Core: protection from cycles with named locations and post_action. Now redirects to named locations are counted against normal uri changes limit, and post_action respects this limit as well. As a result at least the following (bad) configurations no longer trigger infinite cycles: 1. Post action which recursively triggers post action: location / { post_action /index.html; } 2. Post action pointing to nonexistent named location: location / { post_action @nonexistent; } 3. Recursive error page for 500 (Internal Server Error) pointing to a nonexistent named location: location / { recursive_error_pages on; error_page 500 @nonexistent; return 500; }

--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -2524,6 +2524,16 @@ ngx_http_named_location(ngx_http_request
     ngx_http_core_main_conf_t   *cmcf;
 
     r->main->count++;
+    r->uri_changes--;
+
+    if (r->uri_changes == 0) {
+        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                      "rewrite or internal redirection cycle "
+                      "while redirect to named location \"%V\"", name);
+
+        ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
+        return NGX_DONE;
+    }
 
     cscf = ngx_http_get_module_srv_conf(r, ngx_http_core_module);