Patches #925152, #1118602: Avoid reading after the end of the buffer

in pyexpat.GetInputContext. Will backport to 2.4.

Misc/NEWS

@@ -44,6 +44,9 @@ Core and builtins
 Extension Modules
 -----------------
 
+- Patches #925152, #1118602: Avoid reading after the end of the buffer
+  in pyexpat.GetInputContext.
+
 - Patches #749830, #1144555: allow UNIX mmap size to default to current 
   file size.
 

Modules/pyexpat.c

@@ -1082,7 +1082,7 @@ xmlparse_GetInputContext(xmlparseobject *self, PyObject *args)
                 = XML_GetInputContext(self->itself, &offset, &size);
 
             if (buffer != NULL)
-                result = PyString_FromStringAndSize(buffer + offset, size);
+                result = PyString_FromStringAndSize(buffer + offset, size - offset);
             else {
                 result = Py_None;
                 Py_INCREF(result);