double free or corruption (!prev)

[Will Bryant]

After switching from the MySQL client library to this MariaDB library, we and others have noticed sporadic crashes with the error "double free or corruption (!prev)" and a backtrace pointing to libmariadb.so.2. For us, the problem was more likely to occur when using a SELECT query with a large number of columns, but we have also observed it randomly at other times.

We use the Ruby mysql2 library, and others had already reported the crash there as https://github.com/brianmario/mysql2/issues/806, but since it doesn't occur with the normal mysql library they weren't making much headway.

But it turns out that the same crash (not involving Ruby) was however already reported upstream at https://mariadb.atlassian.net/browse/CONC-64, and was found to have the same root cause as https://mariadb.atlassian.net/browse/CONC-92.

That CONC-92 ticket includes a patch for the bug (https://mariadb.atlassian.net/secure/attachment/29803/mariadb-2.0.0-conc-92.patch), which was merged post 2.0.0.

I have manually applied this patch to the xenial source package and rebuilt, and I think it has fixed the issue for me.

So could this patch please be applied to the Xenial version of this package?

Zesty and Artful are on later versions of the library so should already have this fix.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Aaron Stone (sodabrew)]

As the maintainer of the mysql2 gem, I'm not able to work around this in the client application, it really needs to be fixed in the client library. Thanks for your attention!