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=-19.0 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=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 DF50DC4345B for ; Mon, 29 Mar 2021 08:54:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C213461A0D for ; Mon, 29 Mar 2021 08:54:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236569AbhC2Ixx (ORCPT ); Mon, 29 Mar 2021 04:53:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:52660 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234256AbhC2Ie5 (ORCPT ); Mon, 29 Mar 2021 04:34:57 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2F8C3619B1; Mon, 29 Mar 2021 08:34:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1617006895; bh=ikM35ZXyxBcvzKVFUCevC1eXLU5FwCni+tC4GjejoD0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L2gGcJkHj3oKQ3mcJkJKBtp9EHlTdXgD8j5L1Oq9xi0Oy7lXf5I0Mx21fAxdNqcLM uPMLl/jk7r7/vmxUNi7WHmXSu7zRfn4pcmvwZbYJUdhpw6ohu+bdgB+iO5JeDr6hSO zBTs1YzcqhOmKMs8oqiHIPzKl4HHn6jOP8HrfK3E= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xie He , "David S. Miller" , Sasha Levin Subject: [PATCH 5.11 142/254] net: hdlc_x25: Prevent racing between "x25_close" and "x25_xmit"/"x25_rx" Date: Mon, 29 Mar 2021 09:57:38 +0200 Message-Id: <20210329075637.879647940@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210329075633.135869143@linuxfoundation.org> References: <20210329075633.135869143@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: Xie He [ Upstream commit bf0ffea336b493c0a8c8bc27b46683ecf1e8f294 ] "x25_close" is called by "hdlc_close" in "hdlc.c", which is called by hardware drivers' "ndo_stop" function. "x25_xmit" is called by "hdlc_start_xmit" in "hdlc.c", which is hardware drivers' "ndo_start_xmit" function. "x25_rx" is called by "hdlc_rcv" in "hdlc.c", which receives HDLC frames from "net/core/dev.c". "x25_close" races with "x25_xmit" and "x25_rx" because their callers race. However, we need to ensure that the LAPB APIs called in "x25_xmit" and "x25_rx" are called before "lapb_unregister" is called in "x25_close". This patch adds locking to ensure when "x25_xmit" and "x25_rx" are doing their work, "lapb_unregister" is not yet called in "x25_close". Reasons for not solving the racing between "x25_close" and "x25_xmit" by calling "netif_tx_disable" in "x25_close": 1. We still need to solve the racing between "x25_close" and "x25_rx"; 2. The design of the HDLC subsystem assumes the HDLC hardware drivers have full control over the TX queue, and the HDLC protocol drivers (like this driver) have no control. Controlling the queue here in the protocol driver may interfere with hardware drivers' control of the queue. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Xie He Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/wan/hdlc_x25.c | 42 +++++++++++++++++++++++++++++++++++++- 1 file changed, 41 insertions(+), 1 deletion(-) diff --git a/drivers/net/wan/hdlc_x25.c b/drivers/net/wan/hdlc_x25.c index 4aaa6388b9ee..5a6a945f6c81 100644 --- a/drivers/net/wan/hdlc_x25.c +++ b/drivers/net/wan/hdlc_x25.c @@ -23,6 +23,8 @@ struct x25_state { x25_hdlc_proto settings; + bool up; + spinlock_t up_lock; /* Protects "up" */ }; static int x25_ioctl(struct net_device *dev, struct ifreq *ifr); @@ -104,6 +106,8 @@ static void x25_data_transmit(struct net_device *dev, struct sk_buff *skb) static netdev_tx_t x25_xmit(struct sk_buff *skb, struct net_device *dev) { + hdlc_device *hdlc = dev_to_hdlc(dev); + struct x25_state *x25st = state(hdlc); int result; /* There should be a pseudo header of 1 byte added by upper layers. @@ -114,11 +118,19 @@ static netdev_tx_t x25_xmit(struct sk_buff *skb, struct net_device *dev) return NETDEV_TX_OK; } + spin_lock_bh(&x25st->up_lock); + if (!x25st->up) { + spin_unlock_bh(&x25st->up_lock); + kfree_skb(skb); + return NETDEV_TX_OK; + } + switch (skb->data[0]) { case X25_IFACE_DATA: /* Data to be transmitted */ skb_pull(skb, 1); if ((result = lapb_data_request(dev, skb)) != LAPB_OK) dev_kfree_skb(skb); + spin_unlock_bh(&x25st->up_lock); return NETDEV_TX_OK; case X25_IFACE_CONNECT: @@ -147,6 +159,7 @@ static netdev_tx_t x25_xmit(struct sk_buff *skb, struct net_device *dev) break; } + spin_unlock_bh(&x25st->up_lock); dev_kfree_skb(skb); return NETDEV_TX_OK; } @@ -164,6 +177,7 @@ static int x25_open(struct net_device *dev) .data_transmit = x25_data_transmit, }; hdlc_device *hdlc = dev_to_hdlc(dev); + struct x25_state *x25st = state(hdlc); struct lapb_parms_struct params; int result; @@ -190,6 +204,10 @@ static int x25_open(struct net_device *dev) if (result != LAPB_OK) return -EINVAL; + spin_lock_bh(&x25st->up_lock); + x25st->up = true; + spin_unlock_bh(&x25st->up_lock); + return 0; } @@ -197,6 +215,13 @@ static int x25_open(struct net_device *dev) static void x25_close(struct net_device *dev) { + hdlc_device *hdlc = dev_to_hdlc(dev); + struct x25_state *x25st = state(hdlc); + + spin_lock_bh(&x25st->up_lock); + x25st->up = false; + spin_unlock_bh(&x25st->up_lock); + lapb_unregister(dev); } @@ -205,15 +230,28 @@ static void x25_close(struct net_device *dev) static int x25_rx(struct sk_buff *skb) { struct net_device *dev = skb->dev; + hdlc_device *hdlc = dev_to_hdlc(dev); + struct x25_state *x25st = state(hdlc); if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) { dev->stats.rx_dropped++; return NET_RX_DROP; } - if (lapb_data_received(dev, skb) == LAPB_OK) + spin_lock_bh(&x25st->up_lock); + if (!x25st->up) { + spin_unlock_bh(&x25st->up_lock); + kfree_skb(skb); + dev->stats.rx_dropped++; + return NET_RX_DROP; + } + + if (lapb_data_received(dev, skb) == LAPB_OK) { + spin_unlock_bh(&x25st->up_lock); return NET_RX_SUCCESS; + } + spin_unlock_bh(&x25st->up_lock); dev->stats.rx_errors++; dev_kfree_skb_any(skb); return NET_RX_DROP; @@ -298,6 +336,8 @@ static int x25_ioctl(struct net_device *dev, struct ifreq *ifr) return result; memcpy(&state(hdlc)->settings, &new_settings, size); + state(hdlc)->up = false; + spin_lock_init(&state(hdlc)->up_lock); /* There's no header_ops so hard_header_len should be 0. */ dev->hard_header_len = 0; -- 2.30.1