Hi Frank!
Thanks for report and investigation! Do you have a repro test
case that I can look at? Unfortunately, the ownership of the
DOM nodes is not trivial and I can't say for sure if this is
the right change or not.
Thank you in advance,
Aleksey
On 1/6/2010 5:21 AM, Frank Gross wrote:
Hi,
I had some random crashes using the xmlsec library for signature, so I
did a test with valgrind that reported an invalid read (see attached
valgrind output). You can see that it happens in the
'xmlXPathFreeNodeSet' function that is called in 'xmlSecNodeSetDestroy'.
After some investigations, I find out that it is related to the use of
an XPath transformation that builds a list of 'xmlSecNodeSetPtr' in the
'xmlSecXPathDataListExecute' function. In that function a new
'xmlSecNodeSetPtr' is added at the end of the list but containing the
nodes to be signed according to the XPath expression. Unfortunately, the
first 'xmlSecNodeSetPtr' of that list has the 'destroyDoc' boolean set
to 1 that tells the 'xmlSecNodeSetDestroy' function to release the whole
document, and when it is the next 'xmlSecNodeSetPtr' of the list to be
destroyed it tries to release the node resulting of the XPath
expression, but they don't exist anymore because the document they
belong to has been released just before.
To solve the problem I set the 'destroyDoc' of the first element to 0,
and put it to 1 on the last element of the list, so that the document is
only released at the very end. Actually, I simply add following code at
the end of the xmlSecXPathDataListExecute function just before the
return instruction.
...
if (res->destroyDoc) {
/* force the releasing of the document at the end of the list otherwise
xmlSecNodeSetDestroy can crash
because it will release the doc in the first node set but the following
ones have references to this document too
*/
res->destroyDoc = 0;
res->prev->destroyDoc = 1;
}
return(res);
...
I don't know if it is correct to do so or if there are some side effects
but it seems to fix my issue.
Regards,
Frank
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