Fix recursion counter check. Add control to override depth of nested … (#4953)

* Fix recursion counter check. Add control to override depth of nested objects.

* Change if-condition to `>=`

1 files changed, 9 insertions, 2 deletions

diff --git a/include/flatbuffers/idl.h b/include/flatbuffers/idl.h
index 63446247..cf5446a2 100644
--- a/include/flatbuffers/idl.h
+++ b/include/flatbuffers/idl.h
@@ -34,6 +34,12 @@
 // This file defines the data types representing a parsed IDL (Interface
 // Definition Language) / schema file.
 
+// Limits maximum depth of nested objects.
+// Prevents stack overflow while parse flatbuffers or json.
+#if !defined(FLATBUFFERS_MAX_PARSING_DEPTH)
+#  define FLATBUFFERS_MAX_PARSING_DEPTH 64
+#endif
+
 namespace flatbuffers {
 
 // The order of these matters for Is*() functions below.
@@ -745,10 +751,11 @@ class Parser : public ParserState {
   bool SupportsVectorOfUnions() const;
   Namespace *UniqueNamespace(Namespace *ns);
 
-  enum { kMaxParsingDepth = 64 };
   FLATBUFFERS_CHECKED_ERROR RecurseError();
   template<typename F> CheckedError Recurse(F f) {
-    if (++recurse_protection_counter >= kMaxParsingDepth) return RecurseError();
+    if (recurse_protection_counter >= (FLATBUFFERS_MAX_PARSING_DEPTH))
+      return RecurseError();
+    recurse_protection_counter++;
     auto ce = f();
     recurse_protection_counter--;
     return ce;