From d3ff43852b22f5463d22aab390ef340d9ebe4b06 Mon Sep 17 00:00:00 2001
From: Peter Zhu <peter@peterzhu.ca>
Date: Thu, 29 Jun 2023 15:25:31 -0400
Subject: Fix memory leak in Hash#replace

Hash#replace can leak memory if the receiver has an ST table.
---
 hash.c                 | 15 ++++++++++++++-
 test/ruby/test_hash.rb |  2 +-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/hash.c b/hash.c
index a779c6f218..f3514cd94b 100644
--- a/hash.c
+++ b/hash.c
@@ -1158,6 +1158,19 @@ ar_clear(VALUE hash)
     }
 }
 
+static void
+st_free_and_clear_table(VALUE hash)
+{
+    HASH_ASSERT(RHASH_ST_TABLE_P(hash));
+
+    st_table *tab = RHASH_ST_TABLE(hash);
+
+    if (tab->bins != NULL) free(tab->bins);
+    free(tab->entries);
+
+    RHASH_ST_CLEAR(hash);
+}
+
 typedef int st_foreach_func(st_data_t, st_data_t, st_data_t);
 
 struct foreach_safe_arg {
@@ -2894,7 +2907,7 @@ rb_hash_replace(VALUE hash, VALUE hash2)
         ar_free_and_clear_table(hash);
     }
     else {
-        RHASH_ST_CLEAR(hash);
+        st_free_and_clear_table(hash);
     }
 
     hash_copy(hash, hash2);
diff --git a/test/ruby/test_hash.rb b/test/ruby/test_hash.rb
index e66beef29f..9121f3539e 100644
--- a/test/ruby/test_hash.rb
+++ b/test/ruby/test_hash.rb
@@ -1325,7 +1325,7 @@ class TestHash < Test::Unit::TestCase
   end
 
   def test_replace_memory_leak
-    assert_no_memory_leak([], "#{<<-"begin;"}", "#{<<-'end;'}")
+    assert_no_memory_leak([], "#{<<-"begin;"}", "#{<<-'end;'}", rss: true)
     h = ("aa".."zz").each_with_index.to_h
     10_000.times {h.dup}
     begin;
-- 
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