clean up the depth tracking a bit

tinyxml2.cpp

@@ -2384,21 +2384,18 @@ void XMLDocument::Parse()
     ParseDeep(p, 0, &_parseCurLineNum );
 }
 
-bool XMLDocument::PushDepth()
+void XMLDocument::PushDepth()
 {
 	_parsingDepth++;
 	if (_parsingDepth == TINYXML2_MAX_ELEMENT_DEPTH) {
 		SetError(XMLError::XML_ELEMENT_DEPTH_EXCEEDED, _parseCurLineNum, "Element nesting is too deep." );
-		return false;
 	}
-	return true;
 }
 
-bool XMLDocument::PopDepth()
+void XMLDocument::PopDepth()
 {
 	TIXMLASSERT(_parsingDepth > 0);
 	--_parsingDepth;
-	return true;
 }
 
 XMLPrinter::XMLPrinter( FILE* file, bool compact, int depth ) :

tinyxml2.h

@@ -106,10 +106,12 @@ static const int TIXML2_PATCH_VERSION = 0;
 #define TINYXML2_MINOR_VERSION 1
 #define TINYXML2_PATCH_VERSION 0
 
-// This is problematic. There needs to be a limit to avoid a stack
-// overflow. However, that limit varies per system. Going with 
-// the MS value for now. May adjust in future versions.
-static const int TINYXML2_MAX_ELEMENT_DEPTH = 256;
+// A fixed element depth limit is problematic. There needs to be a 
+// limit to avoid a stack overflow. However, that limit varies per 
+// system, and the capacity of the stack. On the other hand, it's a trivial 
+// attack that can result from ill, malicious, or even correctly formed XML, 
+// so there needs to be a limit in place.
+static const int TINYXML2_MAX_ELEMENT_DEPTH = 100;
 
 namespace tinyxml2
 {
@@ -1915,8 +1917,8 @@ private:
 	private:
 		XMLDocument * _document;
 	};
-	bool PushDepth();
-	bool PopDepth();
+	void PushDepth();
+	void PopDepth();
 
     template<class NodeType, int PoolElementSize>
     NodeType* CreateUnlinkedNode( MemPoolT<PoolElementSize>& pool );

xmltest.cpp

@@ -2026,12 +2026,19 @@ int main( int argc, const char ** argv )
 	}
 
 	{
-		// Bad bad crash.
+		// Bad bad crash. Parsing error results in stack overflow, if uncaught.
+		const char* TESTS[] = {
+			"./resources/xmltest-5330.xml",
+			"./resources/xmltest-4636783552757760.xml",
+			"./resources/xmltest-5720541257269248.xml",
+			0
+		};
+		for (int i=0; TESTS[i]; ++i) {
 			XMLDocument doc;
-		doc.LoadFile("./resources/xmltest-5330.xml");
+			doc.LoadFile(TESTS[i]);
 			XMLTest("Stack overflow prevented.", XMLError::XML_ELEMENT_DEPTH_EXCEEDED, doc.ErrorID());
 		}
-
+	}
 	{
 		// Crashing reported via email.
 		const char* xml =