MDEV-25925 Warning: Memory not freed: 32 on INSERT DELAYED

Also fixes MDEV-24467 Memory not freed after failed INSERT DELAYED

Description:

In case of an error (e.g. data truncation) during mysql_insert()
handling an INSERT DELAYED, the data type specific data in
fields (e.g. Field_blob::value) is not taken over by the delayed
writer thread.

All fields in table_list->table are freed by free_root()
immediately after mysql_insert(). To avoid a memory leak,
we need to free the specific data before exiting mysql_insert()
on error.

mysql-test/r/delayed_blob.result

+#
+# MDEV-25925 Warning: Memory not freed: 32 on INSERT DELAYED
+#
+SET sql_mode='TRADITIONAL';
+CREATE TABLE t1 (c BLOB) ENGINE=MyISAM;
+INSERT DELAYED INTO t1 VALUES (''||'');
+ERROR 22007: Truncated incorrect DOUBLE value: ''
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+#
+# MDEV-24467 Memory not freed after failed INSERT DELAYED
+#
+CREATE TABLE t1 (a VARCHAR(1)) ENGINE=MyISAM;
+ALTER TABLE t1 ADD b BLOB DEFAULT 'x';
+INSERT DELAYED INTO t1 (a) VALUES ('foo');
+ERROR 22001: Data too long for column 'a' at row 1
+DROP TABLE t1;

mysql-test/t/delayed_blob-master.opt

+--init_connect="set @a='something unique to have MTR start a dedicated mariadbd for this test and shutdown it after the test'"

mysql-test/t/delayed_blob.test

+--echo #
+--echo # MDEV-25925 Warning: Memory not freed: 32 on INSERT DELAYED
+--echo #
+
+SET sql_mode='TRADITIONAL';
+CREATE TABLE t1 (c BLOB) ENGINE=MyISAM;
+--error ER_TRUNCATED_WRONG_VALUE
+INSERT DELAYED INTO t1 VALUES (''||'');
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+
+
+--echo #
+--echo # MDEV-24467 Memory not freed after failed INSERT DELAYED
+--echo #
+
+CREATE TABLE t1 (a VARCHAR(1)) ENGINE=MyISAM;
+ALTER TABLE t1 ADD b BLOB DEFAULT 'x';
+--error ER_DATA_TOO_LONG
+INSERT DELAYED INTO t1 (a) VALUES ('foo');
+DROP TABLE t1;

sql/sql_insert.cc

@@ -1257,7 +1257,18 @@ bool mysql_insert(THD *thd,TABLE_LIST *table_list,
 abort:
 #ifndef EMBEDDED_LIBRARY
   if (lock_type == TL_WRITE_DELAYED)
+  {
     end_delayed_insert(thd);
+    /*
+      In case of an error (e.g. data truncation), the data type specific data
+      in fields (e.g. Field_blob::value) was not taken over
+      by the delayed writer thread. All fields in table_list->table
+      will be freed by free_root() soon. We need to free the specific
+      data before free_root() to avoid a memory leak.
+    */
+    for (Field **ptr= table_list->table->field ; *ptr ; ptr++)
+      (*ptr)->free();
+  }
 #endif
   if (table != NULL)
     table->file->ha_release_auto_increment();