fix(platform-browser): prevent clobbered elements from freezing the browser

see
4f69d38f09

packages/platform-browser/src/browser/browser_adapter.ts

@@ -61,6 +61,14 @@ const _chromeNumKeyPadMap = {
   '\x90': 'NumLock'
 };
 
+let nodeContains: (a: any, b: any) => boolean;
+
+if (global['Node']) {
+  nodeContains = global['Node'].prototype.contains || function(node) {
+    return !!(this.compareDocumentPosition(node) & 16);
+  };
+}
+
 /**
  * A `DomAdapter` powered by full browser DOM APIs.
  *
@@ -107,6 +115,7 @@ export class BrowserDomAdapter extends GenericBrowserDomAdapter {
 
   get attrToPropMap(): any { return _attrToPropMap; }
 
+  contains(nodeA: any, nodeB: any): boolean { return nodeContains.call(nodeA, nodeB); }
   querySelector(el: Element, selector: string): any { return el.querySelector(selector); }
   querySelectorAll(el: any, selector: string): any[] { return el.querySelectorAll(selector); }
   on(el: Node, evt: any, listener: any) { el.addEventListener(evt, listener, false); }

packages/platform-browser/src/dom/dom_adapter.ts

@@ -52,6 +52,7 @@ export abstract class DomAdapter {
   /** @internal */
   _attrToPropMap: {[key: string]: string};
 
+  abstract contains(nodeA: any, nodeB: any): boolean;
   abstract parse(templateHtml: string): any;
   abstract querySelector(el: any, selector: string): any;
   abstract querySelectorAll(el: any, selector: string): any[];

packages/platform-browser/src/security/html_sanitizer.ts

@@ -9,7 +9,6 @@
 import {isDevMode} from '@angular/core';
 
 import {DomAdapter, getDOM} from '../dom/dom_adapter';
-import {DOCUMENT} from '../dom/dom_tokens';
 
 import {sanitizeSrcset, sanitizeUrl} from './url_sanitizer';
 
@@ -146,11 +145,15 @@ class SanitizingHtmlSerializer {
         if (DOM.isElementNode(current)) {
           this.endElement(current as Element);
         }
-        if (DOM.nextSibling(current)) {
-          current = DOM.nextSibling(current);
+
+        let next = checkClobberedElement(current, DOM.nextSibling(current));
+
+        if (next) {
+          current = next;
           break;
         }
-        current = DOM.parentElement(current);
+
+        current = checkClobberedElement(current, DOM.parentElement(current));
       }
     }
     return this.buf.join('');
@@ -191,7 +194,15 @@ class SanitizingHtmlSerializer {
     }
   }
 
-  private chars(chars: any /** TODO #9100 */) { this.buf.push(encodeEntities(chars)); }
+  private chars(chars: string) { this.buf.push(encodeEntities(chars)); }
+}
+
+function checkClobberedElement(node: Node, nextNode: Node): Node {
+  if (nextNode && DOM.contains(node, nextNode)) {
+    throw new Error(
+        `Failed to sanitize html because the element is clobbered: ${DOM.getOuterHTML(node)}`);
+  }
+  return nextNode;
 }
 
 // Regular Expressions for parsing tags and attributes

packages/platform-browser/test/security/html_sanitizer_spec.ts

@@ -112,6 +112,28 @@ export function main() {
       }
     });
 
+    it('should not enter an infinite loop on clobbered elements', () => {
+      // Some browsers are vulnerable to clobbered elements and will throw an expected exception
+      // IE and EDGE does not seems to be affected by those cases
+      // Anyway what we want to test is that browsers do not enter an infinite loop which would
+      // result in a timeout error for the test.
+      try {
+        sanitizeHtml(defaultDoc, '<form><input name="parentNode" /></form>');
+      } catch (e) {
+        // depending on the browser, we might ge an exception
+      }
+      try {
+        sanitizeHtml(defaultDoc, '<form><input name="nextSibling" /></form>')
+      } catch (e) {
+        // depending on the browser, we might ge an exception
+      }
+      try {
+        sanitizeHtml(defaultDoc, '<form><div><div><input name="nextSibling" /></div></div></form>');
+      } catch (e) {
+        // depending on the browser, we might ge an exception
+      }
+    });
+
     if (browserDetection.isWebkit) {
       it('should prevent mXSS attacks', function() {
         expect(sanitizeHtml(defaultDoc, '<a href="&#x3000;javascript:alert(1)">CLICKME</a>'))

packages/platform-server/src/parse5_adapter.ts

@@ -63,6 +63,15 @@ export class Parse5DomAdapter extends DomAdapter {
     setRootDomAdapter(new Parse5DomAdapter());
   }
 
+  contains(nodeA: any, nodeB: any): boolean {
+    let inner = nodeB;
+    while (inner) {
+      if (inner === nodeA) return true;
+      inner = inner.parent;
+    }
+    return false;
+  }
+
   hasProperty(element: any, name: string): boolean {
     return _HTMLElementPropertyList.indexOf(name) > -1;
   }

packages/platform-webworker/src/web_workers/worker/worker_adapter.ts

@@ -44,6 +44,7 @@ export class WorkerDomAdapter extends DomAdapter {
     }
   }
 
+  contains(nodeA: any, nodeB: any): boolean { throw 'not implemented'; }
   hasProperty(element: any, name: string): boolean { throw 'not implemented'; }
   setProperty(el: Element, name: string, value: any) { throw 'not implemented'; }
   getProperty(el: Element, name: string): any { throw 'not implemented'; }