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=-5.7 required=3.0 tests=DATE_IN_PAST_03_06, 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=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 ABE42C2D0DB for ; Wed, 22 Jan 2020 13:24:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 82DF22468C for ; Wed, 22 Jan 2020 13:24:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579699496; bh=AXzGzg7aB76QJhArJB3cCflXRp9u84Qf07aZ4biO7Uk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=d8PNhLFe2DpMzrqaMhd9XqKx5LPZTWIBbvLYrCRPfSi0wujcb23qh2c9mVnH28kTI 4tl558dLFGdtDs3v6+UqCfsN7bEBspB6A0VbtwLqeM14EoIpCvH4ccpB7pqdoa1Z2Y yJB21EHkdOb1T5f3ygMQx3m+Kd1xFV1zbTRQZASs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730492AbgAVNYw (ORCPT ); Wed, 22 Jan 2020 08:24:52 -0500 Received: from mail.kernel.org ([198.145.29.99]:44074 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730109AbgAVNYs (ORCPT ); Wed, 22 Jan 2020 08:24:48 -0500 Received: from localhost (unknown [84.241.205.26]) (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 9A23424688; Wed, 22 Jan 2020 13:24:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579699487; bh=AXzGzg7aB76QJhArJB3cCflXRp9u84Qf07aZ4biO7Uk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0jgSovNa2tRsD9uXPWp068r8BRPKqgMGKf1rHY8lCLyLEyvqcKudnYa0KRpd6fBbA 6JvJ4wnVk0ik68Jk3rQx7enW/d364Vmsfkbe2wCE7Yr5+1Yli3sba6dABkRbze3FE9 gyAO4TLUKySzsbktuAqe3hrWdHPQ0wiSVkswEeAE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ido Schimmel , Shalom Toledo , Jiri Pirko , "David S. Miller" Subject: [PATCH 5.4 161/222] mlxsw: spectrum: Do not modify cloned SKBs during xmit Date: Wed, 22 Jan 2020 10:29:07 +0100 Message-Id: <20200122092845.242283226@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200122092833.339495161@linuxfoundation.org> References: <20200122092833.339495161@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ido Schimmel commit 2da51ce75d86ab1f7770ac1391a9a1697ddaa60c upstream. The driver needs to prepend a Tx header to each packet it is transmitting. The header includes information such as the egress port and traffic class. The addition of the header requires the driver to modify the SKB's header and therefore it must not be shared. Otherwise, we risk hitting various race conditions. For example, when a packet is flooded (cloned) by the bridge driver to two switch ports swp1 and swp2: t0 - mlxsw_sp_port_xmit() is called for swp1. Tx header is prepended with swp1's port number t1 - mlxsw_sp_port_xmit() is called for swp2. Tx header is prepended with swp2's port number, overwriting swp1's port number t2 - The device processes data buffer from t0. Packet is transmitted via swp2 t3 - The device processes data buffer from t1. Packet is transmitted via swp2 Usually, the device is fast enough and transmits the packet before its Tx header is overwritten, but this is not the case in emulated environments. Fix this by making sure the SKB's header is writable by calling skb_cow_head(). Since the function ensures we have headroom to push the Tx header, the check further in the function can be removed. v2: * Use skb_cow_head() instead of skb_unshare() as suggested by Jakub * Remove unnecessary check regarding headroom Fixes: 56ade8fe3fe1 ("mlxsw: spectrum: Add initial support for Spectrum ASIC") Signed-off-by: Ido Schimmel Reported-by: Shalom Toledo Acked-by: Jiri Pirko Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/mellanox/mlxsw/spectrum.c | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c @@ -812,23 +812,17 @@ static netdev_tx_t mlxsw_sp_port_xmit(st u64 len; int err; + if (skb_cow_head(skb, MLXSW_TXHDR_LEN)) { + this_cpu_inc(mlxsw_sp_port->pcpu_stats->tx_dropped); + dev_kfree_skb_any(skb); + return NETDEV_TX_OK; + } + memset(skb->cb, 0, sizeof(struct mlxsw_skb_cb)); if (mlxsw_core_skb_transmit_busy(mlxsw_sp->core, &tx_info)) return NETDEV_TX_BUSY; - if (unlikely(skb_headroom(skb) < MLXSW_TXHDR_LEN)) { - struct sk_buff *skb_orig = skb; - - skb = skb_realloc_headroom(skb, MLXSW_TXHDR_LEN); - if (!skb) { - this_cpu_inc(mlxsw_sp_port->pcpu_stats->tx_dropped); - dev_kfree_skb_any(skb_orig); - return NETDEV_TX_OK; - } - dev_consume_skb_any(skb_orig); - } - if (eth_skb_pad(skb)) { this_cpu_inc(mlxsw_sp_port->pcpu_stats->tx_dropped); return NETDEV_TX_OK;