checks: Fix crash in graph_child_address if 'reg' cell size != 1

If an endpoint node has a 'reg' property which consists of more than
one cell (4 bytes) and given that matching '#address-cells' and '#size-cells'
properties are specified on the port node an assertion is triggered in
check_graph_child_address() before the relevant diagnostic checks in
check_graph_reg() (called by check_graph_port() and check_graph_endpoint()) are executed.

The issue is fixed by making graph_child_address depend on the
graph_port and graph_endpoint checks.

Additionally the assertion can also be triggered if the length of the
'reg' property is less than 4 bytes e.g. by specifying
'reg = "a";'. In that case however other warnings are produced
highlighting the malformed property before dtc crashes.

Example dts file triggering the issue:

/dts-v1/;
 / {
	bar: bar {
		port {
			bar_con: endpoint {
				remote-endpoint = <&foo_con>;
			};
		};
	};
	foo {
		port {
			#address-cells = <1>;
			#size-cells = <1>; // should always be 0
			foo_con: endpoint@1 {
				reg = <1 2>; // causes assertion failure instead of diagnostic
				remote-endpoint = <&bar_con>;
			};
		};
	};
};

Signed-off-by: Johannes Beisswenger <johannes.beisswenger@cetitec.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

checks.c

@@ -1785,31 +1785,6 @@ static void check_graph_nodes(struct check *c, struct dt_info *dti,
 }
 WARNING(graph_nodes, check_graph_nodes, NULL);
 
-static void check_graph_child_address(struct check *c, struct dt_info *dti,
-				      struct node *node)
-{
-	int cnt = 0;
-	struct node *child;
-
-	if (node->bus != &graph_ports_bus && node->bus != &graph_port_bus)
-		return;
-
-	for_each_child(node, child) {
-		struct property *prop = get_property(child, "reg");
-
-		/* No error if we have any non-zero unit address */
-		if (prop && propval_cell(prop) != 0)
-			return;
-
-		cnt++;
-	}
-
-	if (cnt == 1 && node->addr_cells != -1)
-		FAIL(c, dti, node, "graph node has single child node '%s', #address-cells/#size-cells are not necessary",
-		     node->children->name);
-}
-WARNING(graph_child_address, check_graph_child_address, NULL, &graph_nodes);
-
 static void check_graph_reg(struct check *c, struct dt_info *dti,
 			    struct node *node)
 {
@@ -1900,6 +1875,31 @@ static void check_graph_endpoint(struct check *c, struct dt_info *dti,
 }
 WARNING(graph_endpoint, check_graph_endpoint, NULL, &graph_nodes);
 
+static void check_graph_child_address(struct check *c, struct dt_info *dti,
+				      struct node *node)
+{
+	int cnt = 0;
+	struct node *child;
+
+	if (node->bus != &graph_ports_bus && node->bus != &graph_port_bus)
+		return;
+
+	for_each_child(node, child) {
+		struct property *prop = get_property(child, "reg");
+
+		/* No error if we have any non-zero unit address */
+                if (prop && propval_cell(prop) != 0 )
+			return;
+
+		cnt++;
+	}
+
+	if (cnt == 1 && node->addr_cells != -1)
+		FAIL(c, dti, node, "graph node has single child node '%s', #address-cells/#size-cells are not necessary",
+		     node->children->name);
+}
+WARNING(graph_child_address, check_graph_child_address, NULL, &graph_nodes, &graph_port, &graph_endpoint);
+
 static struct check *check_table[] = {
 	&duplicate_node_names, &duplicate_property_names,
 	&node_name_chars, &node_name_format, &property_name_chars,