diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 8a1c5698983c..3fb914196987 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -572,6 +572,7 @@ static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
 	bool ret = false;
 	u64 ack_seq;
 
+	memset(&opts->ext_copy, 0, sizeof(opts->ext_copy));
 	opts->csum_reqd = READ_ONCE(msk->csum_enabled);
 	mpext = skb ? mptcp_get_ext(skb) : NULL;