zone-events: Fixed leaks and possible NULL access in DDNS.

src/knot/nameserver/update.c

@@ -118,6 +118,11 @@ static bool apex_rr_changed(const zone_contents_t *old_contents,
 {
 	knot_rrset_t old_rr = node_rrset(old_contents->apex, type);
 	knot_rrset_t new_rr = node_rrset(new_contents->apex, type);
+	if (knot_rrset_empty(&old_rr)) {
+		return !knot_rrset_empty(&new_rr);
+	} else if (knot_rrset_empty(&new_rr)) {
+		return !knot_rrset_empty(&old_rr);
+	}
 
 	return !knot_rrset_equal(&old_rr, &new_rr, KNOT_RRSET_COMPARE_WHOLE);
 }

src/knot/updates/changesets.c

@@ -220,8 +220,7 @@ int knot_changeset_apply(knot_changeset_t *changeset,
 
 int knot_changeset_merge(knot_changeset_t *ch1, knot_changeset_t *ch2)
 {
-	if (ch1 == NULL || ch2 == NULL || ch1->data != NULL ||
-	    ch2->data != NULL) {
+	if (ch1 == NULL || ch2 == NULL || ch1->data != NULL || ch2->data != NULL) {
 		return KNOT_EINVAL;
 	}
 
@@ -232,6 +231,7 @@ int knot_changeset_merge(knot_changeset_t *ch1, knot_changeset_t *ch2)
 	// Use soa_to and serial from the second changeset
 	// soa_to from the first changeset is redundant, delete it
 	knot_rrset_free(&ch1->soa_to, NULL);
+	knot_rrset_free(&ch2->soa_from, NULL);
 	ch1->soa_to = ch2->soa_to;
 	ch1->serial_to = ch2->serial_to;