[PATCH net 1/2] vxlan: lock RCU on TX path

[Jakub Kicinski]

There is no guarantees that callers of the TX path will hold
the RCU lock.  Grab it explicitly.

Fixes: c6fcc4fc5f8b ("vxlan: avoid using stale vxlan socket.")
Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
---
 drivers/net/vxlan.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 4e27c5b09600..e53ee696c962 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2108,6 +2108,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct 
net_device *dev,
        src_port = udp_flow_src_port(dev_net(dev), skb, vxlan->cfg.port_min,
                                     vxlan->cfg.port_max, true);
 
+       rcu_read_lock();
        if (dst->sa.sa_family == AF_INET) {
                struct vxlan_sock *sock4 = rcu_dereference(vxlan->vn4_sock);
                struct rtable *rt;
@@ -2130,7 +2131,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct 
net_device *dev,
                                                    dst_port, vni, &rt->dst,
                                                    rt->rt_flags);
                        if (err)
-                               return;
+                               goto out_unlock;
                } else if (info->key.tun_flags & TUNNEL_DONT_FRAGMENT) {
                        df = htons(IP_DF);
                }
@@ -2169,7 +2170,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct 
net_device *dev,
                                                    dst_port, vni, ndst,
                                                    rt6i_flags);
                        if (err)
-                               return;
+                               goto out_unlock;
                }
 
                tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
@@ -2186,6 +2187,8 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct 
net_device *dev,
                                     label, src_port, dst_port, !udp_sum);
 #endif
        }
+out_unlock:
+       rcu_read_unlock();
        return;
 
 drop:
@@ -2194,6 +2197,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct 
net_device *dev,
        return;
 
 tx_error:
+       rcu_read_unlock();
        if (err == -ELOOP)
                dev->stats.collisions++;
        else if (err == -ENETUNREACH)
-- 
2.11.0