From 810ae06c06312908fc1a7284773d8a9101ee145b Mon Sep 17 00:00:00 2001
From: nagachika <nagachika@ruby-lang.org>
Date: Sat, 25 Mar 2023 11:04:33 +0900
Subject: merge revision(s) 2e7e153a2af1456515d43b6381e38534b069b1c2: [Backport
 #19242]

	[Bug #19242] Prohibit circular causes to be loaded

	---
	 error.c                     |  4 ++++
	 eval.c                      |  4 ++++
	 eval_error.c                | 11 +++++++++++
	 test/ruby/test_exception.rb | 12 ++++++++++++
	 4 files changed, 31 insertions(+)
---
 error.c                     |  4 ++++
 eval.c                      |  4 ++++
 eval_error.c                | 11 +++++++++++
 test/ruby/test_exception.rb | 12 ++++++++++++
 version.h                   |  2 +-
 5 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/error.c b/error.c
index a870d0200b..65ad20a27b 100644
--- a/error.c
+++ b/error.c
@@ -2846,6 +2846,8 @@ ivar_copy_i(st_data_t key, st_data_t val, st_data_t exc)
     return ST_CONTINUE;
 }
 
+void rb_exc_check_circular_cause(VALUE exc);
+
 static VALUE
 exception_loader(VALUE exc, VALUE obj)
 {
@@ -2860,6 +2862,8 @@ exception_loader(VALUE exc, VALUE obj)
 
     rb_ivar_foreach(obj, ivar_copy_i, exc);
 
+    rb_exc_check_circular_cause(exc);
+
     if (rb_attr_get(exc, id_bt) == rb_attr_get(exc, id_bt_locations)) {
         rb_ivar_set(exc, id_bt_locations, Qnil);
     }
diff --git a/eval.c b/eval.c
index 0de3105ac7..97484b0b2a 100644
--- a/eval.c
+++ b/eval.c
@@ -528,12 +528,16 @@ exc_setup_message(const rb_execution_context_t *ec, VALUE mesg, VALUE *cause)
     }
 
     if (!nocircular && !NIL_P(*cause) && *cause != Qundef && *cause != mesg) {
+#if 0 /* maybe critical for some cases */
+        rb_exc_check_circular_cause(*cause);
+#else
         VALUE c = *cause;
         while (!NIL_P(c = rb_attr_get(c, id_cause))) {
             if (c == mesg) {
                 rb_raise(rb_eArgError, "circular causes");
             }
         }
+#endif
     }
     return mesg;
 }
diff --git a/eval_error.c b/eval_error.c
index 9b453eede0..1baa4484a0 100644
--- a/eval_error.c
+++ b/eval_error.c
@@ -310,6 +310,17 @@ show_cause(VALUE errinfo, VALUE str, VALUE highlight, VALUE reverse, long backtr
     }
 }
 
+void
+rb_exc_check_circular_cause(VALUE exc)
+{
+    VALUE cause = exc, shown_causes = 0;
+    do {
+        if (shown_cause_p(cause, &shown_causes)) {
+            rb_raise(rb_eArgError, "circular causes");
+        }
+    } while (!NIL_P(cause = rb_attr_get(cause, id_cause)));
+}
+
 void
 rb_error_write(VALUE errinfo, VALUE emesg, VALUE errat, VALUE str, VALUE highlight, VALUE reverse)
 {
diff --git a/test/ruby/test_exception.rb b/test/ruby/test_exception.rb
index f99bb230a3..ffca877f1e 100644
--- a/test/ruby/test_exception.rb
+++ b/test/ruby/test_exception.rb
@@ -1412,6 +1412,18 @@ $stderr = $stdout; raise "\x82\xa0"') do |outs, errs, status|
     end;
   end
 
+  def test_marshal_circular_cause
+    begin
+      raise RuntimeError, "err", [], cause: Exception.new
+    rescue => e
+    end
+    dump = Marshal.dump(e).sub(/o:\x0EException\x08;.0;.0;.0/, "@\x05")
+    assert_raise_with_message(ArgumentError, /circular cause/, ->{dump.inspect}) do
+      e = Marshal.load(dump)
+      assert_same(e, e.cause)
+    end
+  end
+
   def test_super_in_method_missing
     assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
     begin;
diff --git a/version.h b/version.h
index 5688813a20..6965efef46 100644
--- a/version.h
+++ b/version.h
@@ -11,7 +11,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 4
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 212
+#define RUBY_PATCHLEVEL 213
 
 #define RUBY_RELEASE_YEAR 2023
 #define RUBY_RELEASE_MONTH 3
-- 
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