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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 C07A5C8301D for ; Tue, 27 Oct 2020 15:58:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 95AD820678 for ; Tue, 27 Oct 2020 15:58:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603814329; bh=lMBRtfN+x0fEfJw097aAfZfK9fpuRHja5PaQFINeo9w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=UTEMPlBbNPqKkwFNAErSCFNwd5+ala0U5objEHZWlsas1owk3vFWgO/VVIWGoWdBv 6EVzjov1N8vnCVng8fGs5KeRYo0gJTfSPvdmnq9eRat/nQNphn30NJnNBIcI6DBmDd 8jJrbLkf6zlJH1wgQhGVRjma69ClYwgoDIKQCqgY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1799418AbgJ0P5Z (ORCPT ); Tue, 27 Oct 2020 11:57:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:56486 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1796483AbgJ0PS6 (ORCPT ); Tue, 27 Oct 2020 11:18:58 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 1ABE920657; Tue, 27 Oct 2020 15:18:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603811937; bh=lMBRtfN+x0fEfJw097aAfZfK9fpuRHja5PaQFINeo9w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AvRi4nKuXwXxzP1HXZ+bqSAYjGnmSXqBAaN97xahmcsRqxUpjcno7Zj2sOhnIxB6q bjxhv59jjXRWV+uU71tOh2Tb+veQgZoroUSjBT17B9Yd44Tz6LRrfwIfsFNbuqBUkQ x6yBezKhowxOiFCBCKBhvvKT99WrnzI1FnrnmH2s= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Christian Eggers , Florian Fainelli , Vladimir Oltean , Jakub Kicinski Subject: [PATCH 5.9 008/757] net: dsa: microchip: fix race condition Date: Tue, 27 Oct 2020 14:44:18 +0100 Message-Id: <20201027135450.919986318@linuxfoundation.org> X-Mailer: git-send-email 2.29.1 In-Reply-To: <20201027135450.497324313@linuxfoundation.org> References: <20201027135450.497324313@linuxfoundation.org> User-Agent: quilt/0.66 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: Christian Eggers [ Upstream commit 8098bd69bc4e925070313b1b95d03510f4f24738 ] Between queuing the delayed work and finishing the setup of the dsa ports, the process may sleep in request_module() (via phy_device_create()) and the queued work may be executed prior to the switch net devices being registered. In ksz_mib_read_work(), a NULL dereference will happen within netof_carrier_ok(dp->slave). Not queuing the delayed work in ksz_init_mib_timer() makes things even worse because the work will now be queued for immediate execution (instead of 2000 ms) in ksz_mac_link_down() via dsa_port_link_register_of(). Call tree: ksz9477_i2c_probe() \--ksz9477_switch_register() \--ksz_switch_register() +--dsa_register_switch() | \--dsa_switch_probe() | \--dsa_tree_setup() | \--dsa_tree_setup_switches() | +--dsa_switch_setup() | | +--ksz9477_setup() | | | \--ksz_init_mib_timer() | | | |--/* Start the timer 2 seconds later. */ | | | \--schedule_delayed_work(&dev->mib_read, msecs_to_jiffies(2000)); | | \--__mdiobus_register() | | \--mdiobus_scan() | | \--get_phy_device() | | +--get_phy_id() | | \--phy_device_create() | | |--/* sleeping, ksz_mib_read_work() can be called meanwhile */ | | \--request_module() | | | \--dsa_port_setup() | +--/* Called for non-CPU ports */ | +--dsa_slave_create() | | +--/* Too late, ksz_mib_read_work() may be called beforehand */ | | \--port->slave = ... | ... | +--Called for CPU port */ | \--dsa_port_link_register_of() | \--ksz_mac_link_down() | +--/* mib_read must be initialized here */ | +--/* work is already scheduled, so it will be executed after 2000 ms */ | \--schedule_delayed_work(&dev->mib_read, 0); \-- /* here port->slave is setup properly, scheduling the delayed work should be safe */ Solution: 1. Do not queue (only initialize) delayed work in ksz_init_mib_timer(). 2. Only queue delayed work in ksz_mac_link_down() if init is completed. 3. Queue work once in ksz_switch_register(), after dsa_register_switch() has completed. Fixes: 7c6ff470aa86 ("net: dsa: microchip: add MIB counter reading support") Signed-off-by: Christian Eggers Reviewed-by: Florian Fainelli Reviewed-by: Vladimir Oltean Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/dsa/microchip/ksz_common.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) --- a/drivers/net/dsa/microchip/ksz_common.c +++ b/drivers/net/dsa/microchip/ksz_common.c @@ -103,14 +103,8 @@ void ksz_init_mib_timer(struct ksz_devic INIT_DELAYED_WORK(&dev->mib_read, ksz_mib_read_work); - /* Read MIB counters every 30 seconds to avoid overflow. */ - dev->mib_read_interval = msecs_to_jiffies(30000); - for (i = 0; i < dev->mib_port_cnt; i++) dev->dev_ops->port_init_cnt(dev, i); - - /* Start the timer 2 seconds later. */ - schedule_delayed_work(&dev->mib_read, msecs_to_jiffies(2000)); } EXPORT_SYMBOL_GPL(ksz_init_mib_timer); @@ -143,7 +137,9 @@ void ksz_mac_link_down(struct dsa_switch /* Read all MIB counters when the link is going down. */ p->read = true; - schedule_delayed_work(&dev->mib_read, 0); + /* timer started */ + if (dev->mib_read_interval) + schedule_delayed_work(&dev->mib_read, 0); } EXPORT_SYMBOL_GPL(ksz_mac_link_down); @@ -450,6 +446,12 @@ int ksz_switch_register(struct ksz_devic return ret; } + /* Read MIB counters every 30 seconds to avoid overflow. */ + dev->mib_read_interval = msecs_to_jiffies(30000); + + /* Start the MIB timer. */ + schedule_delayed_work(&dev->mib_read, 0); + return 0; } EXPORT_SYMBOL(ksz_switch_register);