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Revert "Add support for parsing of large XML data (>= 10MB)" 

This reverts commit 2197d06224, following a discussion over a Coverity
report where issues like the "Billion laugh attack" could cause the
backend to waste CPU and memory even if a client applied checks on the
size of the data given in input, and libxml2 does not offer guarantees
that input limits are respected under XML_PARSE_HUGE.

Discussion: https://postgr.es/m/ZbHlgrPLtBZyr_QW@paquier.xyz
This commit is contained in:
Michael Paquier 2024-01-26 10:15:32 +09:00
parent 376c216138
commit f2743a7d70
3 changed files with 13 additions and 33 deletions
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4
contrib/xml2/xpath.c
View File

@ -381,7 +381,7 @@ pgxml_xpath(text *document, xmlChar *xpath, xpath_workspace *workspace)
{
workspace->doctree = xmlReadMemory((char *) VARDATA_ANY(document),
docsize, NULL, NULL,
XML_PARSE_HUGE | XML_PARSE_NOENT);
XML_PARSE_NOENT);
if (workspace->doctree != NULL)
{
workspace->ctxt = xmlXPathNewContext(workspace->doctree);
@ -626,7 +626,7 @@ xpath_table(PG_FUNCTION_ARGS)
if (xmldoc)
doctree = xmlReadMemory(xmldoc, strlen(xmldoc),
NULL, NULL,
XML_PARSE_HUGE | XML_PARSE_NOENT);
XML_PARSE_NOENT);
else /* treat NULL as not well-formed */
doctree = NULL;

4
contrib/xml2/xslt_proc.c
View File

@ -87,7 +87,7 @@ xslt_process(PG_FUNCTION_ARGS)
/* Parse document */
doctree = xmlReadMemory((char *) VARDATA_ANY(doct),
VARSIZE_ANY_EXHDR(doct), NULL, NULL,
XML_PARSE_HUGE | XML_PARSE_NOENT);
XML_PARSE_NOENT);
if (doctree == NULL)
xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
@ -96,7 +96,7 @@ xslt_process(PG_FUNCTION_ARGS)
/* Same for stylesheet */
ssdoc = xmlReadMemory((char *) VARDATA_ANY(ssheet),
VARSIZE_ANY_EXHDR(ssheet), NULL, NULL,
XML_PARSE_HUGE | XML_PARSE_NOENT);
XML_PARSE_NOENT);
if (ssdoc == NULL)
xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,

38
src/backend/utils/adt/xml.c
View File

@ -1688,8 +1688,8 @@ xml_doctype_in_content(const xmlChar *str)
* xmloption_arg, but a DOCTYPE node in the input can force DOCUMENT mode).
*
* If parsed_nodes isn't NULL and the input is not an XML document, the list
* of parsed nodes from the xmlParseInNodeContext call will be returned to
* *parsed_nodes.
* of parsed nodes from the xmlParseBalancedChunkMemory call will be returned
* to *parsed_nodes.
*
* Errors normally result in ereport(ERROR), but if escontext is an
* ErrorSaveContext, then "safe" errors are reported there instead, and the
@ -1795,7 +1795,7 @@ xml_parse(text *data, XmlOptionType xmloption_arg,
doc = xmlCtxtReadDoc(ctxt, utf8string,
NULL,
"UTF-8",
XML_PARSE_NOENT | XML_PARSE_DTDATTR | XML_PARSE_HUGE
XML_PARSE_NOENT | XML_PARSE_DTDATTR
| (preserve_whitespace ? 0 : XML_PARSE_NOBLANKS));
if (doc == NULL || xmlerrcxt->err_occurred)
{
@ -1828,30 +1828,10 @@ xml_parse(text *data, XmlOptionType xmloption_arg,
/* allow empty content */
if (*(utf8string + count))
{
const char *data;
xmlNodePtr root;
xmlNodePtr lst;
xmlParserErrors xml_error;
data = (const char *) (utf8string + count);
/*
* Create a fake root node. The xmlNewDoc() function creates
* an XML document without any nodes, and this is required for
* xmlParseInNodeContext() that is able to handle
* XML_PARSE_HUGE.
*/
root = xmlNewNode(NULL, (const xmlChar *) "content-root");
if (root == NULL || xmlerrcxt->err_occurred)
xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
"could not allocate xml node");
xmlDocSetRootElement(doc, root);
/* Try to parse string with using root node context. */
xml_error = xmlParseInNodeContext(root, data, strlen(data),
XML_PARSE_HUGE,
parsed_nodes ? parsed_nodes : &lst);
if (xml_error != XML_ERR_OK || xmlerrcxt->err_occurred)
res_code = xmlParseBalancedChunkMemory(doc, NULL, NULL, 0,
utf8string + count,
parsed_nodes);
if (res_code != 0 || xmlerrcxt->err_occurred)
{
xml_errsave(escontext, xmlerrcxt,
ERRCODE_INVALID_XML_CONTENT,
@ -4364,7 +4344,7 @@ xpath_internal(text *xpath_expr_text, xmltype *data, ArrayType *namespaces,
xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
"could not allocate parser context");
doc = xmlCtxtReadMemory(ctxt, (char *) string + xmldecl_len,
len - xmldecl_len, NULL, NULL, XML_PARSE_HUGE);
len - xmldecl_len, NULL, NULL, 0);
if (doc == NULL || xmlerrcxt->err_occurred)
xml_ereport(xmlerrcxt, ERROR, ERRCODE_INVALID_XML_DOCUMENT,
"could not parse XML document");
@ -4695,7 +4675,7 @@ XmlTableSetDocument(TableFuncScanState *state, Datum value)
PG_TRY();
{
doc = xmlCtxtReadMemory(xtCxt->ctxt, (char *) xstr, length, NULL, NULL, XML_PARSE_HUGE);
doc = xmlCtxtReadMemory(xtCxt->ctxt, (char *) xstr, length, NULL, NULL, 0);
if (doc == NULL || xtCxt->xmlerrcxt->err_occurred)
xml_ereport(xtCxt->xmlerrcxt, ERROR, ERRCODE_INVALID_XML_DOCUMENT,
"could not parse XML document");