MDEV-15834 The code in TABLE_SHARE::init_from_binary_frm_image() is not safe

mysql-test/suite/vcol/r/vcol_misc.result

@@ -354,5 +354,15 @@ a	b	c
 DROP TABLE t1;
 SET sql_mode=DEFAULT;
 #
+# MDEV-15834 The code in TABLE_SHARE::init_from_binary_frm_image() is not safe
+#
+SHOW TABLES;
+Tables_in_test
+t1
+SHOW CREATE TABLE t1;
+ERROR HY000: Incorrect information in file: './test/t1.frm'
+ALTER TABLE t1;
+ERROR HY000: Incorrect information in file: './test/t1.frm'
+#
 # End of 5.5 tests
 #

mysql-test/suite/vcol/t/vcol_misc.test

 --source include/have_ucs2.inc
 
+let $MYSQLD_DATADIR= `select @@datadir`;
+
 --disable_warnings
 drop table if exists t1,t2;
 --enable_warnings
@@ -318,6 +320,20 @@ SELECT * FROM t1;
 DROP TABLE t1;
 SET sql_mode=DEFAULT;
 
+
+--echo #
+--echo # MDEV-15834 The code in TABLE_SHARE::init_from_binary_frm_image() is not safe
+--echo #
+
+--copy_file std_data/frm/t1.frm $MYSQLD_DATADIR/test/t1.frm
+SHOW TABLES;
+--error ER_NOT_FORM_FILE
+SHOW CREATE TABLE t1;
+--error ER_NOT_FORM_FILE
+ALTER TABLE t1;
+--remove_file $MYSQLD_DATADIR/test/t1.frm
+
+
 --echo #
 --echo # End of 5.5 tests
 --echo #

sql/table.cc

@@ -1462,7 +1462,11 @@ static int open_binary_frm(THD *thd, TABLE_SHARE *share, uchar *head,
 
       if ((uchar)field_type == (uchar)MYSQL_TYPE_VIRTUAL)
       {
-        DBUG_ASSERT(interval_nr); // Expect non-null expression
+        if (!interval_nr) // Expect non-null expression
+        {
+          error= 4;
+          goto err;
+        }
         /* 
           The interval_id byte in the .frm file stores the length of the
           expression statement for a virtual column.