improve ASAN instrumentation: table->record[0]

instrument table->record[0], table->record[1] and share->default_values.

One should not access record image beyond share->reclength, even
if table->record[0] has some unused space after it (functions that
work with records, might get a copy of the record as an argument,
and that copy - not being record[0] - might not have this buffer space
at the end). See b80fa400 and 444587d8

sql/table.cc

@@ -1269,9 +1269,10 @@ static int open_binary_frm(THD *thd, TABLE_SHARE *share, uchar *head,
   extra_rec_buf_length= uint2korr(head+59);
   rec_buff_length= ALIGN_SIZE(share->reclength + 1 + extra_rec_buf_length);
   share->rec_buff_length= rec_buff_length;
-  if (!(record= (uchar *) alloc_root(&share->mem_root,
-                                     rec_buff_length)))
+  if (!(record= (uchar *) alloc_root(&share->mem_root, rec_buff_length)))
     goto err;                          /* purecov: inspected */
+  MEM_NOACCESS(record, rec_buff_length);
+  MEM_UNDEFINED(record, share->reclength);
   share->default_values= record;
   if (mysql_file_pread(file, record, (size_t) share->reclength,
                        record_offset, MYF(MY_NABP)))
@@ -2430,6 +2431,7 @@ int open_table_from_share(THD *thd, TABLE_SHARE *share, const char *alias,
   if (!(record= (uchar*) alloc_root(&outparam->mem_root,
                                    share->rec_buff_length * records)))
     goto err;                                   /* purecov: inspected */
+  MEM_NOACCESS(record, share->rec_buff_length * records);
 
   if (records == 0)
   {
@@ -2444,6 +2446,8 @@ int open_table_from_share(THD *thd, TABLE_SHARE *share, const char *alias,
     else
       outparam->record[1]= outparam->record[0];   // Safety
   }
+  MEM_UNDEFINED(outparam->record[0], share->reclength);
+  MEM_UNDEFINED(outparam->record[1], share->reclength);
 
   if (!(field_ptr = (Field **) alloc_root(&outparam->mem_root,
                                           (uint) ((share->fields+1)*

storage/heap/ha_heap.cc

@@ -100,7 +100,15 @@ const char **ha_heap::bas_ext() const
 
 int ha_heap::open(const char *name, int mode, uint test_if_locked)
 {
-  set_if_bigger(table->s->reclength, sizeof (uchar*));
+  if (table->s->reclength < sizeof (char*))
+  {
+    MEM_UNDEFINED(table->s->default_values + table->s->reclength,
+                  sizeof(char*) - table->s->reclength);
+    table->s->reclength= sizeof(char*);
+    MEM_UNDEFINED(table->record[0], table->s->reclength);
+    MEM_UNDEFINED(table->record[1], table->s->reclength);
+  }
+
   internal_table= test(test_if_locked & HA_OPEN_INTERNAL_TABLE);
   if (internal_table || (!(file= heap_open(name, mode)) && my_errno == ENOENT))
   {