1 files changed, 6 insertions, 0 deletions

diff --git a/net/dccp/input.c b/net/dccp/input.c
index f01d588299c8..c74034cf7ede 100644
--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -562,6 +562,12 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
                 return 0;
         }
 
+        if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
+                dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
+                               DCCP_PKT_SYNCACK);
+                goto discard;
+        }
+
         switch (sk->sk_state) {
         case DCCP_CLOSED:
                 return 1;