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(). Fixes: 5602c48cf875 ("vxlan: change vxlan to use UDP socket GRO") Signed-off-by: Kuniyuki Iwashima --- This is 10 years old bug... --- drivers/net/vxlan/vxlan_core.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c index 0ea88232b985..abf3ae04d75b 100644 --- a/drivers/net/vxlan/vxlan_core.c +++ b/drivers/net/vxlan/vxlan_core.c @@ -657,14 +657,18 @@ static struct vxlanhdr *vxlan_gro_prepare_receive(struct sock *sk, struct sk_buff *skb, struct gro_remcsum *grc) { - struct sk_buff *p; struct vxlanhdr *vh, *vh2; unsigned int hlen, off_vx; - struct vxlan_sock *vs = rcu_dereference_sk_user_data(sk); + struct vxlan_sock *vs; + struct sk_buff *p; __be32 flags; skb_gro_remcsum_init(grc); + vs = rcu_dereference_sk_user_data(sk); + if (!vs) + return NULL; + off_vx = skb_gro_offset(skb); hlen = off_vx + sizeof(*vh); vh = skb_gro_header(skb, hlen, off_vx); -- 2.54.0.545.g6539524ca2-goog