oss-sec mailing list archives
Use after free in libmysqlclient.so
From: pali () cpan org
Date: Fri, 27 Jan 2017 23:53:29 +0100
Hello, I would like to report problem related to MySQL/MariaDB and possibly asking for assigning CVE if this list is the right place. C client library for MySQL (libmysqlclient.so) has use-after-free defect which can cause crash of applications using that MySQL client. Defect occurs by calling mysql_close() function from libmysqlclient.so. If mysql_close() is called before calling all mysql_stmt_close() (for all allocated stmts), then following mysql_stmt_close() call try to write to already released memory. mysql_close() let dangling pointer exist for prepared statements. Real problem is in function mysql_prune_stmt_list() which incorrectly iterate over elements. Function list_add() overwrite ->next pointer of current element which overwrite next element for iteration. Basically it is just wrong usage of linked list structure. Languages in which is not guaranteed order of executing destructor of created objects have a big problem as such writing to memory pointed by dangling can cause crash of whole application. E.g. libmysqlclient.so used by perl DBD::mysql driver cause crash of whole perl process with simple script: perl -MDBI -e ' $dbh = DBI->connect("dbi:mysql:", "root", undef, {RaiseError => 1, mysql_server_prepare => 1}); $sth1 = $dbh->prepare("SELECT 1"); $sth2 = $dbh->prepare("USE mysql"); $dbh->disconnect; $dbh = undef; ' Segmentation fault Tested on amd64 Ubuntu 12.04 LTS with perl 5.14.2. To reproduce change username, password and host where is running mysql server. Valgrind can prove that memory corruption really occurs. This defect was fixed in MySQL 5.6.21 and MySQL 5.7.5 releases. But is present in all MySQL 5.5 versions (and also older) and appropriate older 5.6 and 5.7 versions. MySQL 5.5 is still used, supported and included in lot of linux distributions. Moreover this defect is present also in MariaDB releases. I tested all last major versions 10.2.3, 10.1.21, 10.0.29, 5.5.54 and all those are affected. MySQL and MariaDB provides also standalone package with only C client library libmysqlclient.so (without server) under name "Connector/C" and so appropriate versions of it are affected too. I found that this defected was fixed in MySQL git repository by commit: https://github.com/mysql/mysql-server/commit/4797ea0b772d5f4c5889bc552424132806f46e93 That commit can be easily applied to last MySQL 5.5.54 version and fixes this defect. Looks like problem was already reported and is publically available in MySQL bug tracker, see more details on links: https://bugs.mysql.com/bug.php?id=70429 https://bugs.mysql.com/bug.php?id=63363 (tickets are closed despite fact that MySQL 5.5 and older are not fixed) --- I reported this problem to Oracle secalert_us () oracle com two months ago, but they did absolutely nothing for fixing it in MySQL 5.5. Instead they started resending this problem to some random people with @cpan.org address for unknown reason. And told me to not disclose information about this defect. Resending does not look like normal handling of security related problem! Therefore I suggest other people to not wasting time reporting problems to Oracle for open source applications. As two months is really long time to fix such problem which was already fixed in new versions; it is already publically disclosed in MySQL bug tracker; fix available in public git; problem is in major MariaDB versions; fix is small; and this is open source product included in many linux distributions I decided to send information to oss-security.
Current thread:
- Use after free in libmysqlclient.so pali (Jan 27)
- Re: Use after free in libmysqlclient.so pali (Feb 10)
- Re: Use after free in libmysqlclient.so Solar Designer (Feb 10)
- Re: Use after free in libmysqlclient.so pali (Feb 11)
- Re: Re: Use after free in libmysqlclient.so pali (Feb 11)
- posting without being subscribed (was: Use after free in libmysqlclient.so) Solar Designer (Feb 11)
- Re: posting without being subscribed pali (Feb 11)
- Re: posting without being subscribed Solar Designer (Feb 11)
- Re: Use after free in libmysqlclient.so Solar Designer (Feb 10)
- Re: Use after free in libmysqlclient.so pali (Feb 10)