diff --git a/mysql-test/r/mdl_sync.result b/mysql-test/r/mdl_sync.result
index 984f0df3d0e..8f236521f99 100644
--- a/mysql-test/r/mdl_sync.result
+++ b/mysql-test/r/mdl_sync.result
@@ -2381,3 +2381,17 @@ commit;
 # Reap ALTER TABLE.
 set debug_sync= 'RESET';
 drop table t1;
+#
+# Bug#52856 concurrent show columns or show full columns causes a crash!!!
+#
+CREATE TABLE t1(a CHAR(255));
+SET DEBUG_SYNC= "get_schema_column SIGNAL waiting WAIT_FOR completed";
+SHOW FULL COLUMNS FROM t1;
+SET DEBUG_SYNC= "now WAIT_FOR waiting";
+SHOW FULL COLUMNS FROM t1;
+Field	Type	Collation	Null	Key	Default	Extra	Privileges	Comment
+a	char(255)	latin1_swedish_ci	YES		NULL		select,insert,update,references	
+SET DEBUG_SYNC= "now SIGNAL completed";
+Field	Type	Collation	Null	Key	Default	Extra	Privileges	Comment
+a	char(255)	latin1_swedish_ci	YES		NULL		select,insert,update,references	
+DROP TABLE t1;
diff --git a/mysql-test/t/mdl_sync.test b/mysql-test/t/mdl_sync.test
index ef434e33cfa..dff29d2f6b6 100644
--- a/mysql-test/t/mdl_sync.test
+++ b/mysql-test/t/mdl_sync.test
@@ -3468,6 +3468,26 @@ connection default;
 set debug_sync= 'RESET';
 drop table t1;
 
+--echo #
+--echo # Bug#52856 concurrent show columns or show full columns causes a crash!!!
+--echo #
+CREATE TABLE t1(a CHAR(255));
+
+connect(con1, localhost, root);
+SET DEBUG_SYNC= "get_schema_column SIGNAL waiting WAIT_FOR completed";
+--send SHOW FULL COLUMNS FROM t1
+
+connection default;
+SET DEBUG_SYNC= "now WAIT_FOR waiting";
+SHOW FULL COLUMNS FROM t1;
+SET DEBUG_SYNC= "now SIGNAL completed";
+
+connection con1;
+--reap
+connection default;
+DROP TABLE t1;
+disconnect con1;
+
 
 # Check that all connections opened by test cases in this file are really
 # gone so execution of other tests won't be affected by their presence.
diff --git a/sql/sql_show.cc b/sql/sql_show.cc
index 00a507f0e47..07470ff4f42 100644
--- a/sql/sql_show.cc
+++ b/sql/sql_show.cc
@@ -18,6 +18,7 @@
 
 #include "my_global.h"                          /* NO_EMBEDDED_ACCESS_CHECKS */
 #include "sql_priv.h"
+#include "debug_sync.h"
 #include "unireg.h"
 #include "sql_acl.h"                        // fill_schema_*_privileges
 #include "sql_select.h"                         // For select_describe
@@ -3292,12 +3293,17 @@ static int fill_schema_table_from_frm(THD *thd, TABLE_LIST *tables,
     goto end_share;
   }
 
+  if (!open_table_from_share(thd, share, table_name->str, 0,
+                             (EXTRA_RECORD | OPEN_FRM_FILE_ONLY),
+                             thd->open_options, &tbl, FALSE))
   {
     tbl.s= share;
     table_list.table= &tbl;
     table_list.view= (LEX*) share->is_view;
     res= schema_table->process_table(thd, &table_list, table,
                                      res, db_name, table_name);
+    free_root(&tbl.mem_root, MYF(0));
+    my_free((char*) tbl.alias, MYF(MY_ALLOW_ZERO_PTR));
   }
 
 end_share:
@@ -4024,7 +4030,6 @@ static int get_schema_column_record(THD *thd, TABLE_LIST *tables,
   const char *wild= lex->wild ? lex->wild->ptr() : NullS;
   CHARSET_INFO *cs= system_charset_info;
   TABLE *show_table;
-  TABLE_SHARE *show_table_share;
   Field **ptr, *field, *timestamp_field;
   int count;
   DBUG_ENTER("get_schema_column_record");
@@ -4047,37 +4052,11 @@ static int get_schema_column_record(THD *thd, TABLE_LIST *tables,
   }
 
   show_table= tables->table;
-  show_table_share= show_table->s;
   count= 0;
-
-  if (tables->view || tables->schema_table)
-  {
-    ptr= show_table->field;
-    timestamp_field= show_table->timestamp_field;
-    show_table->use_all_columns();               // Required for default
-  }
-  else
-  {
-    ptr= show_table_share->field;
-    timestamp_field= show_table_share->timestamp_field;
-    /*
-      read_set may be inited in case of
-      temporary table
-    */
-    if (!show_table->read_set)
-    {
-      /* to satisfy 'field->val_str' ASSERTs */
-      uchar *bitmaps;
-      uint bitmap_size= show_table_share->column_bitmap_size;
-      if (!(bitmaps= (uchar*) alloc_root(thd->mem_root, bitmap_size)))
-        DBUG_RETURN(0);
-      bitmap_init(&show_table->def_read_set,
-                  (my_bitmap_map*) bitmaps, show_table_share->fields, FALSE);
-      bitmap_set_all(&show_table->def_read_set);
-      show_table->read_set= &show_table->def_read_set;
-    }
-    bitmap_set_all(show_table->read_set);
-  }
+  ptr= show_table->field;
+  timestamp_field= show_table->timestamp_field;
+  show_table->use_all_columns();               // Required for default
+  restore_record(show_table, s->default_values);
 
   for (; (field= *ptr) ; ptr++)
   {
@@ -4086,9 +4065,7 @@ static int get_schema_column_record(THD *thd, TABLE_LIST *tables,
     String type(tmp,sizeof(tmp), system_charset_info);
     char *end;
 
-    /* to satisfy 'field->val_str' ASSERTs */
-    field->table= show_table;
-    show_table->in_use= thd;
+    DEBUG_SYNC(thd, "get_schema_column");
 
     if (wild && wild[0] &&
         wild_case_compare(system_charset_info, field->field_name,wild))