From 18fbb72f7db0728a178110b3c7d8bbaba5c8abad Mon Sep 17 00:00:00 2001
From: Zihao Mu <zihaomu@outlook.com>
Date: Mon, 31 Oct 2022 20:10:25 +0800
Subject: [PATCH] fix the infinite loop in tf importer.

---
 modules/dnn/src/tensorflow/tf_graph_simplifier.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/modules/dnn/src/tensorflow/tf_graph_simplifier.cpp b/modules/dnn/src/tensorflow/tf_graph_simplifier.cpp
index 72f546ead9..25ef850417 100644
--- a/modules/dnn/src/tensorflow/tf_graph_simplifier.cpp
+++ b/modules/dnn/src/tensorflow/tf_graph_simplifier.cpp
@@ -829,12 +829,19 @@ void RemoveIdentityOps(tensorflow::GraphDef& net)
             IdentityOpsMap::iterator it = identity_ops.find(input_op_name);
 
             if (it != identity_ops.end()) {
+                std::set<String> loopCheckSet;
                 // In case of Identity after Identity
                 while (true)
                 {
                     IdentityOpsMap::iterator nextIt = identity_ops.find(it->second);
                     if (nextIt != identity_ops.end())
+                    {
+                        // Loop check
+                        if (loopCheckSet.find(it->second) != loopCheckSet.end())
+                            CV_Error(Error::StsError, "Found a loop in your input Tensorflow model, which is illegal!");
+                        loopCheckSet.insert(it->second);
                         it = nextIt;
+                    }
                     else
                         break;
                 }