From b58586aae938e6aa7714c9bb3813da908e49010a Mon Sep 17 00:00:00 2001
From: Sergei Golubchik <serg@mariadb.org>
Date: Sat, 13 Jun 2020 12:49:22 +0200
Subject: [PATCH] MDEV-21560 Assertion `grant_table || grant_table_role' failed
 in check_grant_all_columns

With RETURNING it can happen that the user has some privileges on
the table (namely, DELETE), but later needs different privileges
on individual columns (namely, SELECT).

Do the same as in check_grant_column() - ER_COLUMNACCESS_DENIED_ERROR,
not an assert.
---
 mysql-test/main/grant5.result | 17 +++++++++++++++++
 mysql-test/main/grant5.test   | 17 +++++++++++++++++
 sql/sql_acl.cc                |  3 ++-
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/mysql-test/main/grant5.result b/mysql-test/main/grant5.result
index 43b58b82231..df09b1fcc64 100644
--- a/mysql-test/main/grant5.result
+++ b/mysql-test/main/grant5.result
@@ -225,4 +225,21 @@ drop user twg@'%';
 insert mysql.tables_priv (host,db,user,table_name,grantor,table_priv) values ('localhost','','otto','t1','root@localhost','select');
 flush privileges;
 delete from mysql.tables_priv where db='';
+create database db;
+create table db.t1 (a int);
+insert into db.t1 values (1);
+create user foo;
+grant delete on db.* to foo;
+connect  con1,localhost,foo,,;
+show create table db.t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` int(11) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+delete from db.t1 returning *;
+ERROR 42000: SELECT command denied to user 'foo'@'localhost' for column 'a' in table 't1'
+disconnect con1;
+connection default;
+drop database db;
+drop user foo;
 # End of 10.4 tests
diff --git a/mysql-test/main/grant5.test b/mysql-test/main/grant5.test
index 307549ec9d8..39fcff92435 100644
--- a/mysql-test/main/grant5.test
+++ b/mysql-test/main/grant5.test
@@ -182,4 +182,21 @@ insert mysql.tables_priv (host,db,user,table_name,grantor,table_priv) values ('l
 flush privileges;
 delete from mysql.tables_priv where db='';
 
+#
+# MDEV-21560 Assertion `grant_table || grant_table_role' failed in check_grant_all_columns
+#
+create database db;
+create table db.t1 (a int);
+insert into db.t1 values (1);
+create user foo;
+grant delete on db.* to foo;
+--connect (con1,localhost,foo,,)
+show create table db.t1;
+--error ER_COLUMNACCESS_DENIED_ERROR
+delete from db.t1 returning *;
+--disconnect con1
+--connection default
+drop database db;
+drop user foo;
+
 --echo # End of 10.4 tests
diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index 9ea69e5628b..8e17958a8a1 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -8335,7 +8335,8 @@ bool check_grant_all_columns(THD *thd, ulong want_access_arg,
 
         grant_table= grant->grant_table_user;
         grant_table_role= grant->grant_table_role;
-        DBUG_ASSERT (grant_table || grant_table_role);
+        if (!grant_table && !grant_table_role)
+          goto err;
       }
     }