From c7466336934d7d22378a10c7c9bb5d77a8f7d11b Mon Sep 17 00:00:00 2001
From: Raymond Hill <rhill@raymondhill.net>
Date: Sun, 6 Oct 2024 14:27:55 -0400
Subject: [PATCH] Validate result type of XPath expressions

Related issue:
https://github.com/uBlockOrigin/uBlock-issues/issues/3403

To ensure XPath expressions not meant to return a nodeset are
discarded at compile time.
---
 src/js/static-filtering-parser.js | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/js/static-filtering-parser.js b/src/js/static-filtering-parser.js
index 1249b07b8..8f95b88d6 100644
--- a/src/js/static-filtering-parser.js
+++ b/src/js/static-filtering-parser.js
@@ -4116,9 +4116,11 @@ class ExtSelectorCompiler {
     compileXpathExpression(s) {
         const r = this.unquoteString(s);
         if ( r.i !== s.length ) { return; }
-        if ( globalThis.document instanceof Object === false ) { return r.s; }
+        const doc = globalThis.document;
+        if ( doc instanceof Object === false ) { return r.s; }
         try {
-            globalThis.document.createExpression(r.s, null);
+            const expr = doc.createExpression(r.s, null);
+            expr.evaluate(doc, XPathResult.ANY_UNORDERED_NODE_TYPE);
         } catch (e) {
             return;
         }