Prohibit circular causes [Bug #15447]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66510 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

eval.c

@@ -491,6 +491,7 @@ static inline VALUE
 exc_setup_message(const rb_execution_context_t *ec, VALUE mesg, VALUE *cause)
 {
     int nocause = 0;
+    int nocircular = 0;
 
     if (NIL_P(mesg)) {
 	mesg = ec->errinfo;
@@ -500,18 +501,32 @@ exc_setup_message(const rb_execution_context_t *ec, VALUE mesg, VALUE *cause)
     if (NIL_P(mesg)) {
 	mesg = rb_exc_new(rb_eRuntimeError, 0, 0);
 	nocause = 0;
+        nocircular = 1;
     }
     if (*cause == Qundef) {
 	if (nocause) {
 	    *cause = Qnil;
+            nocircular = 1;
 	}
 	else if (!rb_ivar_defined(mesg, id_cause)) {
 	    *cause = get_ec_errinfo(ec);
 	}
+        else {
+            nocircular = 1;
+        }
     }
     else if (!NIL_P(*cause) && !rb_obj_is_kind_of(*cause, rb_eException)) {
         rb_raise(rb_eTypeError, "exception object expected");
     }
+
+    if (!nocircular && !NIL_P(*cause) && *cause != Qundef && *cause != mesg) {
+        VALUE c = *cause;
+        while (!NIL_P(c = rb_attr_get(c, id_cause))) {
+            if (c == mesg) {
+                rb_raise(rb_eArgError, "circular causes");
+            }
+        }
+    }
     return mesg;
 }
 

test/ruby/test_exception.rb

@@ -1352,14 +1352,11 @@ $stderr = $stdout; raise "\x82\xa0"') do |outs, errs, status|
   end
 
   def test_circular_cause_handle
-    errs = [/.*error 1.*\n/, /.*error 2.*\n/, /.*error 1.*/m]
+    assert_raise_with_message(ArgumentError, /circular cause/) do
-    assert_in_out_err([], "#{<<~"begin;"}\n#{<<~'end;'}", [], errs, success: false, timeout: 2)
-    begin;
       begin
         raise "error 1"
       rescue => e1
-        raise "error 2" rescue e2 = $!
+        raise "error 2" rescue raise e1, cause: $!
-        raise e1, cause: e2
       end
     end;
   end