From 4635218cb07ee15244c7a6bbcf6eeeeb7cec7fcf Mon Sep 17 00:00:00 2001
From: Sergei Golubchik <serg@mariadb.org>
Date: Thu, 30 Jul 2020 10:01:49 +0200
Subject: [PATCH] MDEV-22521 Server crashes in traverse_role_graph_up or
 Assertion `user' fails in traverse_role_graph_impl

---
 mysql-test/suite/roles/drop_current_role.result | 5 +++++
 mysql-test/suite/roles/drop_current_role.test   | 9 +++++++++
 sql/sql_acl.cc                                  | 2 ++
 3 files changed, 16 insertions(+)
 create mode 100644 mysql-test/suite/roles/drop_current_role.result
 create mode 100644 mysql-test/suite/roles/drop_current_role.test

diff --git a/mysql-test/suite/roles/drop_current_role.result b/mysql-test/suite/roles/drop_current_role.result
new file mode 100644
index 00000000000..79525a0ff50
--- /dev/null
+++ b/mysql-test/suite/roles/drop_current_role.result
@@ -0,0 +1,5 @@
+create role r;
+set role r;
+drop role r;
+revoke all on *.* from current_role;
+ERROR 42000: There is no such grant defined for user 'r' on host ''
diff --git a/mysql-test/suite/roles/drop_current_role.test b/mysql-test/suite/roles/drop_current_role.test
new file mode 100644
index 00000000000..1485b830eed
--- /dev/null
+++ b/mysql-test/suite/roles/drop_current_role.test
@@ -0,0 +1,9 @@
+--source include/not_embedded.inc
+#
+# MDEV-22521 Server crashes in traverse_role_graph_up or Assertion `user' fails in traverse_role_graph_impl
+#
+create role r;
+set role r;
+drop role r;
+error ER_NONEXISTING_GRANT;
+revoke all on *.* from current_role;
diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index 7925ec58852..fee337925fc 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -4977,6 +4977,8 @@ static void propagate_role_grants(ACL_ROLE *role,
                                   enum PRIVS_TO_MERGE::what what,
                                   const char *db= 0, const char *name= 0)
 {
+  if (!role)
+    return;
 
   mysql_mutex_assert_owner(&acl_cache->lock);
   PRIVS_TO_MERGE data= { what, db, name };