MDEV-4277: Crash inside mi_killed_in_mariadb() with myisammrg

- Set MI_INFO::external_ref for MyISAM tables that are parts of myisamMRG table.

1 files changed, 14 insertions, 0 deletions

diff --git a/storage/myisammrg/ha_myisammrg.cc b/storage/myisammrg/ha_myisammrg.cc
index 274ba2fcd81..61fa32f86fe 100644
--- a/storage/myisammrg/ha_myisammrg.cc
+++ b/storage/myisammrg/ha_myisammrg.cc
@@ -422,6 +422,19 @@ static MI_INFO *myisammrg_attach_children_callback(void *callback_param)
   DBUG_RETURN(my_errno ? NULL : myisam);
 }
 
+/*
+  Set external_ref for the child MyISAM tables. They need this to be set in
+  order to check for killed status.
+*/
+static void myrg_set_external_ref(MYRG_INFO *m_info, void *ext_ref_arg)
+{
+  int i;
+  for (i= 0; i < (int)m_info->tables; i++)
+  {
+    m_info->open_tables[i].table->external_ref= ext_ref_arg;
+  }
+}
+
 
 /**
   @brief Open a MERGE parent table, not its children.
@@ -467,6 +480,7 @@ int ha_myisammrg::open(const char *name, int mode __attribute__((unused)),
     }
 
     file->children_attached= TRUE;
+    myrg_set_external_ref(file, (void*)table);
 
     info(HA_STATUS_NO_LOCK | HA_STATUS_VARIABLE | HA_STATUS_CONST);
   }