maria-developers team mailing list archive

[Sergei Golubchik <serg@xxxxxxxxxxx>]

Hi, Sanja!

On Apr 27, Oleksandr Byelkin wrote:
> revision-id: a7032fbb32d (mariadb-10.2.31-906-ga7032fbb32d)
> parent(s): b862377c3e9
> author: Oleksandr Byelkin <sanja@xxxxxxxxxxx>
> committer: Oleksandr Byelkin <sanja@xxxxxxxxxxx>
> timestamp: 2021-04-27 16:24:43 +0200
> message:
> 
> Bug#29363867: LOST CONNECTION TO MYSQL SERVER DURING QUERY
> 
> The problem is that sharing default expression among set instruction
> leads to attempt access result field of function created in
> other instruction runtime MEM_ROOT and already freed
> (a bit different then MySQL problem).
> 
> Fix is the same as in MySQL (but no optimisation for constant), turn
> DECLARE a, b, c type DEFAULT expr;
> to
> DECLARE a type DEFAULT expr, b type DEFAULT a, c type DEFAULT a;
> 
> diff --git a/mysql-test/t/sp.test b/mysql-test/t/sp.test
> index f13b3fbc281..007dfd1a10b 100644
> --- a/mysql-test/t/sp.test
> +++ b/mysql-test/t/sp.test
> @@ -10025,4 +10025,22 @@ DROP PROCEDURE p1;
>  DROP VIEW v1;
>  DROP TABLE t1;
>  
> +
> +--echo #
> +--echo #

forgot the bug summary (the first line of the commit comment)

> +--echo #
> +
> +delimiter |;
> +create function f1() returns bigint return now()-1|
> +create procedure p1()
> +begin
> +  declare b, c bigint default f1();
> +  select b-c;
> +end|
> +call p1()|
> +drop procedure p1|
> +drop function f1|
> +delimiter ;|
> +
> +
>  --echo #End of 10.2 tests
> diff --git a/sql/item.cc b/sql/item.cc
> index 42272fe0148..ec9f4ffb993 100644
> --- a/sql/item.cc
> +++ b/sql/item.cc
> @@ -2933,7 +2933,7 @@ bool Item_field::eq(const Item *item, bool binary_cmp) const
>  
>  table_map Item_field::used_tables() const
>  {
> -  if (field->table->const_table)
> +  if (!field || !field->table || field->table->const_table)

in what cases can field or field->table be NULL here?

>      return 0;					// const item
>    return (get_depended_from() ? OUTER_REF_TABLE_BIT : field->table->map);
>  }

Regards,
Sergei
VP of MariaDB Server Engineering
and security@xxxxxxxxxxx