CVE: The DBD::mysql module through 4.043 for Perl allows remote attackers to cause a denial of service (use-after-free and application crash) or possibly have unspecified other impact by triggering (1) certain error responses from a MySQL server or (2) a loss of a network connection to a MySQL server. The use-after-free defect was introduced by relying on incorrect Oracle mysql_stmt_close documentation and code examples. From $URL: Hello! MySQL applications written according to Oracle's MySQL documentation & examples for mysql_stmt_close() function call are vulnerable to use- after-free defect. In mysql_stmt_close() documentation [1] for return value is written: "Zero for success. Nonzero if an error occurred." And there are defined two errors: CR_SERVER_GONE_ERROR CR_UNKNOWN_ERROR. From other parts of documentation can be understood that error messages for statements could be obtained by mysql_stmt_error() function [2]. Whole example of usage is written in mysql_stmt_execute() function [3]. The relevant part for mysql_stmt_close() is at the end of example: /* Close the statement */ if (mysql_stmt_close(stmt)) { fprintf(stderr, " failed while closing the statement\n"); fprintf(stderr, " %s\n", mysql_stmt_error(stmt)); exit(0); } And here is a problem, use-after-free defect. Current implementation of mysql_stmt_close() function unconditionally free passed statement structure and therefore following mysql_stmt_error() call is defective to use-after-free. Relevant part of implementation of mysql_stmt_close() function is: my_bool mysql_stmt_close(MYSQL_STMT *stmt) { int rc=0; ... if ((rc= stmt_command(mysql, COM_STMT_CLOSE, buff, 4, stmt))) set_stmt_errmsg(stmt, &mysql->net); ... my_free(stmt); return rc; } As you can see it stores real error message into stmt structure, but at the end it is freed. Which means error message is no longer available and caller is not able to read it (even via mysql_stmt_error() call). As such defective code is in example of the usage, probably couple of MySQL applications written according to that defective documentations are affected to this issue. There is reported real bug for MySQL DBI driver that is affected by this issue [4]. Reporter probably compiled MySQL library or driver itself with some compiler options which could detect buffer overflows and uncovered this issue. In April 17 I reported this issue to oCERT team and it was forwarded to MySQL, MariaDB and Percona security teams. MariaDB team answered that this is problem in Oracle & MySQL and their documentation as MariaDB do not have such vulnerable example in their documentation. Oracle team was unwilling to tell anything, provide any information how to handle such issue or what to do, therefore with suggestion from oCERT I decided to make this report public and open public discussion for other people on oss-security list how to handle this problem. As Oracle fully ignored this problem and have not stated if problem is in documentation, implementation or both, I see probably 3 different solutions: 1) Documentation with examples is correct and this is how it should be used. What is wrong is implementation. It would mean that function mysql_stmt_error() and mysql_stmt_errno() needs to specially handle statement pointers which were already freed by mysql_stmt_close(). This can be done e.g. by storing hash table of pointers and assigning for them last received error. Or clarifying that mysql_stmt_close() does not always free passed memory. Because from current description in documentation it is not fully unambiguous what happen if function fails. In this case implementation of mysql_stmt_close(), mysql_stmt_error() and mysql_stmt_errno() are vulnerable to use-after-free defect and needs to be fixed. And it should be assigned CVE for MySQL for this problem. 2) Implementation is correct, documentation is wrong. Documentation needs to be fixed to properly describe how are those functions implemented. Important note must be that if function mysql_stmt_close() fails it is not possible to take error code via mysql_stmt_error() or mysql_stmt_errno(). Also examples needs to be fixed. And then all MySQL applications which were written according to wrong documentation needs to be fixed and for each one needs to be assigned CVE. Number of those applications is unknown, to get it first every application which uses libmysqlclient.so needs to be checked and verified. What we know now is that MySQL Perl DBI is affected. 3) Documentation is wrong, but implementation of mysql_stmt_close() is not-so-correct. Which would mean that return value of mysql_stmt_close() is fully meaningless as there is no way to recover from bad state. Currently mysql_stmt_close() unconditionally free memory for statement, so no recover is possible. There are two options what can be done: * Always return value zero which means no error occurred. This basically mitigate use-after-free vulnerability in Oracle's documentation and also all applications which were written according to documentation. * When error occurred, do not free memory of passed structure. This would mean that following mysql_stmt_error() call would not be affected by use-after-free anymore. As Oracle ignored this security related problem (***) I would like to ask, how to handle this problem? And to which software needs to be requested for CVE? To MySQL itself (as described in option 1)? Or to every one software which uses MySQL (as described in option 2)? I think you understand me, that MySQL DBD driver needs to be fixed, ideally ASAP. Bug report on github is from April 13 [4]. And as Oracle is not willing to do anything, I hope that people on public oss-security list give some advice how to handle this situation. I'm CCing all relevant security teams, when replaying please do not forget to include them + me. Thanks! -- [1] - https://dev.mysql.com/doc/refman/5.7/en/mysql-stmt-close.html [2] - https://dev.mysql.com/doc/refman/5.7/en/mysql-stmt-error.html [3] - https://dev.mysql.com/doc/refman/5.7/en/mysql-stmt-execute.html [4] - https://github.com/perl5-dbi/DBD-mysql/issues/120 (***) - This is not a first time! Previous two security issues reported by me were ignored too. Oracle is the worst company in handling security issues. It is useless to report them anything. They just start threaten if you make information about issue public. And they are not competent to start working on it or fix it in less then 6 months! Really I suggest to not report any security bug to Oracle, it is just wasting of time.
Upstream seem to have no intent on fixing this in DBD-mysql: https://github.com/perl5-dbi/DBD-mysql/issues/120#issuecomment-359835586
I guess "seem" is the operative word, the referenced commit also was landed in master for 4.044. Yay. https://github.com/perl5-dbi/DBD-mysql/commit/79718cd69ec73203877bf7d13f0b8273e931f20f
The bug has been referenced in the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=0d845674dece9cded838f4184eeeaf33fea0a0ae commit 0d845674dece9cded838f4184eeeaf33fea0a0ae Author: Kent Fredric <kentnl@gentoo.org> AuthorDate: 2018-01-24 04:33:33 +0000 Commit: Kent Fredric <kentnl@gentoo.org> CommitDate: 2018-01-24 04:40:44 +0000 dev-perl/DBD-mysql: Bump to version 4.44.0 - Remove embedded support - https://bugs.gentoo.org/644174 - https://bugs.gentoo.org/598048 - removal from older versions may happen later Upstream: - Fix for CVE-2017-10788 ( https://bugs.gentoo.org/623632 ) - Fix for CVE-2017-10789 ( https://bugs.gentoo.org/623942 ) - Enforce SSL settings for BACKRONYM and Riddle - Fix parsing of mysql_config --libs output in Configure - Return INTs with ZEROFILL as strings - Some fixes for 5.26-dot-in-inc Bug: https://bugs.gentoo.org/598048 Bug: https://bugs.gentoo.org/623632 Bug: https://bugs.gentoo.org/623942 Bug: https://bugs.gentoo.org/644174 Package-Manager: Portage-2.3.18, Repoman-2.3.6 dev-perl/DBD-mysql/DBD-mysql-4.44.0.ebuild | 64 +++++++++ dev-perl/DBD-mysql/Manifest | 1 + .../DBD-mysql-4.044-amvis-type-conversions.patch | 56 ++++++++ .../files/DBD-mysql-4.044-no-dot-inc.patch | 151 +++++++++++++++++++++ 4 files changed, 272 insertions(+)}
GLSA Vote: No Cleanup will occur in bug #623942
