From patchwork Thu May 20 09:22:11 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 444127 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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham 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 745B7C433ED for ; Thu, 20 May 2021 10:57:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 50433610CB for ; Thu, 20 May 2021 10:57:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235376AbhETK7A (ORCPT ); Thu, 20 May 2021 06:59:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:53054 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238940AbhETK4t (ORCPT ); Thu, 20 May 2021 06:56:49 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C28BE61CF1; Thu, 20 May 2021 10:01:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621504919; bh=6rdUQUeVTP0airz7hksVZY3ye/GUxnnujGEhtTwlOR8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=p/SoSXcMpVkXp8i3jtSPujKNA66Y8e+mFsxdv9iREeMvN2iHD4GsVgS80fSoJc3Dl Sl1R9PXSiCE44WgBmZczNeyZDhxvPPazI0+oyROBp9lN1CCd0L5ikCRpi5mtd2iiw8 fgwO4fUS4N2Cg7GSI+8k7OhZEBw9/rDA5BBBFiSY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xie He , Martin Schiller , "David S. Miller" , Sasha Levin Subject: [PATCH 4.9 139/240] net: lapbether: Prevent racing when checking whether the netif is running Date: Thu, 20 May 2021 11:22:11 +0200 Message-Id: <20210520092113.314064013@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210520092108.587553970@linuxfoundation.org> References: <20210520092108.587553970@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Xie He [ Upstream commit 5acd0cfbfbb5a688da1bfb1a2152b0c855115a35 ] There are two "netif_running" checks in this driver. One is in "lapbeth_xmit" and the other is in "lapbeth_rcv". They serve to make sure that the LAPB APIs called in these functions are called before "lapb_unregister" is called by the "ndo_stop" function. However, these "netif_running" checks are unreliable, because it's possible that immediately after "netif_running" returns true, "ndo_stop" is called (which causes "lapb_unregister" to be called). This patch adds locking to make sure "lapbeth_xmit" and "lapbeth_rcv" can reliably check and ensure the netif is running while doing their work. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Xie He Acked-by: Martin Schiller Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/wan/lapbether.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-) diff --git a/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c index 666bbacb8cb4..24daa1d0e9c5 100644 --- a/drivers/net/wan/lapbether.c +++ b/drivers/net/wan/lapbether.c @@ -56,6 +56,8 @@ struct lapbethdev { struct list_head node; struct net_device *ethdev; /* link to ethernet device */ struct net_device *axdev; /* lapbeth device (lapb#) */ + bool up; + spinlock_t up_lock; /* Protects "up" */ }; static LIST_HEAD(lapbeth_devices); @@ -103,8 +105,9 @@ static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packe rcu_read_lock(); lapbeth = lapbeth_get_x25_dev(dev); if (!lapbeth) - goto drop_unlock; - if (!netif_running(lapbeth->axdev)) + goto drop_unlock_rcu; + spin_lock_bh(&lapbeth->up_lock); + if (!lapbeth->up) goto drop_unlock; len = skb->data[0] + skb->data[1] * 256; @@ -119,11 +122,14 @@ static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packe goto drop_unlock; } out: + spin_unlock_bh(&lapbeth->up_lock); rcu_read_unlock(); return 0; drop_unlock: kfree_skb(skb); goto out; +drop_unlock_rcu: + rcu_read_unlock(); drop: kfree_skb(skb); return 0; @@ -151,13 +157,11 @@ static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb) static netdev_tx_t lapbeth_xmit(struct sk_buff *skb, struct net_device *dev) { + struct lapbethdev *lapbeth = netdev_priv(dev); int err; - /* - * Just to be *really* sure not to send anything if the interface - * is down, the ethernet device may have gone. - */ - if (!netif_running(dev)) + spin_lock_bh(&lapbeth->up_lock); + if (!lapbeth->up) goto drop; /* There should be a pseudo header of 1 byte added by upper layers. @@ -188,6 +192,7 @@ static netdev_tx_t lapbeth_xmit(struct sk_buff *skb, goto drop; } out: + spin_unlock_bh(&lapbeth->up_lock); return NETDEV_TX_OK; drop: kfree_skb(skb); @@ -279,6 +284,7 @@ static const struct lapb_register_struct lapbeth_callbacks = { */ static int lapbeth_open(struct net_device *dev) { + struct lapbethdev *lapbeth = netdev_priv(dev); int err; if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) { @@ -286,13 +292,22 @@ static int lapbeth_open(struct net_device *dev) return -ENODEV; } + spin_lock_bh(&lapbeth->up_lock); + lapbeth->up = true; + spin_unlock_bh(&lapbeth->up_lock); + return 0; } static int lapbeth_close(struct net_device *dev) { + struct lapbethdev *lapbeth = netdev_priv(dev); int err; + spin_lock_bh(&lapbeth->up_lock); + lapbeth->up = false; + spin_unlock_bh(&lapbeth->up_lock); + if ((err = lapb_unregister(dev)) != LAPB_OK) pr_err("lapb_unregister error: %d\n", err); @@ -350,6 +365,9 @@ static int lapbeth_new_device(struct net_device *dev) dev_hold(dev); lapbeth->ethdev = dev; + lapbeth->up = false; + spin_lock_init(&lapbeth->up_lock); + rc = -EIO; if (register_netdevice(ndev)) goto fail;