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Fix quadratic runtime when parsing CDATA sections

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Use optimized concatenation for CDATA sections in addition to normal
text. This also affects HTML script content.

Found by OSS-Fuzz.
This commit is contained in:
Nick Wellnhofer 2021-02-03 13:48:40 +01:00
parent f93ca3e140
commit acb3566739
1 changed files with 33 additions and 31 deletions
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64
SAX2.c
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@ -2493,20 +2493,21 @@ xmlSAX2Reference(void *ctx, const xmlChar *name)
}
/**
* xmlSAX2Characters:
* xmlSAX2Text:
* @ctx: the user data (XML parser context)
* @ch: a xmlChar string
* @len: the number of xmlChar
* @type: text or cdata
*
* receiving some chars from the parser.
* Append characters.
*/
void
xmlSAX2Characters(void *ctx, const xmlChar *ch, int len)
static void
xmlSAX2Text(xmlParserCtxtPtr ctxt, const xmlChar *ch, int len,
xmlElementType type)
{
xmlParserCtxtPtr ctxt = (xmlParserCtxtPtr) ctx;
xmlNodePtr lastChild;
if (ctx == NULL) return;
if (ctxt == NULL) return;
#ifdef DEBUG_SAX
xmlGenericError(xmlGenericErrorContext,
"SAX.xmlSAX2Characters(%.30s, %d)\n", ch, len);
@ -2535,7 +2536,10 @@ xmlSAX2Characters(void *ctx, const xmlChar *ch, int len)
* elements. Use an attribute in the structure !!!
*/
if (lastChild == NULL) {
lastChild = xmlSAX2TextNode(ctxt, ch, len);
if (type == XML_TEXT_NODE)
lastChild = xmlSAX2TextNode(ctxt, ch, len);
else
lastChild = xmlNewCDataBlock(ctxt->myDoc, ch, len);
if (lastChild != NULL) {
ctxt->node->children = lastChild;
ctxt->node->last = lastChild;
@ -2549,8 +2553,9 @@ xmlSAX2Characters(void *ctx, const xmlChar *ch, int len)
}
} else {
int coalesceText = (lastChild != NULL) &&
(lastChild->type == XML_TEXT_NODE) &&
(lastChild->name == xmlStringText);
(lastChild->type == type) &&
((type != XML_TEXT_NODE) ||
(lastChild->name == xmlStringText));
if ((coalesceText) && (ctxt->nodemem != 0)) {
/*
* The whole point of maintaining nodelen and nodemem,
@ -2607,7 +2612,10 @@ xmlSAX2Characters(void *ctx, const xmlChar *ch, int len)
}
} else {
/* Mixed content, first time */
lastChild = xmlSAX2TextNode(ctxt, ch, len);
if (type == XML_TEXT_NODE)
lastChild = xmlSAX2TextNode(ctxt, ch, len);
else
lastChild = xmlNewCDataBlock(ctxt->myDoc, ch, len);
if (lastChild != NULL) {
xmlAddChild(ctxt->node, lastChild);
if (ctxt->node->children != NULL) {
@ -2619,6 +2627,20 @@ xmlSAX2Characters(void *ctx, const xmlChar *ch, int len)
}
}
/**
* xmlSAX2Characters:
* @ctx: the user data (XML parser context)
* @ch: a xmlChar string
* @len: the number of xmlChar
*
* receiving some chars from the parser.
*/
void
xmlSAX2Characters(void *ctx, const xmlChar *ch, int len)
{
xmlSAX2Text((xmlParserCtxtPtr) ctx, ch, len, XML_TEXT_NODE);
}
/**
* xmlSAX2IgnorableWhitespace:
* @ctx: the user data (XML parser context)
@ -2775,27 +2797,7 @@ xmlSAX2Comment(void *ctx, const xmlChar *value)
void
xmlSAX2CDataBlock(void *ctx, const xmlChar *value, int len)
{
xmlParserCtxtPtr ctxt = (xmlParserCtxtPtr) ctx;
xmlNodePtr ret, lastChild;
if (ctx == NULL) return;
#ifdef DEBUG_SAX
xmlGenericError(xmlGenericErrorContext,
"SAX.pcdata(%.10s, %d)\n", value, len);
#endif
lastChild = xmlGetLastChild(ctxt->node);
#ifdef DEBUG_SAX_TREE
xmlGenericError(xmlGenericErrorContext,
"add chars to %s \n", ctxt->node->name);
#endif
if ((lastChild != NULL) &&
(lastChild->type == XML_CDATA_SECTION_NODE)) {
xmlTextConcat(lastChild, value, len);
} else {
ret = xmlNewCDataBlock(ctxt->myDoc, value, len);
if (xmlAddChild(ctxt->node, ret) == NULL)
xmlFreeNode(ret);
}
xmlSAX2Text((xmlParserCtxtPtr) ctx, value, len, XML_CDATA_SECTION_NODE);
}
static int xmlSAX2DefaultVersionValue = 2;