Fixed bug #24653.

The bug report has demonstrated the following two problems.
1. If an ORDER/GROUP BY list includes a constant expression being 
optimized away and, at the same time, containing single-row
subselects that return more that one row, no error is reported.
Strictly speaking the standard allows to ignore error in this case.
Yet, now a corresponding fatal error is reported in this case.
2. If a query requires sorting by expressions containing single-row
subselects that, however, return more than one row, then the execution
of the query may cause a server crash. 
To fix this some code has been added that blocks execution of a subselect
item in case of a fatal error in the method Item_subselect::exec.

1 files changed, 4 insertions, 0 deletions

diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc
index 20a092d7607..cdbcde8b56b 100644
--- a/sql/item_subselect.cc
+++ b/sql/item_subselect.cc
@@ -39,6 +39,7 @@ Item_subselect::Item_subselect():
   engine(0), old_engine(0), used_tables_cache(0), have_to_be_excluded(0),
   const_item_cache(1), engine_changed(0), changed(0)
 {
+  with_subselect= 1;
   reset();
   /*
     item value is NULL if select_subselect not changed this value
@@ -201,6 +202,9 @@ bool Item_subselect::exec()
     mem root
   */
   thd->mem_root= &thd->main_mem_root;
+  if (thd->net.report_error)
+  /* Do not execute subselect in case of a fatal error */
+    return 1;
   res= engine->exec();
   thd->mem_root= old_root;