diff --git a/net/ceph/mon_client.c b/net/ceph/mon_client.c
index c56457378d00..bcbcf47506c9 100644
--- a/net/ceph/mon_client.c
+++ b/net/ceph/mon_client.c
@@ -1141,6 +1141,9 @@ static int build_initial_monmap(struct ceph_mon_client *monc)
 	int num_mon = opt->num_mon;
 	int i;
 
+	if (num_mon < 1 || num_mon > CEPH_MAX_MON)
+		return -EINVAL;
+
 	/* build initial monmap */
 	monc->monmap = kzalloc_flex(*monc->monmap, mon_inst, num_mon);
 	if (!monc->monmap)