[PATCH 4.10 15/63] vxlan: lock RCU on TX path

[Greg Kroah-Hartman]

4.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jakub Kicinski <jakub.kicin...@netronome.com>


[ Upstream commit 56de859e9967c070464a9a9f4f18d73f9447298e ]

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>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/net/vxlan.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2062,6 +2062,7 @@ static void vxlan_xmit_one(struct sk_buf
        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;
@@ -2084,7 +2085,7 @@ static void vxlan_xmit_one(struct sk_buf
                                                    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);
                }
@@ -2123,7 +2124,7 @@ static void vxlan_xmit_one(struct sk_buf
                                                    dst_port, vni, ndst,
                                                    rt6i_flags);
                        if (err)
-                               return;
+                               goto out_unlock;
                }
 
                tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
@@ -2140,6 +2141,8 @@ static void vxlan_xmit_one(struct sk_buf
                                     label, src_port, dst_port, !udp_sum);
 #endif
        }
+out_unlock:
+       rcu_read_unlock();
        return;
 
 drop:
@@ -2148,6 +2151,7 @@ drop:
        return;
 
 tx_error:
+       rcu_read_unlock();
        if (err == -ELOOP)
                dev->stats.collisions++;
        else if (err == -ENETUNREACH)