MDEV-18119 upgrading from 10.3 to 10.4 can result in the password for a user to be wiped out

10.1 part: SHOW CREATE USER didn't show the password, if plugin was set,
but authentication_string was not

1 files changed, 6 insertions, 2 deletions

diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index 784f2338a55..9d6e6c51fb6 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -986,8 +986,7 @@ static bool fix_user_plugin_ptr(ACL_USER *user)
   else
     return true;
 
-  if (user->auth_string.length)
-    set_user_salt(user, user->auth_string.str, user->auth_string.length);
+  set_user_salt(user, user->auth_string.str, user->auth_string.length);
   return false;
 }
 
@@ -1457,6 +1456,11 @@ static bool acl_load(THD *thd, TABLE_LIST *tables)
                                 safe_str(user.user.str),
                                 safe_str(user.host.hostname));
             }
+            else if (password_len)
+            {
+              user.auth_string.str= password;
+              user.auth_string.length= password_len;
+            }
 
             fix_user_plugin_ptr(&user);
           }