Bug#48157: crash in Item_field::used_tables

MySQL handles the join syntax "JOIN ... USING( field1,
... )" and natural joins by building the same parse tree as
a corresponding join with an "ON t1.field1 = t2.field1 ..."
expression would produce. This parse tree was not cleaned up
properly in the following scenario. If a thread tries to
lock some tables and finds that the tables were dropped and
re-created while waiting for the lock, it cleans up column
references in the statement by means a per-statement free
list. But if the statement was part of a stored procedure,
column references on the stored procedure's free list weren't
cleaned up and thus contained pointers to freed objects.

Fixed by adding a call to clean up the current prepared
statement's free list.


mysql-test/r/sp_sync.result:
  Bug#48157: Test case
mysql-test/t/sp_sync.test:
  Bug#48157: Test result
sql/item.h:
  Bug#48157: Commented field.
sql/sql_parse.cc:
  Bug#48157: Commented function.
sql/sql_update.cc:
  Bug#48157: fix

1 files changed, 23 insertions, 0 deletions

diff --git a/mysql-test/r/sp_sync.result b/mysql-test/r/sp_sync.result
new file mode 100644
index 00000000000..afa37e70531
--- /dev/null
+++ b/mysql-test/r/sp_sync.result
@@ -0,0 +1,23 @@
+Tests of syncronization of stored procedure execution.
+#
+# Bug#48157: crash in Item_field::used_tables
+#
+CREATE TABLE t1 AS SELECT 1 AS a, 1 AS b;
+CREATE TABLE t2 AS SELECT 1 AS a, 1 AS b;
+CREATE PROCEDURE p1()
+BEGIN
+UPDATE t1 JOIN t2 USING( a, b ) SET t1.b = 1, t2.b = 1;
+END|
+LOCK TABLES t1 WRITE, t2 WRITE;
+SET DEBUG_SYNC = 'multi_update_reopen_tables SIGNAL parked WAIT_FOR go';
+CALL p1();
+DROP TABLE t1, t2;
+SET DEBUG_SYNC = 'now WAIT_FOR parked';
+CREATE TABLE t1 AS SELECT 1 AS a, 1 AS b;
+CREATE TABLE t2 AS SELECT 1 AS a, 1 AS b;
+SET DEBUG_SYNC = 'now SIGNAL go';
+# Without the DEBUG_SYNC supplied in the same patch as this test in the 
+# code, this test statement will hang.
+DROP TABLE t1, t2;
+DROP PROCEDURE p1;
+SET DEBUG_SYNC = 'RESET';