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Avoid regression in the size of XML input that we will accept.

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This mostly reverts commit 6082b3d5d, "Use xmlParseInNodeContext
not xmlParseBalancedChunkMemory".  It turns out that
xmlParseInNodeContext will reject text chunks exceeding 10MB, while
(in most libxml2 versions) xmlParseBalancedChunkMemory will not.
The bleeding-edge libxml2 bug that we needed to work around a year
ago is presumably no longer a factor, and the argument that
xmlParseBalancedChunkMemory is semi-deprecated is not enough to
justify a functionality regression.  Hence, go back to doing it
the old way.

Reported-by: Michael Paquier <michael@paquier.xyz>
Author: Michael Paquier <michael@paquier.xyz>
Co-authored-by: Erik Wienhold <ewie@ewie.name>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/aIGknLuc8b8ega2X@paquier.xyz
Backpatch-through: 13
This commit is contained in:
Tom Lane
2025-07-28 16:50:41 -04:00
parent 44e135ad57
commit 637ead2e1a
1 changed files with 30 additions and 38 deletions
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68
src/backend/utils/adt/xml.c
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@ -1730,7 +1730,7 @@ 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 we parse in CONTENT mode, the list
* of parsed nodes from the xmlParseInNodeContext call will be returned
* of parsed nodes from the xmlParseBalancedChunkMemory call will be returned
* to *parsed_nodes. (It is caller's responsibility to free that.)
*
* Errors normally result in ereport(ERROR), but if escontext is an
@ -1756,6 +1756,7 @@ xml_parse(text *data, XmlOptionType xmloption_arg,
PgXmlErrorContext *xmlerrcxt;
volatile xmlParserCtxtPtr ctxt = NULL;
volatile xmlDocPtr doc = NULL;
volatile int save_keep_blanks = -1;
/*
* This step looks annoyingly redundant, but we must do it to have a
@ -1783,7 +1784,6 @@ xml_parse(text *data, XmlOptionType xmloption_arg,
PG_TRY();
{
bool parse_as_document = false;
int options;
int res_code;
size_t count = 0;
xmlChar *version = NULL;
@ -1814,18 +1814,6 @@ xml_parse(text *data, XmlOptionType xmloption_arg,
parse_as_document = true;
}
/*
* Select parse options.
*
* Note that here we try to apply DTD defaults (XML_PARSE_DTDATTR)
* according to SQL/XML:2008 GR 10.16.7.d: 'Default values defined by
* internal DTD are applied'. As for external DTDs, we try to support
* them too (see SQL/XML:2008 GR 10.16.7.e), but that doesn't really
* happen because xmlPgEntityLoader prevents it.
*/
options = XML_PARSE_NOENT | XML_PARSE_DTDATTR
| (preserve_whitespace ? 0 : XML_PARSE_NOBLANKS);
/* initialize output parameters */
if (parsed_xmloptiontype != NULL)
*parsed_xmloptiontype = parse_as_document ? XMLOPTION_DOCUMENT :
@ -1835,11 +1823,26 @@ xml_parse(text *data, XmlOptionType xmloption_arg,
if (parse_as_document)
{
int options;
/* set up parser context used by xmlCtxtReadDoc */
ctxt = xmlNewParserCtxt();
if (ctxt == NULL || xmlerrcxt->err_occurred)
xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
"could not allocate parser context");
/*
* Select parse options.
*
* Note that here we try to apply DTD defaults (XML_PARSE_DTDATTR)
* according to SQL/XML:2008 GR 10.16.7.d: 'Default values defined
* by internal DTD are applied'. As for external DTDs, we try to
* support them too (see SQL/XML:2008 GR 10.16.7.e), but that
* doesn't really happen because xmlPgEntityLoader prevents it.
*/
options = XML_PARSE_NOENT | XML_PARSE_DTDATTR
| (preserve_whitespace ? 0 : XML_PARSE_NOBLANKS);
doc = xmlCtxtReadDoc(ctxt, utf8string,
NULL, /* no URL */
"UTF-8",
@ -1861,10 +1864,7 @@ xml_parse(text *data, XmlOptionType xmloption_arg,
}
else
{
xmlNodePtr root;
xmlNodePtr oldroot PG_USED_FOR_ASSERTS_ONLY;
/* set up document with empty root node to be the context node */
/* set up document that xmlParseBalancedChunkMemory will add to */
doc = xmlNewDoc(version);
if (doc == NULL || xmlerrcxt->err_occurred)
xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
@ -1877,36 +1877,23 @@ xml_parse(text *data, XmlOptionType xmloption_arg,
"could not allocate XML document");
doc->standalone = standalone;
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");
/*
* This attaches root to doc, so we need not free it separately;
* and there can't yet be any old root to free.
*/
oldroot = xmlDocSetRootElement(doc, root);
Assert(oldroot == NULL);
/* set parse options --- have to do this the ugly way */
save_keep_blanks = xmlKeepBlanksDefault(preserve_whitespace ? 1 : 0);
/* allow empty content */
if (*(utf8string + count))
{
xmlNodePtr node_list = NULL;
xmlParserErrors res;
res = xmlParseInNodeContext(root,
(char *) utf8string + count,
strlen((char *) utf8string + count),
options,
&node_list);
if (res != XML_ERR_OK || xmlerrcxt->err_occurred)
res_code = xmlParseBalancedChunkMemory(doc, NULL, NULL, 0,
utf8string + count,
&node_list);
if (res_code != 0 || xmlerrcxt->err_occurred)
{
xmlFreeNodeList(node_list);
xml_errsave(escontext, xmlerrcxt,
ERRCODE_INVALID_XML_CONTENT,
"invalid XML content");
xmlFreeNodeList(node_list);
goto fail;
}
@ -1922,6 +1909,8 @@ fail:
}
PG_CATCH();
{
if (save_keep_blanks != -1)
xmlKeepBlanksDefault(save_keep_blanks);
if (doc != NULL)
xmlFreeDoc(doc);
if (ctxt != NULL)
@ -1933,6 +1922,9 @@ fail:
}
PG_END_TRY();
if (save_keep_blanks != -1)
xmlKeepBlanksDefault(save_keep_blanks);
if (ctxt != NULL)
xmlFreeParserCtxt(ctxt);