Calling xlst_process with certain arguments causes server crash

Hello,

It looks like calling xlst_process as follows causes a crash:

select xslt_process('<root xml_tb_version="2.0" type="struct" >
<ttm type="int32" >60</ttm>
<delta type="double" >0.75</delta>
<ttm2 type="int32" >30</ttm2>
<delta2 type="double" >0.75</delta2>
<expMonthNum type="int32" >1</expMonthNum>
<assetComb type="cell" >
<item type="char" >calendar spread</item>
</assetComb>
</root>','<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform&quot; version="1.0">
<xsl:output method="xml" indent="yes"/>

<xsl:template match="//root/*">
<elem type="{@type}" name="{name()}">
<xsl:value-of select="."/>
<xsl:attribute name="href">
result.asp?value=<xsl:value-of select="."/>
</xsl:attribute>
</elem>
</xsl:template>

</xsl:stylesheet>','')

After the crash pglog contains the following records:

2012-06-04 16:32:40.927 MSDLOG: server process (PID 4512) was terminated by exception 0xC0000005
2012-06-04 16:32:40.927 MSDHINT: See C include file "ntstatus.h" for a description of the hexadecimal value.
2012-06-04 16:32:40.927 MSDLOG: terminating any other active server processes

Could you please help to figure out how it can be fixed?

Thanks,
Peter

Peter Gagarinov | Head of Modelling and Analytics

Allied Testing

<pgagarinov@alliedtesting.com> writes:

It looks like calling xlst_process as follows causes a crash:

Hm, apparently xsltApplyStylesheet returns a NULL in this example,
and we're passing that on to xsltSaveResultToString which is not
expecting any such thing. I presume we need another error check
here, but what should the error say exactly? Can we get any info
more detailed than "failed to apply stylesheet"?

regards, tom lane

I wrote:

Hm, apparently xsltApplyStylesheet returns a NULL in this example,
and we're passing that on to xsltSaveResultToString which is not
expecting any such thing. I presume we need another error check
here, but what should the error say exactly? Can we get any info
more detailed than "failed to apply stylesheet"?

Apparently not -- or at least, if libxslt provides any easy way to
extract error reports, it's not evident from the pretty-awful
documentation. I've committed a fix that just reports "failed to apply
stylesheet".

regards, tom lane

Hello Tom,

Here is another example that causes a crash, probably for the same reason but better be safe than sorry:

select xslt_process('<root xml_tb_version="2.0" type="struct" >
<ttm type="int32" >60</ttm>
<delta type="double" >0.75</delta>
<ttm2 type="int32" >30</ttm2>
<delta2 type="double" >0.75</delta2>
<expMonthNum type="int32" >1</expMonthNum>
<assetComb type="cell" >
<item type="char" >calendar spread</item>
</assetComb>
</root>',
'<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform&quot; version="1.0">
<xsl:output method="xml" indent="yes"/>
<xsl:template match="root">
<xsl:for-each select="*">
<xsl:if test="item">
<elem type="{@type}" name="{global-name()}">
<xsl:value-of select="./item"/>
</elem>
<xsl:text>&#10;</xsl:text>
</xsl:if>
<xsl:if test="not(item)">
<elem type="{@type}" name="{name()}">
<xsl:value-of select="."/>
</elem>
<xsl:text>&#10;</xsl:text>
</xsl:if>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>','')

A correct error report for this case would be something like "function global-name is unknown" (I've just replaced a correct "name" function with "global-name") but of course "failed to apply stylesheet" is still better than a crash :)

Thanks,
Peter

Peter Gagarinov | Head of Modelling and Analytics

Allied Testing

-----Original Message-----
From: Tom Lane [mailto:tgl@sss.pgh.pa.us]
Sent: Tuesday, June 05, 2012 4:16 AM
To: Peter Gagarinov
Cc: pgsql-bugs@postgresql.org
Subject: Re: [BUGS] Calling xlst_process with certain arguments causes server crash

I wrote:

Hm, apparently xsltApplyStylesheet returns a NULL in this example, and
we're passing that on to xsltSaveResultToString which is not expecting
any such thing. I presume we need another error check here, but what
should the error say exactly? Can we get any info more detailed than
"failed to apply stylesheet"?

Apparently not -- or at least, if libxslt provides any easy way to extract error reports, it's not evident from the pretty-awful documentation. I've committed a fix that just reports "failed to apply stylesheet".

regards, tom lane