From 31ad3e7ab049cf6a663566f2f809d8d1a90c996b Mon Sep 17 00:00:00 2001
From: Josh Goebel <me@joshgoebel.com>
Date: Sat, 2 May 2020 14:25:26 -0400
Subject: [PATCH 1/3] fix[parser] add edge case handle for illegal 0 width
 matches

---
 src/highlight.js | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/highlight.js b/src/highlight.js
index d60330fba5..d1eb36e79e 100644
--- a/src/highlight.js
+++ b/src/highlight.js
@@ -365,6 +365,14 @@ const HLJS = function(hljs) {
         }
       }
 
+      // edge case for when illegal matches $ (end of line) which is technically
+      // a 0 width match but not a begin/end match so it's not caught by the
+      // first handler (when ignoreIllegals is true)
+      if (match.type === "illegal" && lexeme === "") {
+        // advance so we aren't stuck in an infinite loop
+        return 1;
+      }
+
       /*
       Why might be find ourselves here?  Only one occasion now.  An end match that was
       triggered but could not be completed.  When might this happen?  When an `endSameasBegin`

From a9a5adf9ae5844378a612b3fa02c64e13ee24ea8 Mon Sep 17 00:00:00 2001
From: Josh Goebel <me@joshgoebel.com>
Date: Sat, 2 May 2020 14:50:26 -0400
Subject: [PATCH 2/3] last ditch catch all

---
 src/highlight.js | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/highlight.js b/src/highlight.js
index d1eb36e79e..07f61b6aec 100644
--- a/src/highlight.js
+++ b/src/highlight.js
@@ -373,6 +373,15 @@ const HLJS = function(hljs) {
         return 1;
       }
 
+      // infinite loops are BAD, this is a last ditch catch all. if we have a
+      // decent number of iterations yet our index (cursor position in our
+      // parsing) still 3x behind our index then something is very wrong
+      // so we bail
+      if (iterations > 100000 && iterations > match.index * 3) {
+        const err = new Error('potential infinite loop, way more iterations than matches');
+        throw err;
+      }
+
       /*
       Why might be find ourselves here?  Only one occasion now.  An end match that was
       triggered but could not be completed.  When might this happen?  When an `endSameasBegin`
@@ -404,12 +413,14 @@ const HLJS = function(hljs) {
     var mode_buffer = '';
     var relevance = 0;
     var index = 0;
+    var iterations = 0;
     var continueScanAtSamePosition = false;
 
     try {
       top.matcher.considerAll();
 
       for (;;) {
+        iterations++;
         if (continueScanAtSamePosition) {
           continueScanAtSamePosition = false;
           // only regexes not matched previously will now be

From 9edb030d6edd5190401594612b9e15f9268b949c Mon Sep 17 00:00:00 2001
From: Josh Goebel <me@joshgoebel.com>
Date: Sun, 3 May 2020 14:00:10 -0400
Subject: [PATCH 3/3] Update CHANGES.md

---
 CHANGES.md | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index 8d9201c218..e5e293e3e2 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -37,10 +37,9 @@ Brower build:
 - [Issue](https://github.com/highlightjs/highlight.js/issues/2505) (bug) Fix: Version 10 fails to load as CommonJS module. (#2511) [Josh Goebel][]
 - [Issue](https://github.com/highlightjs/highlight.js/issues/2505) (removal) AMD module loading support has been removed. (#2511) [Josh Goebel][]
 
-
 Parser Engine Changes:
 
-- ...
+- [Issue](https://github.com/highlightjs/highlight.js/issues/2522) fix(parser) Fix freez issue with illegal 0 width matches (#2524) [Josh Goebel][]
 
 
 [Josh Goebel]: https://github.com/yyyc514