From 157c066f2b127d478291636b07f31872032486bf Mon Sep 17 00:00:00 2001
From: Howard Hinnant <howard.hinnant@gmail.com>
Date: Thu, 1 Nov 2018 16:17:11 -0400
Subject: [PATCH] Fix memory leak in Json move assignment operator

*  When move assignment is creates a cyclic ownership pattern
   memory was being leaked.  This patch breaks the cycle.

*  Fixes: #2572
---
 src/ripple/json/impl/json_value.cpp | 11 ++++++-----
 src/ripple/json/json_value.h        |  4 ++--
 src/test/json/json_value_test.cpp   | 12 ++++++++++++
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/src/ripple/json/impl/json_value.cpp b/src/ripple/json/impl/json_value.cpp
index 7fee5a95a8..88e0a429e9 100644
--- a/src/ripple/json/impl/json_value.cpp
+++ b/src/ripple/json/impl/json_value.cpp
@@ -348,10 +348,10 @@ Value::~Value ()
 }
 
 Value&
-Value::operator= ( const Value& other )
+Value::operator=(Value const& other)
 {
-    Value temp ( other );
-    swap ( temp );
+    Value tmp(other);
+    swap(tmp);
     return *this;
 }
 
@@ -365,9 +365,10 @@ Value::Value ( Value&& other ) noexcept
 }
 
 Value&
-Value::operator= ( Value&& other ) noexcept
+Value::operator=(Value&& other)
 {
-    swap ( other );
+    Value tmp(std::move(other));
+    swap(tmp);
     return *this;
 }
 
diff --git a/src/ripple/json/json_value.h b/src/ripple/json/json_value.h
index 1e5ca69109..242c22004b 100644
--- a/src/ripple/json/json_value.h
+++ b/src/ripple/json/json_value.h
@@ -233,10 +233,10 @@ public:
     Value ( const Value& other );
     ~Value ();
 
-    Value& operator= ( const Value& other );
+    Value& operator= ( Value const& other );
+    Value& operator= ( Value&& other );
 
     Value ( Value&& other ) noexcept;
-    Value& operator= ( Value&& other ) noexcept;
 
     /// Swap values.
     /// \note Currently, comments are intentionally not swapped, for
diff --git a/src/test/json/json_value_test.cpp b/src/test/json/json_value_test.cpp
index b20204d14a..82de38f473 100644
--- a/src/test/json/json_value_test.cpp
+++ b/src/test/json/json_value_test.cpp
@@ -296,6 +296,17 @@ struct json_value_test : beast::unit_test::suite
         }
     }
 
+  void
+    test_leak()
+    {
+      // When run with the address sanitizer, this test confirms there is no
+      // memory leak with the scenario below.
+      Json::Value a;
+      a[0u] = 1;
+      a = std::move(a[0u]);
+      pass();
+    }
+
     void run () override
     {
         test_bool ();
@@ -306,6 +317,7 @@ struct json_value_test : beast::unit_test::suite
         test_comparisons ();
         test_compact ();
         test_nest_limits ();
+        test_leak();
     }
 };