From 311633b604063a8a5d3fbc74d0565b42df721f68 Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Tue, 9 Jul 2019 23:24:54 -0700 Subject: hsr: switch ->dellink() to ->ndo_uninit() Switching from ->priv_destructor to dellink() has an unexpected consequence: existing RCU readers, that is, hsr_port_get_hsr() callers, may still be able to read the port list. Instead of checking the return value of each hsr_port_get_hsr(), we can just move it to ->ndo_uninit() which is called after device unregister and synchronize_net(), and we still have RTNL lock there. Fixes: b9a1e627405d ("hsr: implement dellink to clean up resources") Fixes: edf070a0fb45 ("hsr: fix a NULL pointer deref in hsr_dev_xmit()") Reported-by: syzbot+097ef84cdc95843fbaa8@syzkaller.appspotmail.com Cc: Arvid Brodin Signed-off-by: Cong Wang Signed-off-by: David S. Miller --- net/hsr/hsr_device.c | 18 ++++++++---------- net/hsr/hsr_device.h | 1 - net/hsr/hsr_netlink.c | 7 ------- 3 files changed, 8 insertions(+), 18 deletions(-) (limited to 'net') diff --git a/net/hsr/hsr_device.c b/net/hsr/hsr_device.c index f0f9b493c47b..f509b495451a 100644 --- a/net/hsr/hsr_device.c +++ b/net/hsr/hsr_device.c @@ -227,13 +227,8 @@ static int hsr_dev_xmit(struct sk_buff *skb, struct net_device *dev) struct hsr_port *master; master = hsr_port_get_hsr(hsr, HSR_PT_MASTER); - if (master) { - skb->dev = master->dev; - hsr_forward_skb(skb, master); - } else { - atomic_long_inc(&dev->tx_dropped); - dev_kfree_skb_any(skb); - } + skb->dev = master->dev; + hsr_forward_skb(skb, master); return NETDEV_TX_OK; } @@ -348,7 +343,11 @@ static void hsr_announce(struct timer_list *t) rcu_read_unlock(); } -void hsr_dev_destroy(struct net_device *hsr_dev) +/* This has to be called after all the readers are gone. + * Otherwise we would have to check the return value of + * hsr_port_get_hsr(). + */ +static void hsr_dev_destroy(struct net_device *hsr_dev) { struct hsr_priv *hsr; struct hsr_port *port; @@ -364,8 +363,6 @@ void hsr_dev_destroy(struct net_device *hsr_dev) del_timer_sync(&hsr->prune_timer); del_timer_sync(&hsr->announce_timer); - synchronize_rcu(); - hsr_del_self_node(&hsr->self_node_db); hsr_del_nodes(&hsr->node_db); } @@ -376,6 +373,7 @@ static const struct net_device_ops hsr_device_ops = { .ndo_stop = hsr_dev_close, .ndo_start_xmit = hsr_dev_xmit, .ndo_fix_features = hsr_fix_features, + .ndo_uninit = hsr_dev_destroy, }; static struct device_type hsr_type = { diff --git a/net/hsr/hsr_device.h b/net/hsr/hsr_device.h index d0fa6b0696d2..6d7759c4f5f9 100644 --- a/net/hsr/hsr_device.h +++ b/net/hsr/hsr_device.h @@ -14,7 +14,6 @@ void hsr_dev_setup(struct net_device *dev); int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2], unsigned char multicast_spec, u8 protocol_version); -void hsr_dev_destroy(struct net_device *hsr_dev); void hsr_check_carrier_and_operstate(struct hsr_priv *hsr); bool is_hsr_master(struct net_device *dev); int hsr_get_max_mtu(struct hsr_priv *hsr); diff --git a/net/hsr/hsr_netlink.c b/net/hsr/hsr_netlink.c index 160edd24de4e..8f8337f893ba 100644 --- a/net/hsr/hsr_netlink.c +++ b/net/hsr/hsr_netlink.c @@ -69,12 +69,6 @@ static int hsr_newlink(struct net *src_net, struct net_device *dev, return hsr_dev_finalize(dev, link, multicast_spec, hsr_version); } -static void hsr_dellink(struct net_device *hsr_dev, struct list_head *head) -{ - hsr_dev_destroy(hsr_dev); - unregister_netdevice_queue(hsr_dev, head); -} - static int hsr_fill_info(struct sk_buff *skb, const struct net_device *dev) { struct hsr_priv *hsr; @@ -119,7 +113,6 @@ static struct rtnl_link_ops hsr_link_ops __read_mostly = { .priv_size = sizeof(struct hsr_priv), .setup = hsr_dev_setup, .newlink = hsr_newlink, - .dellink = hsr_dellink, .fill_info = hsr_fill_info, }; -- cgit v1.2.3-59-g8ed1b