Bug #22023218: MYSQL 5.5: MAIN.FULLTEXT HAS VALGRIND ISSUES.

Issue
-----
This problem occurs when varchar columns are used in a
internal temporary table. The type of the field is set
incorrectly to the generic FIELD_NORMAL type. This in turn
results in an inaccurate calculation of the record length.
Valgrind issues will occur since initialization has not
happend for some bytes.

Fix
----
While creating the temporary table, the type of the field
needs to be to set FIELD_VARCHAR. This will allow myisam
to calculate the record length accurately.

This fix is a backport of BUG#13350136.

sql/sql_select.cc

@@ -10313,8 +10313,8 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
   uint  temp_pool_slot=MY_BIT_NONE;
   uint fieldnr= 0;
   ulong reclength, string_total_length;
-  bool  using_unique_constraint= 0;
-  bool  use_packed_rows= 0;
+  bool  using_unique_constraint= false;
+  bool  use_packed_rows= false;
   bool  not_all_columns= !(select_options & TMP_TABLE_ALL_COLUMNS);
   char  *tmpname,path[FN_REFLEN];
   uchar	*pos, *group_buff, *bitmaps;
@@ -10370,10 +10370,10 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
     {
       (*tmp->item)->marker=4;			// Store null in key
       if ((*tmp->item)->max_length >= CONVERT_IF_BIGGER_TO_BLOB)
-	using_unique_constraint=1;
+	using_unique_constraint= true;
     }
     if (param->group_length >= MAX_BLOB_WIDTH)
-      using_unique_constraint=1;
+      using_unique_constraint= true;
     if (group)
       distinct=0;				// Can't use distinct
   }
@@ -10588,6 +10588,14 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
         *blob_field++= fieldnr;
 	blob_count++;
       }
+
+      if (new_field->real_type() == MYSQL_TYPE_STRING ||
+          new_field->real_type() == MYSQL_TYPE_VARCHAR)
+      {
+        string_count++;
+        string_total_length+= new_field->pack_length();
+      }
+
       if (item->marker == 4 && item->maybe_null)
       {
 	group_null_items++;
@@ -10638,7 +10646,7 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
     if (group &&
 	(param->group_parts > table->file->max_key_parts() ||
 	 param->group_length > table->file->max_key_length()))
-      using_unique_constraint=1;
+      using_unique_constraint= true;
   }
   else
   {
@@ -10791,6 +10799,10 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
              field->real_type() == MYSQL_TYPE_STRING &&
 	     length >= MIN_STRING_LENGTH_TO_PACK_ROWS)
       recinfo->type=FIELD_SKIP_ENDSPACE;
+    else if (use_packed_rows &&
+             field->real_type() == MYSQL_TYPE_VARCHAR &&
+             length >= MIN_STRING_LENGTH_TO_PACK_ROWS)
+      recinfo->type= FIELD_VARCHAR;
     else
       recinfo->type=FIELD_NORMAL;
     if (!--hidden_field_count)
@@ -11233,7 +11245,11 @@ static bool create_myisam_tmp_table(TABLE *table,TMP_TABLE_PARAM *param,
                        param->start_recinfo,
                        share->uniques, &uniquedef,
                        &create_info,
-		       HA_CREATE_TMP_TABLE)))
+                       HA_CREATE_TMP_TABLE |
+                       ((share->db_create_options & HA_OPTION_PACK_RECORD) ?
+                        HA_PACK_RECORD : 0)
+                      )))
+
   {
     table->file->print_error(error,MYF(0));	/* purecov: inspected */
     /*

storage/myisam/mi_create.c

 /*
-   Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
+   Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -462,7 +462,6 @@ int mi_create(const char *name,uint keys,MI_KEYDEF *keydefs,
     key_del[i]=HA_OFFSET_ERROR;
 
   unique_key_parts=0;
-  offset=reclength-uniques*MI_UNIQUE_HASH_LENGTH;
   for (i=0, uniquedef=uniquedefs ; i < uniques ; i++ , uniquedef++)
   {
     uniquedef->key=keys+i;
@@ -727,7 +726,7 @@ int mi_create(const char *name,uint keys,MI_KEYDEF *keydefs,
 #endif
   }
   /* Create extra keys for unique definitions */
-  offset=reclength-uniques*MI_UNIQUE_HASH_LENGTH;
+  offset=real_reclength - uniques * MI_UNIQUE_HASH_LENGTH;
   bzero((char*) &tmp_keydef,sizeof(tmp_keydef));
   bzero((char*) &tmp_keyseg,sizeof(tmp_keyseg));
   for (i=0; i < uniques ; i++)