In the Linux kernel, the following vulnerability has been resolved:
vxlan: Fix potential null-ptr-deref in vxlan_gro_prepare_receive().
udp_tunnel_sock_release() could set sk->sk_user_data to NULL
while vxlan_gro_prepare_receive() is running.
Let’s check if rcu_dereference_sk_user_data() is NULL after
skb_gro_remcsum_init().
