[libxml2] Avoid processing entities after encoding conversion failures

[Daniel Veillard <veillard src gnome org>]

commit afd27c21f6b36e22682b7da20d726bce2dcb2f43
Author: Daniel Veillard <veillard redhat com>
Date:   Mon Nov 9 18:07:18 2015 +0800

    Avoid processing entities after encoding conversion failures
    
    For https://bugzilla.gnome.org/show_bug.cgi?id=756527
    and was also raised by Chromium team in the past
    
    When we hit a convwersion failure when switching encoding
    it is bestter to stop parsing there, this was treated as a
    fatal error but the parser was continuing to process to extract
    more errors, unfortunately that makes little sense as the data
    is obviously corrupt and can potentially lead to unexpected behaviour.

 parser.c          |    7 +++++--
 parserInternals.c |   11 ++++++++++-
 2 files changed, 15 insertions(+), 3 deletions(-)
---
diff --git a/parser.c b/parser.c
index 134afe7..c79b4e8 100644
--- a/parser.c
+++ b/parser.c
@@ -10665,7 +10665,8 @@ xmlParseXMLDecl(xmlParserCtxtPtr ctxt) {
        xmlFatalErrMsg(ctxt, XML_ERR_SPACE_REQUIRED, "Blank needed here\n");
     }
     xmlParseEncodingDecl(ctxt);
-    if (ctxt->errNo == XML_ERR_UNSUPPORTED_ENCODING) {
+    if ((ctxt->errNo == XML_ERR_UNSUPPORTED_ENCODING) ||
+         (ctxt->instate == XML_PARSER_EOF)) {
        /*
         * The XML REC instructs us to stop parsing right here
         */
@@ -10789,6 +10790,7 @@ xmlParseDocument(xmlParserCtxtPtr ctxt) {
 
     if (CUR == 0) {
        xmlFatalErr(ctxt, XML_ERR_DOCUMENT_EMPTY, NULL);
+       return(-1);
     }
 
     /*
@@ -10806,7 +10808,8 @@ xmlParseDocument(xmlParserCtxtPtr ctxt) {
         * Note that we will switch encoding on the fly.
         */
        xmlParseXMLDecl(ctxt);
-       if (ctxt->errNo == XML_ERR_UNSUPPORTED_ENCODING) {
+       if ((ctxt->errNo == XML_ERR_UNSUPPORTED_ENCODING) ||
+           (ctxt->instate == XML_PARSER_EOF)) {
            /*
             * The XML REC instructs us to stop parsing right here
             */
diff --git a/parserInternals.c b/parserInternals.c
index df204fd..c8230c1 100644
--- a/parserInternals.c
+++ b/parserInternals.c
@@ -937,6 +937,7 @@ xmlSwitchEncoding(xmlParserCtxtPtr ctxt, xmlCharEncoding enc)
 {
     xmlCharEncodingHandlerPtr handler;
     int len = -1;
+    int ret;
 
     if (ctxt == NULL) return(-1);
     switch (enc) {
@@ -1097,7 +1098,15 @@ xmlSwitchEncoding(xmlParserCtxtPtr ctxt, xmlCharEncoding enc)
     if (handler == NULL)
        return(-1);
     ctxt->charset = XML_CHAR_ENCODING_UTF8;
-    return(xmlSwitchToEncodingInt(ctxt, handler, len));
+    ret = xmlSwitchToEncodingInt(ctxt, handler, len);
+    if ((ret < 0) || (ctxt->errNo == XML_I18N_CONV_FAILED)) {
+        /*
+        * on encoding conversion errors, stop the parser
+        */
+        xmlStopParser(ctxt);
+       ctxt->errNo = XML_I18N_CONV_FAILED;
+    }
+    return(ret);
 }
 
 /**