Index: mysql/mysql-test/r/view_grant.result
===================================================================
--- mysql.orig/mysql-test/r/view_grant.result
+++ mysql/mysql-test/r/view_grant.result
@@ -776,15 +776,59 @@ GRANT CREATE VIEW ON db26813.v2 TO u2681
 GRANT DROP, CREATE VIEW ON db26813.v3 TO u26813@localhost;
 GRANT SELECT ON db26813.t1 TO u26813@localhost;
 ALTER VIEW v1 AS SELECT f2 FROM t1;
-ERROR 42000: CREATE VIEW command denied to user 'u26813'@'localhost' for table 'v1'
+ERROR 42000: Access denied; you need the SUPER privilege for this operation
 ALTER VIEW v2 AS SELECT f2 FROM t1;
-ERROR 42000: DROP command denied to user 'u26813'@'localhost' for table 'v2'
+ERROR 42000: Access denied; you need the SUPER privilege for this operation
 ALTER VIEW v3 AS SELECT f2 FROM t1;
+ERROR 42000: Access denied; you need the SUPER privilege for this operation
 SHOW CREATE VIEW v3;
 View	Create View
-v3	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v3` AS select `t1`.`f2` AS `f2` from `t1`
+v3	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v3` AS select `t1`.`f1` AS `f1` from `t1`
 DROP USER u26813@localhost;
 DROP DATABASE db26813;
+#
+# Bug#29908: A user can gain additional access through the ALTER VIEW.
+#
+CREATE DATABASE mysqltest_29908;
+USE mysqltest_29908;
+CREATE TABLE t1(f1 INT, f2 INT);
+CREATE USER u29908_1@localhost;
+CREATE DEFINER = u29908_1@localhost VIEW v1 AS SELECT f1 FROM t1;
+CREATE DEFINER = u29908_1@localhost SQL SECURITY INVOKER VIEW v2 AS
+SELECT f1 FROM t1;
+GRANT DROP, CREATE VIEW, SHOW VIEW ON mysqltest_29908.v1 TO u29908_1@localhost;
+GRANT DROP, CREATE VIEW, SHOW VIEW ON mysqltest_29908.v2 TO u29908_1@localhost;
+GRANT SELECT ON mysqltest_29908.t1 TO u29908_1@localhost;
+CREATE USER u29908_2@localhost;
+GRANT DROP, CREATE VIEW ON mysqltest_29908.v1 TO u29908_2@localhost;
+GRANT DROP, CREATE VIEW, SHOW VIEW ON mysqltest_29908.v2 TO u29908_2@localhost;
+GRANT SELECT ON mysqltest_29908.t1 TO u29908_2@localhost;
+ALTER VIEW v1 AS SELECT f2 FROM t1;
+ERROR 42000: Access denied; you need the SUPER privilege for this operation
+ALTER VIEW v2 AS SELECT f2 FROM t1;
+SHOW CREATE VIEW v2;
+View	Create View
+v2	CREATE ALGORITHM=UNDEFINED DEFINER=`u29908_1`@`localhost` SQL SECURITY INVOKER VIEW `v2` AS select `t1`.`f2` AS `f2` from `t1`
+ALTER VIEW v1 AS SELECT f2 FROM t1;
+SHOW CREATE VIEW v1;
+View	Create View
+v1	CREATE ALGORITHM=UNDEFINED DEFINER=`u29908_1`@`localhost` SQL SECURITY DEFINER VIEW `v1` AS select `t1`.`f2` AS `f2` from `t1`
+ALTER VIEW v2 AS SELECT f1 FROM t1;
+SHOW CREATE VIEW v2;
+View	Create View
+v2	CREATE ALGORITHM=UNDEFINED DEFINER=`u29908_1`@`localhost` SQL SECURITY INVOKER VIEW `v2` AS select `t1`.`f1` AS `f1` from `t1`
+ALTER VIEW v1 AS SELECT f1 FROM t1;
+SHOW CREATE VIEW v1;
+View	Create View
+v1	CREATE ALGORITHM=UNDEFINED DEFINER=`u29908_1`@`localhost` SQL SECURITY DEFINER VIEW `v1` AS select `t1`.`f1` AS `f1` from `t1`
+ALTER VIEW v2 AS SELECT f2 FROM t1;
+SHOW CREATE VIEW v2;
+View	Create View
+v2	CREATE ALGORITHM=UNDEFINED DEFINER=`u29908_1`@`localhost` SQL SECURITY INVOKER VIEW `v2` AS select `t1`.`f2` AS `f2` from `t1`
+DROP USER u29908_1@localhost;
+DROP USER u29908_2@localhost;
+DROP DATABASE mysqltest_29908;
+#######################################################################
 DROP DATABASE IF EXISTS mysqltest1;
 DROP DATABASE IF EXISTS mysqltest2;
 CREATE DATABASE mysqltest1;
Index: mysql/mysql-test/t/view_grant.test
===================================================================
--- mysql.orig/mysql-test/t/view_grant.test
+++ mysql/mysql-test/t/view_grant.test
@@ -1034,10 +1034,11 @@ GRANT SELECT ON db26813.t1 TO u26813@loc
 
 connect (u1,localhost,u26813,,db26813);
 connection u1;
---error 1142
+--error ER_SPECIFIC_ACCESS_DENIED_ERROR
 ALTER VIEW v1 AS SELECT f2 FROM t1;
---error 1142
+--error ER_SPECIFIC_ACCESS_DENIED_ERROR
 ALTER VIEW v2 AS SELECT f2 FROM t1;
+--error ER_SPECIFIC_ACCESS_DENIED_ERROR
 ALTER VIEW v3 AS SELECT f2 FROM t1;
 
 connection root;
@@ -1047,6 +1048,50 @@ DROP USER u26813@localhost;
 DROP DATABASE db26813;
 disconnect u1;
 
+--echo #
+--echo # Bug#29908: A user can gain additional access through the ALTER VIEW.
+--echo #
+connection root;
+CREATE DATABASE mysqltest_29908;
+USE mysqltest_29908;
+CREATE TABLE t1(f1 INT, f2 INT);
+CREATE USER u29908_1@localhost;
+CREATE DEFINER = u29908_1@localhost VIEW v1 AS SELECT f1 FROM t1;
+CREATE DEFINER = u29908_1@localhost SQL SECURITY INVOKER VIEW v2 AS
+  SELECT f1 FROM t1;
+GRANT DROP, CREATE VIEW, SHOW VIEW ON mysqltest_29908.v1 TO u29908_1@localhost;
+GRANT DROP, CREATE VIEW, SHOW VIEW ON mysqltest_29908.v2 TO u29908_1@localhost;
+GRANT SELECT ON mysqltest_29908.t1 TO u29908_1@localhost;
+CREATE USER u29908_2@localhost;
+GRANT DROP, CREATE VIEW ON mysqltest_29908.v1 TO u29908_2@localhost;
+GRANT DROP, CREATE VIEW, SHOW VIEW ON mysqltest_29908.v2 TO u29908_2@localhost;
+GRANT SELECT ON mysqltest_29908.t1 TO u29908_2@localhost;
+
+connect (u2,localhost,u29908_2,,mysqltest_29908);
+--error ER_SPECIFIC_ACCESS_DENIED_ERROR
+ALTER VIEW v1 AS SELECT f2 FROM t1;
+ALTER VIEW v2 AS SELECT f2 FROM t1;
+SHOW CREATE VIEW v2;
+
+connect (u1,localhost,u29908_1,,mysqltest_29908);
+ALTER VIEW v1 AS SELECT f2 FROM t1;
+SHOW CREATE VIEW v1;
+ALTER VIEW v2 AS SELECT f1 FROM t1;
+SHOW CREATE VIEW v2;
+
+connection root;
+ALTER VIEW v1 AS SELECT f1 FROM t1;
+SHOW CREATE VIEW v1;
+ALTER VIEW v2 AS SELECT f2 FROM t1;
+SHOW CREATE VIEW v2;
+
+DROP USER u29908_1@localhost;
+DROP USER u29908_2@localhost;
+DROP DATABASE mysqltest_29908;
+disconnect u1;
+disconnect u2;
+--echo #######################################################################
+
 #
 # BUG#24040: Create View don't succed with "all privileges" on a database.
 #
Index: mysql/sql/sql_view.cc
===================================================================
--- mysql.orig/sql/sql_view.cc
+++ mysql/sql/sql_view.cc
@@ -224,9 +224,6 @@ bool mysql_create_view(THD *thd, TABLE_L
 {
   LEX *lex= thd->lex;
   bool link_to_local;
-#ifndef NO_EMBEDDED_ACCESS_CHECKS
-  bool definer_check_is_needed= mode != VIEW_ALTER || lex->definer;
-#endif
   /* first table in list is target VIEW name => cut off it */
   TABLE_LIST *view= lex->unlink_first_table(&link_to_local);
   TABLE_LIST *tables= lex->query_tables;
@@ -281,7 +278,7 @@ bool mysql_create_view(THD *thd, TABLE_L
       - same as current user
       - current user has SUPER_ACL
   */
-  if (definer_check_is_needed &&
+  if (lex->definer &&
       (strcmp(lex->definer->user.str, thd->security_ctx->priv_user) != 0 ||
        my_strcasecmp(system_charset_info,
                      lex->definer->host.str,