BUG#48438 - crash with error in unioned query against merge

            table and view...

Invalid memory reads after a query referencing MyISAM table
multiple times with write lock. Invalid memory reads may
lead to server crash, valgrind warnings, incorrect values
in INFORMATION_SCHEMA.TABLES.{TABLE_ROWS, DATA_LENGTH,
INDEX_LENGTH, ...}.

This may happen when one of the table instances gets closed
after a query, e.g. out of slots in open tables cache. UNION,
MERGE and VIEW are irrelevant.

The problem was that MyISAM didn't restore state info
pointer to default value.

myisam/mi_locking.c

@@ -306,8 +306,8 @@ void mi_update_status(void* param)
 			    (long) info->s->state.state.data_file_length));
 #endif
     info->s->state.state= *info->state;
-    info->state= &info->s->state.state;
   }
+  info->state= &info->s->state.state;
   info->append_insert_at_end= 0;
 
   /*

mysql-test/r/myisam.result

@@ -1898,4 +1898,17 @@ CHECKSUM TABLE t1 EXTENDED;
 Table	Checksum
 test.t1	467455460
 DROP TABLE t1;
+#
+# BUG#48438 - crash with error in unioned query against merge table and view...
+#
+SET GLOBAL table_cache=3;
+CREATE TABLE t1(a INT);
+SELECT 1 FROM t1 AS a1, t1 AS a2, t1 AS a3, t1 AS a4 FOR UPDATE;
+1
+SELECT TABLE_ROWS, DATA_LENGTH FROM INFORMATION_SCHEMA.TABLES
+WHERE TABLE_SCHEMA='test' AND TABLE_NAME='t1';
+TABLE_ROWS	DATA_LENGTH
+0	0
+DROP TABLE t1;
+SET GLOBAL table_cache=DEFAULT;
 End of 5.0 tests

mysql-test/t/myisam.test

@@ -1239,4 +1239,15 @@ CHECKSUM TABLE t1 EXTENDED;
 DROP TABLE t1;
 
 
+--echo #
+--echo # BUG#48438 - crash with error in unioned query against merge table and view...
+--echo #
+SET GLOBAL table_cache=3;
+CREATE TABLE t1(a INT);
+SELECT 1 FROM t1 AS a1, t1 AS a2, t1 AS a3, t1 AS a4 FOR UPDATE;
+SELECT TABLE_ROWS, DATA_LENGTH FROM INFORMATION_SCHEMA.TABLES
+  WHERE TABLE_SCHEMA='test' AND TABLE_NAME='t1';
+DROP TABLE t1;
+SET GLOBAL table_cache=DEFAULT;
+
 --echo End of 5.0 tests