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Fix low-probability memory leak in XMLSERIALIZE(... INDENT).

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xmltotext_with_options() did not consider the possibility that
pg_xml_init() could fail --- most likely due to OOM.  If that
happened, the already-parsed xmlDoc structure would be leaked.
Oversight in commit 483bdb2af.

Bug: #18981
Author: Dmitry Kovalenko <d.kovalenko@postgrespro.ru>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/18981-9bc3c80f107ae925@postgresql.org
Backpatch-through: 16
This commit is contained in:
Tom Lane
2025-07-08 12:50:19 -04:00
parent aa39b4e35a
commit e03c952877
1 changed files with 13 additions and 8 deletions
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21
src/backend/utils/adt/xml.c
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@ -532,7 +532,7 @@ xmltext(PG_FUNCTION_ARGS)
volatile xmlChar *xmlbuf = NULL; volatile xmlChar *xmlbuf = NULL;
PgXmlErrorContext *xmlerrcxt; PgXmlErrorContext *xmlerrcxt;
/* Otherwise, we gotta spin up some error handling. */ /* First we gotta spin up some error handling. */
xmlerrcxt = pg_xml_init(PG_XML_STRICTNESS_ALL); xmlerrcxt = pg_xml_init(PG_XML_STRICTNESS_ALL);
PG_TRY(); PG_TRY();
@ -685,7 +685,7 @@ xmltotext_with_options(xmltype *data, XmlOptionType xmloption_arg, bool indent)
volatile xmlBufferPtr buf = NULL; volatile xmlBufferPtr buf = NULL;
volatile xmlSaveCtxtPtr ctxt = NULL; volatile xmlSaveCtxtPtr ctxt = NULL;
ErrorSaveContext escontext = {T_ErrorSaveContext}; ErrorSaveContext escontext = {T_ErrorSaveContext};
PgXmlErrorContext *xmlerrcxt; PgXmlErrorContext *volatile xmlerrcxt = NULL;
#endif #endif
if (xmloption_arg != XMLOPTION_DOCUMENT && !indent) if (xmloption_arg != XMLOPTION_DOCUMENT && !indent)
@ -726,13 +726,18 @@ xmltotext_with_options(xmltype *data, XmlOptionType xmloption_arg, bool indent)
return (text *) data; return (text *) data;
} }
/* Otherwise, we gotta spin up some error handling. */ /*
xmlerrcxt = pg_xml_init(PG_XML_STRICTNESS_ALL); * Otherwise, we gotta spin up some error handling. Unlike most other
* routines in this module, we already have a libxml "doc" structure to
* free, so we need to call pg_xml_init() inside the PG_TRY and be
* prepared for it to fail (typically due to palloc OOM).
*/
PG_TRY(); PG_TRY();
{ {
size_t decl_len = 0; size_t decl_len = 0;
xmlerrcxt = pg_xml_init(PG_XML_STRICTNESS_ALL);
/* The serialized data will go into this buffer. */ /* The serialized data will go into this buffer. */
buf = xmlBufferCreate(); buf = xmlBufferCreate();
@ -863,10 +868,10 @@ xmltotext_with_options(xmltype *data, XmlOptionType xmloption_arg, bool indent)
xmlSaveClose(ctxt); xmlSaveClose(ctxt);
if (buf) if (buf)
xmlBufferFree(buf); xmlBufferFree(buf);
if (doc) xmlFreeDoc(doc);
xmlFreeDoc(doc);
pg_xml_done(xmlerrcxt, true); if (xmlerrcxt)
pg_xml_done(xmlerrcxt, true);
PG_RE_THROW(); PG_RE_THROW();
} }