test binary geo range base size

src/http/modules/ngx_http_geo_module.c

diff --git a/src/http/modules/ngx_http_geo_module.c b/src/http/modules/ngx_http_geo_module.c
index 0b51135..1f3f755 100644
--- a/src/http/modules/ngx_http_geo_module.c
+++ b/src/http/modules/ngx_http_geo_module.c
@@ -1232,7 +1232,7 @@
 
     header = (ngx_http_geo_header_t *) base;
 
-    if (ngx_memcmp(&ngx_http_geo_header, header, 12) != 0) {
+    if (size < 16 || ngx_memcmp(&ngx_http_geo_header, header, 12) != 0) {
         ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
              "incompatible binary geo range base \"%s\"", name->data);
         goto failed;