From a7c43a684ac390636f2859dfe5cf65fb4be8f75b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vicen=C8=9Biu=20Ciorbaru?= <vicentiu@mariadb.org>
Date: Tue, 26 Jan 2016 14:49:25 +0200
Subject: [PATCH] MDEV-9304: MariaDB crash with specific query

tmp_join may get its tables freed twice during JOIN cleanup. Set them to NULL
when the tmp_join is different than the current join.
---
 sql/sql_union.cc | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/sql/sql_union.cc b/sql/sql_union.cc
index 87d3e86b2c7d5..95ce1c9b9404f 100644
--- a/sql/sql_union.cc
+++ b/sql/sql_union.cc
@@ -887,6 +887,12 @@ bool st_select_lex_unit::cleanup()
       join->tables_list= 0;
       join->table_count= 0;
       join->top_join_tab_count= 0;
+      if (join->tmp_join && join->tmp_join != join)
+      {
+        join->tmp_join->tables_list= 0;
+        join->tmp_join->table_count= 0;
+        join->tmp_join->top_join_tab_count= 0;
+      }
     }
     error|= fake_select_lex->cleanup();
     /*