segfault in mysql_server_end() from libmysqlclient.so.21

[JonHurst]

libmysqlclient.so.21 causes a segfault on shutdown.

Test case attached ==> "Removed database" will not be reported.

Backtrace:
#0 0x00007ffff14c330f in ?? () from /lib/x86_64-linux-gnu/libmysqlclient.so.21
#1 0x00007ffff14c8823 in ?? () from /lib/x86_64-linux-gnu/libmysqlclient.so.21
#2 0x00007ffff1466243 in mysql_server_end () from /lib/x86_64-linux-gnu/libmysqlclient.so.21
#3 0x00007ffff1b4d0ee in ?? () from /usr/lib/x86_64-linux-gnu/qt5/plugins/sqldrivers/libqsqlmysql.so
#4 0x00007ffff1b4d10d in ?? () from /usr/lib/x86_64-linux-gnu/qt5/plugins/sqldrivers/libqsqlmysql.so
#5 0x00007ffff78e55fb in ?? () from /lib/x86_64-linux-gnu/libQt5Sql.so.5
#6 0x00007ffff78e588e in QSqlDatabase::~QSqlDatabase() () from /lib/x86_64-linux-gnu/libQt5Sql.so.5
#7 0x00007ffff78e5d9c in ?? () from /lib/x86_64-linux-gnu/libQt5Sql.so.5
#8 0x0000555555555579 in cause_segfault () at main.cpp:16
#9 0x0000555555555729 in main (argc=1, argv=0x7fffffffeb18) at main.cpp:23

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: libqt5sql5-mysql 5.12.8+dfsg-0ubuntu1
ProcVersionSignature: Ubuntu 5.4.0-29.33-generic 5.4.30
Uname: Linux 5.4.0-29-generic x86_64
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: XFCE
Date: Wed May 6 21:40:58 2020
InstallationDate: Installed on 2020-04-27 (9 days ago)
InstallationMedia: Xubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
SourcePackage: qtbase-opensource-src
UpgradeStatus: No upgrade log present (probably fresh install)

[Lars Tangvald (lars-tangvald)]

Having trouble reproducing this:
$ ./test
About to remove database
Removed database

I don't know much about QT, so just did the bare minimum to get the test case built.

Did you build or run the test case in any particular way?

[JonHurst (jon-a-hursts)]

OK, disregard. I was using mariadb-server. After replacing it with mysql-server-8.0, I no longer get the segfault. Thanks for your help.

[Paul Harrison (mythtv-paulh)]

This bug also affects MythTV.

I can also reproduce this using the test app. You obviously need to point it to a valid server and database for the bug to trigger. I'll attach a slightly modified version of the test app that allows you to change the DB credentials to a valid host, user, password and database.

The bug started to trigger after an update to libmysqlclient21 from 8.0.17 to 8.0.20.

The server is Ubuntu Server 18.04.4 LTS.

The client is on Kbuntu 19.10.

[Paul Harrison (mythtv-paulh)]

Slightly modified test app

[Robie Basak (racb)]

@Paul

This bug report has been marked Invalid for reasons explained above. To avoid any further confusion, please file a separate bug with full steps to reproduce your problem, and please verify if you're using MySQL or MariaDB and file the bug against the appropriate package.

[Seth Arnold (seth-arnold)]

This may be the same issue as https://bugs.launchpad.net/ubuntu/+source/mysql-8.0/+bug/1877504

[Lars Tangvald (lars-tangvald)]

Right. This was reported first, but most of the discussion was there, so I'll mark this as a duplicate (as noted in the other report, this is a combination of a bug in mysql and maria still using mysql paths for incompatible files).

[Otto Kekäläinen (otto)]

The bug started to trigger after an update to libmysqlclient21 from 8.0.19 to 8.0.20. This is Oracle MySQL being backwards incompatible with any earlier version of MySQL or MariaDB. Please don't imply that the MariaDB packaging in any way caused this bug.