Improve recursion detection for transclusion and filters (#6970)

core/modules/filters.js

@@ -12,6 +12,9 @@ Adds tiddler filtering methods to the $tw.Wiki object.
 /*global $tw: false */
 "use strict";
 
+/* Maximum permitted filter recursion depth */
+var MAX_FILTER_DEPTH = 300;
+
 /*
 Parses an operation (i.e. a run) within a filter string
 	operators: Array of array of operator nodes into which results should be inserted
@@ -328,7 +331,7 @@ exports.compileFilter = function(filterString) {
 		})());
 	});
 	// Return a function that applies the operations to a source iterator of tiddler titles
-	var compiled = $tw.perf.measure("filter: " + filterString,function filterFunction(source,widget) {
+	var fnMeasured = $tw.perf.measure("filter: " + filterString,function filterFunction(source,widget) {
 		if(!source) {
 			source = self.each;
 		} else if(typeof source === "object") { // Array or hashmap
@@ -338,9 +341,15 @@ exports.compileFilter = function(filterString) {
 			widget = $tw.rootWidget;
 		}
 		var results = new $tw.utils.LinkedList();
-		$tw.utils.each(operationFunctions,function(operationFunction) {
-			operationFunction(results,source,widget);
-		});
+		self.filterRecursionCount = (self.filterRecursionCount || 0) + 1;
+		if(self.filterRecursionCount < MAX_FILTER_DEPTH) {
+			$tw.utils.each(operationFunctions,function(operationFunction) {
+				operationFunction(results,source,widget);
+			});
+		} else {
+			results.push("/**-- Excessive filter recursion --**/");
+		}
+		self.filterRecursionCount = self.filterRecursionCount - 1;
 		return results.toArray();
 	});
 	if(this.filterCacheCount >= 2000) {
@@ -350,9 +359,9 @@ exports.compileFilter = function(filterString) {
 		this.filterCache = Object.create(null);
 		this.filterCacheCount = 0;
 	}
-	this.filterCache[filterString] = compiled;
+	this.filterCache[filterString] = fnMeasured;
 	this.filterCacheCount++;
-	return compiled;
+	return fnMeasured;
 };
 
 })();

core/modules/widgets/error.js

@@ -0,0 +1,63 @@
+/*\
+title: $:/core/modules/widgets/error.js
+type: application/javascript
+module-type: widget
+
+Error widget
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+var Widget = require("$:/core/modules/widgets/widget.js").widget;
+
+var ErrorWidget = function(parseTreeNode,options) {
+	this.initialise(parseTreeNode,options);
+};
+
+/*
+Inherit from the base widget class
+*/
+ErrorWidget.prototype = new Widget();
+
+/*
+Render this widget into the DOM
+*/
+ErrorWidget.prototype.render = function(parent,nextSibling) {
+	this.parentDomNode = parent;
+	this.computeAttributes();
+	this.execute();
+	var message = this.getAttribute("$message","Unknown error"),
+		domNode = this.document.createElement("span");
+	domNode.appendChild(this.document.createTextNode(message));
+	domNode.className = "tc-error";
+	parent.insertBefore(domNode,nextSibling);
+	this.domNodes.push(domNode);
+};
+
+/*
+Compute the internal state of the widget
+*/
+ErrorWidget.prototype.execute = function() {
+	// Nothing to do for a text node
+};
+
+/*
+Selectively refreshes the widget if needed. Returns true if the widget or any of its children needed re-rendering
+*/
+ErrorWidget.prototype.refresh = function(changedTiddlers) {
+	var changedAttributes = this.computeAttributes();
+	if(changedAttributes["$message"]) {
+		this.refreshSelf();
+		return true;
+	} else {
+		return false;
+	}
+};
+
+exports.error = ErrorWidget;
+
+})();

core/modules/widgets/widget.js

@@ -12,6 +12,9 @@ Widget base class
 /*global $tw: false */
 "use strict";
 
+/* Maximum permitted depth of the widget tree for recursion detection */
+var MAX_WIDGET_TREE_DEPTH = 1000;
+
 /*
 Create a widget object for a parse tree node
 	parseTreeNode: reference to the parse tree node to be rendered
@@ -358,6 +361,20 @@ Widget.prototype.assignAttributes = function(domNode,options) {
 	}
 };
 
+/*
+Get the number of ancestor widgets for this widget
+*/
+Widget.prototype.getAncestorCount = function() {
+	if(this.ancestorCount === undefined) {
+		if(this.parentWidget) {
+			this.ancestorCount = this.parentWidget.getAncestorCount() + 1;
+		} else {
+			this.ancestorCount = 0;
+		}
+	}
+	return this.ancestorCount;
+};
+
 /*
 Make child widgets correspondng to specified parseTreeNodes
 */
@@ -365,21 +382,29 @@ Widget.prototype.makeChildWidgets = function(parseTreeNodes,options) {
 	options = options || {};
 	this.children = [];
 	var self = this;
-	// Create set variable widgets for each variable
-	$tw.utils.each(options.variables,function(value,name) {
-		var setVariableWidget = {
-			type: "set",
-			attributes: {
-				name: {type: "string", value: name},
-				value: {type: "string", value: value}
-			},
-			children: parseTreeNodes
-		};
-		parseTreeNodes = [setVariableWidget];
-	});
-	$tw.utils.each(parseTreeNodes || (this.parseTreeNode && this.parseTreeNode.children),function(childNode) {
-		self.children.push(self.makeChildWidget(childNode));
-	});
+	// Check for too much recursion
+	if(this.getAncestorCount() > MAX_WIDGET_TREE_DEPTH) {
+		this.children.push(this.makeChildWidget({type: "error", attributes: {
+			"$message": {type: "string", value: $tw.language.getString("Error/RecursiveTransclusion")}
+		}}));
+	} else {
+		// Create set variable widgets for each variable
+		$tw.utils.each(options.variables,function(value,name) {
+			var setVariableWidget = {
+				type: "set",
+				attributes: {
+					name: {type: "string", value: name},
+					value: {type: "string", value: value}
+				},
+				children: parseTreeNodes
+			};
+			parseTreeNodes = [setVariableWidget];
+		});
+		// Create the child widgets
+		$tw.utils.each(parseTreeNodes || (this.parseTreeNode && this.parseTreeNode.children),function(childNode) {
+			self.children.push(self.makeChildWidget(childNode));
+		});
+	}
 };
 
 /*

editions/test/tiddlers/tests/data/filters/Recursion.tid

@@ -0,0 +1,15 @@
+title: Filters/Recursion
+description: Filter recursion detection
+type: text/vnd.tiddlywiki-multiple
+tags: [[$:/tags/wiki-test-spec]]
+
+title: Output
+
+\whitespace trim
+\define myfilter() [subfilter<myfilter>]
+
+<$text text={{{ [subfilter<myfilter>] }}}/>
++
+title: ExpectedResult
+
+<p>/**-- Excessive filter recursion --**/</p>

editions/test/tiddlers/tests/data/transclude/Recursion.tid

@@ -0,0 +1,13 @@
+title: Transclude/Recursion
+description: Transclusion recursion detection
+type: text/vnd.tiddlywiki-multiple
+tags: [[$:/tags/wiki-test-spec]]
+
+title: Output
+
+\whitespace trim
+<$transclude $tiddler="Output"/>
++
+title: ExpectedResult
+
+<p><span class="tc-error">Recursive transclusion error in transclude widget</span></p>

editions/tw5.com/tiddlers/widgets/ErrorWidget.tid

@@ -0,0 +1,17 @@
+caption: error
+created: 20220909111836951
+modified: 20220909111836951
+tags: Widgets
+title: ErrorWidget
+type: text/vnd.tiddlywiki
+
+<<.from-version "5.3.0">> The <<.wlink ErrorWidget>> widget is used by the core to display error messages such as the recursion errors reported by the <<.wlink TranscludeWidget>> widget.
+
+The <<.wlink ErrorWidget>> does not provide any useful functionality to end users. It is only required by the core for technical reasons.
+
+! Content and Attributes
+
+The content of the <<.wlink ErrorWidget>> widget is ignored.
+
+|!Attribute |!Description |
+|$message |The error message |