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MDEV-23536 Race condition between KILL and transaction commit

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Server part:
  kill_handlerton() was accessing thd->ha_data[] for some other thd,
  while it could be concurrently modified by its owner thd.

  protect thd->ha_data[] modifications with a mutex.
  require this mutex when accessing thd->ha_data[] from kill_handlerton.

InnoDB part:
  on close_connection, detach trx from thd before freeing the trx
This commit is contained in:
Sergei Golubchik
2021-01-11 13:21:42 +01:00
parent 66f4900b51
commit 9b750dcbd8
3 changed files with 5 additions and 0 deletions
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3
sql/sql_class.cc
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@ -444,6 +444,7 @@ void thd_set_ha_data(THD *thd, const struct handlerton *hton,
const void *ha_data)
{
plugin_ref *lock= &thd->ha_data[hton->slot].lock;
DBUG_ASSERT(thd == current_thd);
if (ha_data && !*lock)
*lock= ha_lock_engine(NULL, (handlerton*) hton);
else if (!ha_data && *lock)
@ -451,7 +452,9 @@ void thd_set_ha_data(THD *thd, const struct handlerton *hton,
plugin_unlock(NULL, *lock);
*lock= NULL;
}
mysql_mutex_lock(&thd->LOCK_thd_data);
*thd_ha_data(thd, hton)= (void*) ha_data;
mysql_mutex_unlock(&thd->LOCK_thd_data);
}