Fix XPath stack frame logic
Move the calls to xmlXPathSetFrame and xmlXPathPopFrame around in
xmlXPathCompOpEvalPositionalPredicate to make sure that the context
object on the stack is actually protected. Otherwise, memory corruption
can occur when calling sloppily coded XPath extension functions.
Fixes bug 783160.
diff --git a/xpath.c b/xpath.c
index 9481507..b816bd3 100644
--- a/xpath.c
+++ b/xpath.c
@@ -11932,11 +11932,11 @@
}
}
- frame = xmlXPathSetFrame(ctxt);
valuePush(ctxt, contextObj);
+ frame = xmlXPathSetFrame(ctxt);
res = xmlXPathCompOpEvalToBoolean(ctxt, exprOp, 1);
- tmp = valuePop(ctxt);
xmlXPathPopFrame(ctxt, frame);
+ tmp = valuePop(ctxt);
if ((ctxt->error != XPATH_EXPRESSION_OK) || (res == -1)) {
while (tmp != contextObj) {