From c168ba311228c523923f7ef7699cba96deedcc6d Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 27 Nov 2014 11:12:44 -0500
Subject: [PATCH] Free libxml2/libxslt resources in a safer order.
Mark Simonetti reported that libxslt sometimes crashes for him, and that
swapping xslt_process's object-freeing calls around to do them in reverse
order of creation seemed to fix it. I've not reproduced the crash, but
valgrind clearly shows a reference to already-freed memory, which is
consistent with the idea that shutdown of the xsltTransformContext is
trying to reference the already-freed stylesheet or input document.
With this patch, valgrind is no longer unhappy.
I have an inquiry in to see if this is a libxslt bug or if we're just
abusing the library; but even if it's a library bug, we'd want to adjust
our code so it doesn't fail with unpatched libraries.
Back-patch to all supported branches, because we've been doing this in
the wrong(?) order for a long time.
---
contrib/xml2/xslt_proc.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/contrib/xml2/xslt_proc.c b/contrib/xml2/xslt_proc.c
index 9f137873322..343924e9917 100644
--- a/contrib/xml2/xslt_proc.c
+++ b/contrib/xml2/xslt_proc.c
@@ -146,16 +146,16 @@ xslt_process(PG_FUNCTION_ARGS)
}
PG_CATCH();
{
- if (stylesheet != NULL)
- xsltFreeStylesheet(stylesheet);
if (restree != NULL)
xmlFreeDoc(restree);
- if (doctree != NULL)
- xmlFreeDoc(doctree);
- if (xslt_sec_prefs != NULL)
- xsltFreeSecurityPrefs(xslt_sec_prefs);
if (xslt_ctxt != NULL)
xsltFreeTransformContext(xslt_ctxt);
+ if (xslt_sec_prefs != NULL)
+ xsltFreeSecurityPrefs(xslt_sec_prefs);
+ if (stylesheet != NULL)
+ xsltFreeStylesheet(stylesheet);
+ if (doctree != NULL)
+ xmlFreeDoc(doctree);
xsltCleanupGlobals();
pg_xml_done(xmlerrcxt, true);
@@ -164,11 +164,11 @@ xslt_process(PG_FUNCTION_ARGS)
}
PG_END_TRY();
- xsltFreeStylesheet(stylesheet);
xmlFreeDoc(restree);
- xmlFreeDoc(doctree);
- xsltFreeSecurityPrefs(xslt_sec_prefs);
xsltFreeTransformContext(xslt_ctxt);
+ xsltFreeSecurityPrefs(xslt_sec_prefs);
+ xsltFreeStylesheet(stylesheet);
+ xmlFreeDoc(doctree);
xsltCleanupGlobals();
pg_xml_done(xmlerrcxt, false);
--
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