From 235b15a590eecf97b09e87bdb7e4f8333e9de129 Mon Sep 17 00:00:00 2001
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Mon May 8 17:58:02 2023 +0200
Subject: [PATCH 2/2] SAX: Always initialize SAX1 element handlers

Follow-up to commit d0c3f01e. A parser context will be initialized to
SAX version 2, but this can be overridden with XML_PARSE_SAX1 later,
so we must initialize the SAX1 element handlers as well.

Change the check in xmlDetectSAX2 to only look for XML_SAX2_MAGIC, so
we don't switch to SAX1 if the SAX2 element handlers are NULL.

CVE: CVE-2023-39615

Upstream-Status: Backport [https://gitlab.gnome.org/GNOME/libxml2/-/commit/235b15a590eecf97b09e87bdb7e4f8333e9de129]

Signed-off-by: Soumya Sambu <soumya.sambu@windriver.com>
---
 SAX2.c   | 11 +++++++----
 parser.c |  5 +----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/SAX2.c b/SAX2.c
index 0319246..f7c77c2 100644
--- a/SAX2.c
+++ b/SAX2.c
@@ -2842,20 +2842,23 @@ xmlSAXVersion(xmlSAXHandler *hdlr, int version)
 {
     if (hdlr == NULL) return(-1);
     if (version == 2) {
-	hdlr->startElement = NULL;
-	hdlr->endElement = NULL;
	hdlr->startElementNs = xmlSAX2StartElementNs;
	hdlr->endElementNs = xmlSAX2EndElementNs;
	hdlr->serror = NULL;
	hdlr->initialized = XML_SAX2_MAGIC;
 #ifdef LIBXML_SAX1_ENABLED
     } else if (version == 1) {
-	hdlr->startElement = xmlSAX2StartElement;
-	hdlr->endElement = xmlSAX2EndElement;
	hdlr->initialized = 1;
 #endif /* LIBXML_SAX1_ENABLED */
     } else
         return(-1);
+#ifdef LIBXML_SAX1_ENABLED
+    hdlr->startElement = xmlSAX2StartElement;
+    hdlr->endElement = xmlSAX2EndElement;
+#else
+    hdlr->startElement = NULL;
+    hdlr->endElement = NULL;
+#endif /* LIBXML_SAX1_ENABLED */
     hdlr->internalSubset = xmlSAX2InternalSubset;
     hdlr->externalSubset = xmlSAX2ExternalSubset;
     hdlr->isStandalone = xmlSAX2IsStandalone;
diff --git a/parser.c b/parser.c
index b781c80..738dbee 100644
--- a/parser.c
+++ b/parser.c
@@ -1109,10 +1109,7 @@ xmlDetectSAX2(xmlParserCtxtPtr ctxt) {
     if (ctxt == NULL) return;
     sax = ctxt->sax;
 #ifdef LIBXML_SAX1_ENABLED
-    if ((sax) &&  (sax->initialized == XML_SAX2_MAGIC) &&
-        ((sax->startElementNs != NULL) ||
-         (sax->endElementNs != NULL) ||
-         ((sax->startElement == NULL) && (sax->endElement == NULL))))
+    if ((sax) && (sax->initialized == XML_SAX2_MAGIC))
         ctxt->sax2 = 1;
 #else
     ctxt->sax2 = 1;
--
2.40.0
