From e9a421661a82f5c87add15b39ebd733250c26b45 Mon Sep 17 00:00:00 2001 From: Taehee Yoo Date: Wed, 26 Feb 2020 17:47:06 +0000 Subject: [PATCH] net: rmnet: fix suspicious RCU usage 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 7a7d0f521352da..93642cdd33059b 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 cd0a6bcbe74ade..0d568dcfd65a1c 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 1b74bc16040274..074a8b326c3041 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 509dfc895a33ee..a26e76e9d382be 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) { + rcu_read_lock(); rmnet_egress_handler(skb); + rcu_read_unlock(); } else { this_cpu_inc(priv->pcpu_stats->stats.tx_drops); kfree_skb(skb);