diff --git a/net/ipv6/seg6.c b/net/ipv6/seg6.c
index fa6b64c95d3ae..0c7c6fc16c3c3 100644
--- a/net/ipv6/seg6.c
+++ b/net/ipv6/seg6.c
@@ -191,6 +191,11 @@ static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info)
 		goto out_unlock;
 	}
 
+	if (slen > nla_len(info->attrs[SEG6_ATTR_SECRET])) {
+		err = -EINVAL;
+		goto out_unlock;
+	}
+
 	if (hinfo) {
 		err = seg6_hmac_info_del(net, hmackeyid);
 		if (err)