Re: CVE Request - MySQL - 5.0.88

[Sergei Golubchik <serg () mysql com>]

Hi, Jan!

On Nov 21, Jan Lieskovsky wrote:
> Hi Josh, Steve, vendors,
>
> MySQL upstream has released latest 5.0.88 version of their Community
> Server, fixing one security issue:
...
> While the other two (three issues) looks too to be security relevant:
>
> * Error handling was missing for SELECT statements containing
>   subqueries in the WHERE clause and that assigned a SELECT
>   result to a user variable. The server could crash as a result.
>   (Bug#48291: http://bugs.mysql.com/48291)
>
> This looks to be from adjacent network exploitable mysqld DoS.

Yes.

> * If the first argument to GeomFromWKB() function was a geometry
>   value, the function just returned its value. However, it
>   failed to preserve the argument's null_value flag, which
>   caused an unexpected NULL value to be returned to the caller,
>   resulting in a server crash.
>   (Bug#47780: http://bugs.mysql.com/47780)
>
> Same case as the above

Yes.

> * Failure to treat BIT values as unsigned could lead to
>   unpredictable results.
>  (Bug#42803: http://bugs.mysql.com/42803)
>
> Also this one seems to be security related - upstream bug speaks about
> invalid memory access and didn't check the code if this could lead to
> heap overflow once the comparison fails.


No, looks safe. It reads one byte and thinks it's a bool:

class Field_num ... { ...
   bool unsigned_flag;

while it's  somewhere in the middle of a pointer:

class Field_bit ... { ...
   uchar *bit_ptr;

The worst that can happen - MySQL could think the value is signed (BIT
values are always unsigned) and during the optimization phase won't
notice that the condition like "unsigned_value > negative_number" is
always true. Not a big deal.

Regards / Mit vielen Grüßen,
Sergei

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