From 63fa7b922a169ed6b86a4c6678140795c28657f5 Mon Sep 17 00:00:00 2001
From: Nick Wellnhofer <[email protected]>
Date: Sun, 20 Nov 2022 19:54:34 +0100
Subject: [PATCH 20/28] html: Fix check for end of comment in push parser

Make sure to reset checkIndex. Handle case where "--" or "--!" is at the
end of the buffer. Fix "avail" check in htmlParseOrTryFinish.

Reference: https://github.com/GNOME/libxml2/commit/c93679381c565f4c110c7a6110372bd6d0610308
Conflict: HTMLparser.c:<htmlParseLookupCommentEnd>,<htmlParseTryOrFinish>
---
 HTMLparser.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/HTMLparser.c b/HTMLparser.c
index e0b32fe..746edf6 100644
--- a/HTMLparser.c
+++ b/HTMLparser.c
@@ -5405,14 +5405,22 @@ static int
 htmlParseLookupCommentEnd(htmlParserCtxtPtr ctxt)
 {
     int mark = 0;
+    int offset;
     int cur = CUR_PTR - BASE_PTR;
 
-    while (mark >= 0) {
+    while (1) {
 	mark = htmlParseLookupSequence(ctxt, '-', '-', 0, 0);
-	if ((mark < 0) ||
-	    (NXT(mark+2) == '>') ||
+	if (mark < 0)
+	    break;
+	if ((NXT(mark+2) == '>') ||
 	    ((NXT(mark+2) == '!') && (NXT(mark+3) == '>'))) {
-	    return mark;
+	    ctxt->checkIndex = 0;
+	    break;
+	}
+	offset = (NXT(mark+2) == '!') ? 3 : 2;
+	if (mark + offset >= ctxt->input->end - ctxt->input->cur) {
+	    ctxt->checkIndex = mark;
+	    return(-1);
 	}
 	ctxt->checkIndex = cur + mark + 1;
     }
@@ -5949,6 +5957,8 @@ htmlParseTryOrFinish(htmlParserCtxtPtr ctxt, int terminate) {
 			break;
 		    }
 		} else {
+		    if ((cur == '<') && (next == '!') && (avail < 4))
+			goto done;
 		    /*
 		     * Sometimes DOCTYPE arrives in the middle of the document
 		     */
@@ -5984,8 +5994,6 @@ htmlParseTryOrFinish(htmlParserCtxtPtr ctxt, int terminate) {
 #endif
 			htmlParsePI(ctxt);
 			ctxt->instate = XML_PARSER_CONTENT;
-		    } else if ((cur == '<') && (next == '!') && (avail < 4)) {
-			goto done;
 		    } else if ((cur == '<') && (next == '/')) {
 			ctxt->instate = XML_PARSER_END_TAG;
 			ctxt->checkIndex = 0;
-- 
2.27.0