2CFW8eQfr1ZyTluP3QQV+2Ne O24G/HOZK016th2mS7qpOoY+WfdGUa8Kgk/po708= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jann Horn , Oleksij Rempel , Lukas Wunner , Oliver Neukum , Jakub Kicinski Subject: [PATCH 5.10 037/545] usbnet: Fix linkwatch use-after-free on disconnect Date: Fri, 19 Aug 2022 17:36:47 +0200 Message-Id: <20220819153830.887145762@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819153829.135562864@linuxfoundation.org> References: <20220819153829.135562864@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lukas Wunner commit a69e617e533edddf3fa3123149900f36e0a6dc74 upstream. usbnet uses the work usbnet_deferred_kevent() to perform tasks which may sleep. On disconnect, completion of the work was originally awaited in ->ndo_stop(). But in 2003, that was moved to ->disconnect() by historic commit "[PATCH] USB: usbnet, prevent exotic rtnl deadlock": https://git.kernel.org/tglx/history/c/0f138bbfd83c The change was made because back then, the kernel's workqueue implementation did not allow waiting for a single work. One had to wait for completion of *all* work by calling flush_scheduled_work(), and that could deadlock when waiting for usbnet_deferred_kevent() with rtnl_mutex held in ->ndo_stop(). The commit solved one problem but created another: It causes a use-after-free in USB Ethernet drivers aqc111.c, asix_devices.c, ax88179_178a.c, ch9200.c and smsc75xx.c: * If the drivers receive a link change interrupt immediately before disconnect, they raise EVENT_LINK_RESET in their (non-sleepable) ->status() callback and schedule usbnet_deferred_kevent(). * usbnet_deferred_kevent() invokes the driver's ->link_reset() callback, which calls netif_carrier_{on,off}(). * That in turn schedules the work linkwatch_event(). Because usbnet_deferred_kevent() is awaited after unregister_netdev(), netif_carrier_{on,off}() may operate on an unregistered netdev and linkwatch_event() may run after free_netdev(), causing a use-after-free. In 2010, usbnet was changed to only wait for a single instance of usbnet_deferred_kevent() instead of *all* work by commit 23f333a2bfaf ("drivers/net: don't use flush_scheduled_work()"). Unfortunately the commit neglected to move the wait back to ->ndo_stop(). Rectify that omission at long last. Reported-by: Jann Horn Link: https://lore.kernel.org/netdev/CAG48ez0MHBbENX5gCdHAUXZ7h7s20LnepBF-pa5M=7Bi-jZrEA@mail.gmail.com/ Reported-by: Oleksij Rempel Link: https://lore.kernel.org/netdev/20220315113841.GA22337@pengutronix.de/ Signed-off-by: Lukas Wunner Cc: stable@vger.kernel.org Acked-by: Oliver Neukum Link: https://lore.kernel.org/r/d1c87ebe9fc502bffcd1576e238d685ad08321e4.1655987888.git.lukas@wunner.de Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/usb/usbnet.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -830,13 +830,11 @@ int usbnet_stop (struct net_device *net) mpn = !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags); - /* deferred work (task, timer, softirq) must also stop. - * can't flush_scheduled_work() until we drop rtnl (later), - * else workers could deadlock; so make workers a NOP. - */ + /* deferred work (timer, softirq, task) must also stop */ dev->flags = 0; del_timer_sync (&dev->delay); tasklet_kill (&dev->bh); + cancel_work_sync(&dev->kevent); if (!pm) usb_autopm_put_interface(dev->intf); @@ -1585,8 +1583,6 @@ void usbnet_disconnect (struct usb_inter net = dev->net; unregister_netdev (net); - cancel_work_sync(&dev->kevent); - usb_scuttle_anchored_urbs(&dev->deferred); if (dev->driver_info->unbind)