mirror of
https://github.com/MariaDB/server.git
synced 2025-01-24 15:54:37 +01:00
MariaDB server is a community developed fork of MySQL server. Started by core members of the original MySQL team, MariaDB actively works with outside developers to deliver the most featureful, stable, and sanely licensed open SQL server in the industry.
amazon-web-servicesdatabasefulltext-searchgalerageographical-information-systeminnodbjsonmariadbmysqlrdbmsrelational-databasessqlstorage-enginevector-database
4bd94e7d1c
STRING CONVERSION FUNCTIONS
Problem:
While executing the prepared statement, user variable is
set to memory which would be freed at the end of
execution.
If the statement is executed again, valgrind throws
error when accessing this pointer.
Analysis:
1. First time when Item_func_set_user_var::check is called,
memory is allocated for "value" to store the result.
(In the call to copy_if_not_alloced).
2. While sending the result, Item_func_set_user_var::check
is called again. But, this time, its called with
"use_result_field" set to true.
As a result, we call result_field->val_str(&value).
3. Here memory allocated for "value" gets freed. And "value"
gets set to "result_field", with "str_length" being that of
result_field's.
4. In the call to JOIN::cleanup, result_field's memory gets
freed as this is allocated in a chunk as part of the
temporary table which is needed to execute the query.
5. Next time, when execute of the same statement is called,
"value" will be set to memory which is already freed.
Valgrind error occurs as "str_length" is positive
(set at Step 3)
Note that user variables list is stored as part of the Lex object
in set_var_list. Hence the persistance across executions.
Solution:
Patch for Bug#11764371 fixed in mysql-5.6+ fixes this problem
as well.So backporting the same.
In the solution for Bug#11764371, we create another object of
user_var and repoint it to temp_table's field. As a result while
deleting the alloced buffer in Step 3, since the cloned object
does not own the buffer, deletion will not happen.
So at step 5 when we execute the statement second time, the
original object will be used and since deletion did not happen
valgrind will not complain about dangling pointer.
sql/item_func.h:
Add constructors.
sql/sql_select.cc:
Change user variable assignment functions to read from fields after
tables have been unlocked.
|
||
|---|---|---|
| .bzr-mysql | ||
| BitKeeper | ||
| BUILD | ||
| client | ||
| cmd-line-utils | ||
| config/ac-macros | ||
| dbug | ||
| Docs | ||
| extra | ||
| include | ||
| libmysql | ||
| libmysql_r | ||
| libmysqld | ||
| man | ||
| mysql-test | ||
| mysys | ||
| netware | ||
| plugin | ||
| regex | ||
| scripts | ||
| server-tools | ||
| sql | ||
| sql-bench | ||
| sql-common | ||
| storage | ||
| strings | ||
| support-files | ||
| tests | ||
| unittest | ||
| vio | ||
| win | ||
| zlib | ||
| .bzrignore | ||
| .cvsignore | ||
| CMakeLists.txt | ||
| configure.in | ||
| COPYING | ||
| INSTALL-SOURCE | ||
| INSTALL-WIN-SOURCE | ||
| Makefile.am | ||
| README | ||
MySQL Server 5.1 This is a release of MySQL, a dual-license SQL database server. For the avoidance of doubt, this particular copy of the software is released under the version 2 of the GNU General Public License. MySQL is brought to you by Oracle. Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved. License information can be found in the COPYING file. MySQL FOSS License Exception We want free and open source software applications under certain licenses to be able to use specified GPL-licensed MySQL client libraries despite the fact that not all such FOSS licenses are compatible with version 2 of the GNU General Public License. Therefore there are special exceptions to the terms and conditions of the GPLv2 as applied to these client libraries, which are identified and described in more detail in the FOSS License Exception at <http://www.mysql.com/about/legal/licensing/foss-exception.html>. This distribution may include materials developed by third parties. For license and attribution notices for these materials, please refer to the documentation that accompanies this distribution (see the "Licenses for Third-Party Components" appendix) or view the online documentation at <http://dev.mysql.com/doc/>. GPLv2 Disclaimer For the avoidance of doubt, except that if any license choice other than GPL or LGPL is available it will apply instead, Oracle elects to use only the General Public License version 2 (GPLv2) at this time for any software where a choice of GPL license versions is made available with the language indicating that GPLv2 or any later version may be used, or where a choice of which version of the GPL is applied is otherwise unspecified. For further information about MySQL or additional documentation, see: - The latest information about MySQL: http://www.mysql.com - The current MySQL documentation: http://dev.mysql.com/doc Some Reference Manual sections of special interest: - If you are migrating from an older version of MySQL, please read the "Upgrading from..." section. - To see what MySQL can do, take a look at the features section. - For installation instructions, see the Installing and Upgrading chapter. - For the new features/bugfix history, see the MySQL Change History appendix. You can browse the MySQL Reference Manual online or download it in any of several formats at the URL given earlier in this file. Source distributions include a local copy of the manual in the Docs directory.