From 50a8beedfe59f97d381e8f506344a6197b8b5702 Mon Sep 17 00:00:00 2001
From: Sergei Golubchik <serg@mariadb.org>
Date: Fri, 15 Sep 2017 15:02:24 +0200
Subject: [PATCH] MDEV-13708 Crash with indexed virtual columns and FK
 cascading deletes

InnoDB was too eager to forget the open table (m_mysql_table=NULL)
and that caused it to try to open a table which was opened by the user
not FK-prelocked. The server didn't expect that.

After fixing this, it crashed in gcol.innodb_virtual_fk test, trying to
compute virtual columns for a table that didn't have them. Because
row_upd_store_row() was deleting a row from node->table, while computing
virtual columns in thr->prebuilt->m_mysql_table. Which wasn't necessarily
the same table, and might've not even had virtual columns, even if
node->table did.
---
 mysql-test/suite/vcol/r/innodb_virtual_fk.result | 12 ++++++++++++
 mysql-test/suite/vcol/t/innodb_virtual_fk.test   | 16 ++++++++++++++++
 storage/innobase/row/row0mysql.cc                |  1 -
 storage/innobase/row/row0upd.cc                  |  3 ++-
 4 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100644 mysql-test/suite/vcol/r/innodb_virtual_fk.result
 create mode 100644 mysql-test/suite/vcol/t/innodb_virtual_fk.test

diff --git a/mysql-test/suite/vcol/r/innodb_virtual_fk.result b/mysql-test/suite/vcol/r/innodb_virtual_fk.result
new file mode 100644
index 00000000000..58db12583e2
--- /dev/null
+++ b/mysql-test/suite/vcol/r/innodb_virtual_fk.result
@@ -0,0 +1,12 @@
+set default_storage_engine=innodb;
+create table t1 (id int primary key, id2 int as (id) virtual, key id2 (id2));
+create table t2 (id int key, constraint fk_id foreign key (id) references t1 (id) on delete cascade);
+insert into t1 (id) values (1), (2);
+insert into t2 (id) values (1), (2);
+delete from t1;
+select * from t1;
+id	id2
+select * from t2;
+id
+drop table t2;
+drop table t1;
diff --git a/mysql-test/suite/vcol/t/innodb_virtual_fk.test b/mysql-test/suite/vcol/t/innodb_virtual_fk.test
new file mode 100644
index 00000000000..c364adaa613
--- /dev/null
+++ b/mysql-test/suite/vcol/t/innodb_virtual_fk.test
@@ -0,0 +1,16 @@
+source include/have_innodb.inc;
+set default_storage_engine=innodb;
+
+#
+# MDEV-13708 Crash with indexed virtual columns and FK cascading deletes
+#
+
+create table t1 (id int primary key, id2 int as (id) virtual, key id2 (id2));
+create table t2 (id int key, constraint fk_id foreign key (id) references t1 (id) on delete cascade);
+insert into t1 (id) values (1), (2);
+insert into t2 (id) values (1), (2);
+delete from t1;
+select * from t1;
+select * from t2;
+drop table t2;
+drop table t1;
diff --git a/storage/innobase/row/row0mysql.cc b/storage/innobase/row/row0mysql.cc
index 4ceef6c918f..4452960dbc9 100644
--- a/storage/innobase/row/row0mysql.cc
+++ b/storage/innobase/row/row0mysql.cc
@@ -2029,7 +2029,6 @@ run_again:
 		node->cascade_upd_nodes = cascade_upd_nodes;
 		cascade_upd_nodes->pop_front();
 		thr->fk_cascade_depth++;
-		prebuilt->m_mysql_table = NULL;
 
 		goto run_again;
 	}
diff --git a/storage/innobase/row/row0upd.cc b/storage/innobase/row/row0upd.cc
index 8ba3da255a4..a2be9a69a56 100644
--- a/storage/innobase/row/row0upd.cc
+++ b/storage/innobase/row/row0upd.cc
@@ -2966,7 +2966,8 @@ row_upd_del_mark_clust_rec(
 	entries */
 
 	row_upd_store_row(node, trx->mysql_thd,
-			  thr->prebuilt ? thr->prebuilt->m_mysql_table : NULL);
+			  thr->prebuilt  && thr->prebuilt->table == node->table
+			  ? thr->prebuilt->m_mysql_table : NULL);
 
 	/* Mark the clustered index record deleted; we do not have to check
 	locks, because we assume that we have an x-lock on the record */