Yuseok Jeon created XERCESC-2088:
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             Summary: Bad casting from DOMTextImpl to DOMElementImpl
                 Key: XERCESC-2088
                 URL: https://issues.apache.org/jira/browse/XERCESC-2088
             Project: Xerces-C++
          Issue Type: Bug
          Components: DOM
    Affects Versions: 3.1.4, 3.1.3, 3.1.2, 3.1.1
         Environment: ubuntu 16.04 LTS, Intel(R) Core(TM) i7-6700 CPU @ 
3.40GHz, 16GB
            Reporter: Yuseok Jeon
         Attachments: Actual_result.txt, relationship_tree.jpeg

Hi all, 

Our recently developed type confusion detection tool reports a type_confusion 
error in the "xercesc/dom/imple/DOMCasts.hpp" 

xercesc/dom/imple/DOMCasts.hpp, line 146

static inline DOMNodeImpl *castToNodeImpl(const DOMNode *p)
{
    DOMElementImpl *pE = (DOMElementImpl *)p;
    return &(pE->fNode);
}

p is pointing to the object allocated as DOMTextImpl, and it is casted into 
DOMElementImpl. However, since DOMElementImpl is not a subobject of 
DOMTextImpl, it is violating C++ standard rules 5.2.9/11--down casting is 
undefined if the object that the pointer to be casted points to is not a 
suboject of down casting type-- and causes undefined behaviors.

There are similar type-confusion cases as below links. 
 - (libstdc++) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60734
 - (Firefox) https://bugzilla.mozilla.org/show_bug.cgi?id=1074280

I attached a actual type confusion report and object relationship information. 



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