From cd7a454c23f247c87f519cfd4c0199f3bc0cd731 Mon Sep 17 00:00:00 2001
From: Sergei Golubchik <serg@mariadb.org>
Date: Tue, 25 Mar 2025 11:11:01 +0100
Subject: [PATCH] MDEV-36351 MariaDB crashes when trying to access
 information_schema.users under --skip-grant-tables

---
 mysql-test/main/skip_grants.result | 16 +++++-----------
 mysql-test/main/skip_grants.test   | 17 ++++++-----------
 sql/sql_acl.cc                     |  5 +++++
 3 files changed, 16 insertions(+), 22 deletions(-)

diff --git a/mysql-test/main/skip_grants.result b/mysql-test/main/skip_grants.result
index 46e93cc79f3..b22f1545e81 100644
--- a/mysql-test/main/skip_grants.result
+++ b/mysql-test/main/skip_grants.result
@@ -68,19 +68,15 @@ count(*)
 select count(*) from information_schema.USER_PRIVILEGES;
 count(*)
 0
-#
 # End of 5.0 tests
 #
-#
 # Bug#29817 Queries with UDF fail with non-descriptive error
 # if mysql.proc is missing
 #
 select no_such_function(1);
 ERROR 42000: FUNCTION test.no_such_function does not exist
-#
 # End of 5.1 tests
 #
-#
 # MDEV-8280 crash in 'show global status' with --skip-grant-tables
 #
 show global status like 'Acl%';
@@ -96,17 +92,13 @@ Acl_role_grants	0
 Acl_roles	0
 Acl_table_grants	0
 Acl_users	0
-#
 # End of 10.1 tests
 #
-#
 # MDEV-22966 Server crashes or hangs with SET ROLE when started with skip-grant-tables
 #
 set role x;
 ERROR HY000: The MariaDB server is running with the --skip-grant-tables option so it cannot execute this statement
-#
 # End of 10.2 tests
-#
 show create user root@localhost;
 ERROR HY000: The MariaDB server is running with the --skip-grant-tables option so it cannot execute this statement
 insert mysql.global_priv values ('foo', 'bar', '{}');
@@ -134,10 +126,8 @@ CREATE USER `baz`@`baz` IDENTIFIED BY PASSWORD '*E52096EF8EB0240275A7FE9E069101C
 drop user bar@foo;
 drop user baz@baz;
 # restart
-#
 # End of 10.3 tests
 #
-#
 # MDEV-34501: SIGSEGV in pfs_start_mutex_wait_v1, __strlen_avx2, or __strlen_evex from safe_mutex_lock on CREATE DEFINER when using skip-grant-tables
 #
 CREATE DEFINER=a PROCEDURE p() SELECT 1;
@@ -156,6 +146,10 @@ SELECT @@skip_grant_tables AS EXPECT_0;
 EXPECT_0
 0
 # restart: --skip-grant-tables
-#
 # End of 10.10 tests
 #
+# MDEV-36351 MariaDB crashes when trying to access information_schema.users under --skip-grant-tables
+#
+select * from information_schema.users;
+USER	PASSWORD_ERRORS	PASSWORD_EXPIRATION_TIME
+# End of 11.8 tests
diff --git a/mysql-test/main/skip_grants.test b/mysql-test/main/skip_grants.test
index 228fa6459d8..a21e5c74d3e 100644
--- a/mysql-test/main/skip_grants.test
+++ b/mysql-test/main/skip_grants.test
@@ -104,9 +104,7 @@ select count(*) from information_schema.SCHEMA_PRIVILEGES;
 select count(*) from information_schema.TABLE_PRIVILEGES;
 select count(*) from information_schema.USER_PRIVILEGES;
 
---echo #
 --echo # End of 5.0 tests
---echo #
 
 --echo #
 --echo # Bug#29817 Queries with UDF fail with non-descriptive error
@@ -115,18 +113,14 @@ select count(*) from information_schema.USER_PRIVILEGES;
 --error ER_SP_DOES_NOT_EXIST
 select no_such_function(1);
 
---echo #
 --echo # End of 5.1 tests
---echo #
 
 --echo #
 --echo # MDEV-8280 crash in 'show global status' with --skip-grant-tables
 --echo #
 show global status like 'Acl%';
 
---echo #
 --echo # End of 10.1 tests
---echo #
 
 --echo #
 --echo # MDEV-22966 Server crashes or hangs with SET ROLE when started with skip-grant-tables
@@ -135,9 +129,7 @@ show global status like 'Acl%';
 --error ER_OPTION_PREVENTS_STATEMENT
 set role x;
 
---echo #
 --echo # End of 10.2 tests
---echo #
 
 #
 # MDEV-18297
@@ -164,9 +156,7 @@ drop user baz@baz;
 
 --enable_ps_protocol
 
---echo #
 --echo # End of 10.3 tests
---echo #
 
 --echo #
 --echo # MDEV-34501: SIGSEGV in pfs_start_mutex_wait_v1, __strlen_avx2, or __strlen_evex from safe_mutex_lock on CREATE DEFINER when using skip-grant-tables
@@ -194,6 +184,11 @@ SELECT @@skip_grant_tables AS EXPECT_0;
 --let $restart_parameters = --skip-grant-tables
 --source include/restart_mysqld.inc
 
---echo #
 --echo # End of 10.10 tests
+
 --echo #
+--echo # MDEV-36351 MariaDB crashes when trying to access information_schema.users under --skip-grant-tables
+--echo #
+select * from information_schema.users;
+
+--echo # End of 11.8 tests
diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index 1eba626cd4b..6f202317375 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -13127,7 +13127,12 @@ static int fill_users_schema_record(THD *thd, TABLE * table, ACL_USER *user)
 int fill_users_schema_table(THD *thd, TABLE_LIST *tables, COND *cond)
 {
   int res= 0;
+
 #ifndef NO_EMBEDDED_ACCESS_CHECKS
+  /* --skip-grants */
+  if (!initialized)
+    return res;
+
   bool see_whole_table= check_access(thd, SELECT_ACL, "mysql", NULL, NULL,
                                      true, true) == 0;
   TABLE *table= tables->table;