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=-6.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 6A812C4BA21 for ; Wed, 26 Feb 2020 20:33:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2E70C2072D for ; Wed, 26 Feb 2020 20:33:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="Zi27k+mb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727350AbgBZUdR (ORCPT ); Wed, 26 Feb 2020 15:33:17 -0500 Received: from mail26.static.mailgun.info ([104.130.122.26]:30622 "EHLO mail26.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727306AbgBZUdQ (ORCPT ); Wed, 26 Feb 2020 15:33:16 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1582749196; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=P/SSm6c2lM4hXptWOYl4b2omu2FYwZZnWYoPeIC1UlE=; b=Zi27k+mb0HOyLvXyXQEeQWsJHeZ8uOGpPhAzPzABDXeD0GVl0WLMb+XFaLkqX6zsV/2af89d /eFLz8hTsK8M/N+ZeFZ5aaS5eZhIgOcjDvXkaw65s2WRrvvK8wf/a2fib0fZmaiAtoWhpTox orkL8//H3RiH0raAhcwu+/+qZSU= X-Mailgun-Sending-Ip: 104.130.122.26 X-Mailgun-Sid: WyJiZjI2MiIsICJuZXRkZXZAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by mxa.mailgun.org with ESMTP id 5e56d607.7fb606602110-smtp-out-n01; Wed, 26 Feb 2020 20:33:11 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 9462DC4479D; Wed, 26 Feb 2020 20:33:11 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: subashab) by smtp.codeaurora.org (Postfix) with ESMTPSA id BC22FC43383; Wed, 26 Feb 2020 20:33:10 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 26 Feb 2020 13:33:10 -0700 From: subashab@codeaurora.org To: Taehee Yoo Cc: davem@davemloft.net, kuba@kernel.org, stranche@codeaurora.org, netdev@vger.kernel.org Subject: Re: [PATCH net 04/10] net: rmnet: fix suspicious RCU usage In-Reply-To: <20200226174706.5334-1-ap420073@gmail.com> References: <20200226174706.5334-1-ap420073@gmail.com> Message-ID: <473fc49bd479ecfeb92adbd9a26fba2e@codeaurora.org> X-Sender: subashab@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2020-02-26 10:47, Taehee Yoo wrote: > rmnet_get_port() internally calls rcu_dereference_rtnl(), > which checks RTNL. > But rmnet_get_port() could be called by packet path. > The packet path is not protected by RTNL. > So, the suspicious RCU usage problem occurs. > > Test commands: > ip netns add nst > ip link add veth0 type veth peer name veth1 > ip link set veth1 netns nst > ip link add rmnet0 link veth0 type rmnet mux_id 1 > ip netns exec nst ip link add rmnet1 link veth1 type rmnet mux_id 1 > ip netns exec nst ip link set veth1 up > ip netns exec nst ip link set rmnet1 up > ip netns exec nst ip a a 192.168.100.2/24 dev rmnet1 > ip link set veth0 up > ip link set rmnet0 up > ip a a 192.168.100.1/24 dev rmnet0 > ping 192.168.100.2 > > Splat looks like: > [ 339.775811][ T969] ============================= > [ 339.777204][ T969] WARNING: suspicious RCU usage > [ 339.778188][ T969] 5.5.0+ #407 Not tainted > [ 339.779123][ T969] ----------------------------- > [ 339.780100][ T969] > drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c:389 suspicious > rcu_dereference_check() usage! > [ 339.781943][ T969] > [ 339.781943][ T969] other info that might help us debug this: > [ 339.781943][ T969] > [ 339.783475][ T969] > [ 339.783475][ T969] rcu_scheduler_active = 2, debug_locks = 1 > [ 339.784656][ T969] 5 locks held by ping/969: > [ 339.785406][ T969] #0: ffff88804cb897f0 (sk_lock-AF_INET){+.+.}, > at: raw_sendmsg+0xab8/0x2980 > [ 339.786766][ T969] #1: ffffffff92925460 (rcu_read_lock_bh){....}, > at: ip_finish_output2+0x243/0x2150 > [ 339.788308][ T969] #2: ffffffff92925460 (rcu_read_lock_bh){....}, > at: __dev_queue_xmit+0x213/0x2e10 > [ 339.790662][ T969] #3: ffff88805a924158 > (&dev->qdisc_running_key#3){+...}, at: ip_finish_output2+0x714/0x2150 > [ 339.792072][ T969] #4: ffff88805b4fdc98 > (&dev->qdisc_xmit_lock_key#3){+.-.}, at: sch_direct_xmit+0x1e2/0x1020 > [ 339.793445][ T969] > [ 339.793445][ T969] stack backtrace: > [ 339.794691][ T969] CPU: 3 PID: 969 Comm: ping Not tainted 5.5.0+ > #407 > [ 339.795946][ T969] Hardware name: innotek GmbH > VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 > [ 339.797621][ T969] Call Trace: > [ 339.798249][ T969] dump_stack+0x96/0xdb > [ 339.798847][ T969] rmnet_get_port.part.9+0x76/0x80 [rmnet] > [ 339.799583][ T969] rmnet_egress_handler+0x107/0x420 [rmnet] > [ 339.800350][ T969] ? sch_direct_xmit+0x1e2/0x1020 > [ 339.801027][ T969] rmnet_vnd_start_xmit+0x3d/0xa0 [rmnet] > [ 339.801784][ T969] dev_hard_start_xmit+0x160/0x740 > [ 339.802667][ T969] sch_direct_xmit+0x265/0x1020 > [ ... ] > > Fixes: ceed73a2cf4a ("drivers: net: ethernet: qualcomm: rmnet: Initial > implementation") > Signed-off-by: Taehee Yoo > --- > drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c | 13 ++++++------- > drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h | 2 +- > .../net/ethernet/qualcomm/rmnet/rmnet_handlers.c | 4 ++-- > drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c | 2 ++ > 4 files changed, 11 insertions(+), 10 deletions(-) > > diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c > b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c > index 7a7d0f521352..93642cdd3305 100644 > --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c > +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c > @@ -382,11 +382,10 @@ struct rtnl_link_ops rmnet_link_ops __read_mostly > = { > .fill_info = rmnet_fill_info, > }; > > -/* Needs either rcu_read_lock() or rtnl lock */ > -struct rmnet_port *rmnet_get_port(struct net_device *real_dev) > +struct rmnet_port *rmnet_get_port_rcu(struct net_device *real_dev) > { > if (rmnet_is_real_dev_registered(real_dev)) > - return rcu_dereference_rtnl(real_dev->rx_handler_data); > + return rcu_dereference(real_dev->rx_handler_data); > else > return NULL; > } > @@ -412,7 +411,7 @@ int rmnet_add_bridge(struct net_device *rmnet_dev, > struct rmnet_port *port, *slave_port; > int err; > > - port = rmnet_get_port(real_dev); > + port = rmnet_get_port_rtnl(real_dev); > > /* If there is more than one rmnet dev attached, its probably being > * used for muxing. Skip the briding in that case > @@ -427,7 +426,7 @@ int rmnet_add_bridge(struct net_device *rmnet_dev, > if (err) > return -EBUSY; > > - slave_port = rmnet_get_port(slave_dev); > + slave_port = rmnet_get_port_rtnl(slave_dev); > slave_port->rmnet_mode = RMNET_EPMODE_BRIDGE; > slave_port->bridge_ep = real_dev; > > @@ -445,11 +444,11 @@ int rmnet_del_bridge(struct net_device > *rmnet_dev, > struct net_device *real_dev = priv->real_dev; > struct rmnet_port *port, *slave_port; > > - port = rmnet_get_port(real_dev); > + port = rmnet_get_port_rtnl(real_dev); > port->rmnet_mode = RMNET_EPMODE_VND; > port->bridge_ep = NULL; > > - slave_port = rmnet_get_port(slave_dev); > + slave_port = rmnet_get_port_rtnl(slave_dev); > rmnet_unregister_real_device(slave_dev, slave_port); > > netdev_dbg(slave_dev, "removed from rmnet as slave\n"); > diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h > b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h > index cd0a6bcbe74a..0d568dcfd65a 100644 > --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h > +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h > @@ -65,7 +65,7 @@ struct rmnet_priv { > struct rmnet_priv_stats stats; > }; > > -struct rmnet_port *rmnet_get_port(struct net_device *real_dev); > +struct rmnet_port *rmnet_get_port_rcu(struct net_device *real_dev); > struct rmnet_endpoint *rmnet_get_endpoint(struct rmnet_port *port, u8 > mux_id); > int rmnet_add_bridge(struct net_device *rmnet_dev, > struct net_device *slave_dev, > diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c > b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c > index 1b74bc160402..074a8b326c30 100644 > --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c > +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c > @@ -184,7 +184,7 @@ rx_handler_result_t rmnet_rx_handler(struct sk_buff > **pskb) > return RX_HANDLER_PASS; > > dev = skb->dev; > - port = rmnet_get_port(dev); > + port = rmnet_get_port_rcu(dev); > > switch (port->rmnet_mode) { > case RMNET_EPMODE_VND: > @@ -217,7 +217,7 @@ void rmnet_egress_handler(struct sk_buff *skb) > skb->dev = priv->real_dev; > mux_id = priv->mux_id; > > - port = rmnet_get_port(skb->dev); > + port = rmnet_get_port_rcu(skb->dev); > if (!port) > goto drop; > > diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c > b/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c > index 509dfc895a33..a26e76e9d382 100644 > --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c > +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c > @@ -50,7 +50,9 @@ static netdev_tx_t rmnet_vnd_start_xmit(struct > sk_buff *skb, > > priv = netdev_priv(dev); > if (priv->real_dev) { This rcu lock shouldn't be needed as it is acquired already in __dev_queue_xmit(). > + rcu_read_lock(); > rmnet_egress_handler(skb); > + rcu_read_unlock(); > } else { > this_cpu_inc(priv->pcpu_stats->stats.tx_drops); > kfree_skb(skb);