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Bug#30882 Dropping a temporary table inside a stored function may cause a server crash

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If a stored function that contains a drop temporary table statement
is invoked by a create temporary table of the same name may cause
a server crash. The problem is that when dropping a table no check
is done to ensure that table is not being used by some outer query
(or outer statement), potentially leaving the outer query with a
reference to a stale (freed) table.

The solution is when dropping a temporary table, always check if
the table is being used by some outer statement as a temporary
table can be dropped inside stored procedures.

The check is performed by looking at the TABLE::query_id value for
temporary tables. To simplify this check and to solve a bug related
to handling of temporary tables in prelocked mode, this patch changes
the way in which this member is used to track the fact that table is
used/unused. Now we ensure that TABLE::query_id is zero for unused
temporary tables (which means that all temporary tables which were
used by a statement should be marked as free for reuse after it's
execution has been completed).
This commit is contained in:
davi@endora.local
2007-11-01 18:52:56 -02:00
parent 6bd9f5c1cb
commit cc007acb78
15 changed files with 431 additions and 83 deletions
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4
sql/mysql_priv.h
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@ -679,7 +679,7 @@ extern my_decimal decimal_zero;
void free_items(Item *item);
void cleanup_items(Item *item);
class THD;
void close_thread_tables(THD *thd, bool locked=0, bool skip_derived=0);
void close_thread_tables(THD *thd);
bool check_one_table_access(THD *thd, ulong privilege, TABLE_LIST *tables);
bool check_single_table_access(THD *thd, ulong privilege,
TABLE_LIST *tables, bool no_errors);
@ -1419,7 +1419,7 @@ TABLE_LIST *unique_table(THD *thd, TABLE_LIST *table, TABLE_LIST *table_list,
bool check_alias);
TABLE *find_temporary_table(THD *thd, const char *db, const char *table_name);
TABLE *find_temporary_table(THD *thd, TABLE_LIST *table_list);
bool close_temporary_table(THD *thd, TABLE_LIST *table_list);
int drop_temporary_table(THD *thd, TABLE_LIST *table_list);
void close_temporary_table(THD *thd, TABLE *table, bool free_share,
bool delete_table);
void close_temporary(TABLE *table, bool free_share, bool delete_table);