HS 2.0: Add NULL check before dereferencing in hs20-osu-client

xml_node_get_text() may return NULL, so need to check the return value
before using it.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

hs20/client/oma_dm_client.c

@@ -772,6 +772,11 @@ static int oma_dm_replace(struct hs20_osu_client *ctx, xml_node_t *replace,
 	if (node) {
 		char *type;
 		type = xml_node_get_text(ctx->xml, node);
+		if (type == NULL) {
+			wpa_printf(MSG_INFO, "Could not find type text");
+			os_free(locuri);
+			return DM_RESP_BAD_REQUEST;
+		}
 		use_tnds = node &&
 			os_strstr(type, "application/vnd.syncml.dmtnds+xml");
 	}