Merge of fix for Bug#58207.

mysql-test/r/subselect4.result

@@ -164,6 +164,17 @@ a	b
 2	NULL
 DROP TABLE t1, t2, t3, t4, t5;
 #
+# Bug#58207: invalid memory reads when using default column value and 
+# tmptable needed
+#
+CREATE TABLE t(a VARCHAR(245) DEFAULT
+'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa');
+INSERT INTO t VALUES (''),(''),(''),(''),(''),(''),(''),(''),(''),(''),('');
+SELECT * FROM (SELECT default(a) FROM t GROUP BY a) d;
+default(a)
+aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+DROP TABLE t;
+#
 # End of 5.1 tests.
 #
 #

mysql-test/t/subselect4.test

@@ -136,6 +136,16 @@ SELECT * FROM t1 WHERE NULL NOT IN ( SELECT c FROM t2 WHERE c = 1 AND c <> 1 );
 
 DROP TABLE t1, t2, t3, t4, t5;
 
+--echo #
+--echo # Bug#58207: invalid memory reads when using default column value and 
+--echo # tmptable needed
+--echo #
+CREATE TABLE t(a VARCHAR(245) DEFAULT
+'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa');
+INSERT INTO t VALUES (''),(''),(''),(''),(''),(''),(''),(''),(''),(''),('');
+SELECT * FROM (SELECT default(a) FROM t GROUP BY a) d;
+DROP TABLE t;
+
 
 --echo #
 --echo # End of 5.1 tests.

sql/sql_select.cc

@@ -10042,7 +10042,12 @@ Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
                                           convert_blob_length);
     if (orig_type == Item::REF_ITEM && orig_modify)
       ((Item_ref*)orig_item)->set_result_field(result);
-    if (field->field->eq_def(result))
+    /*
+      Fields that are used as arguments to the DEFAULT() function already have
+      their data pointers set to the default value during name resulotion. See
+      Item_default_value::fix_fields.
+    */
+    if (orig_type != Item::DEFAULT_VALUE_ITEM && field->field->eq_def(result))
       *default_field= field->field;
     return result;
   }