Public bug reported: Hi,
Yesterday we upgraded from 5.7.29-0ubuntu0.18.04.1 to 5.7.30-0ubuntu0.18.04.1 (via unattended-upgrade) on Ubuntu 18.04 and slurmdbd (https://packages.ubuntu.com/bionic/admin/slurmdbd) started segfaulting. Upon inspection, the slurmdbd crash is caused by a change of behaviour of the SQL CONCAT function. The new behaviour seems wrong. Calling SELECT CONCAT(''); will result in an empty string as expected however if the result is assigned to a variable with: SET @var = ""; SELECT @var := CONCAT(''); the variable will be NULL instead of an empty string. It seems that when the output of CONCAT is assigned to a variable; if CONCAT should have returned an empty string, it will set the variable to NULL instead. SLURM itself crashes because it uses a stored procedure which relies on the output of CONCAT to be an empty string rather than a NULL variable and tries to dereference the pointer. I wasn’t able to get hold of 5.7.29-0ubuntu0.18.04.1 via APT so I tested on 5.7.21-1ubuntu1. On 5.7.21, the variable was correctly set to an empty string. I have also tried on 20.04 and the behaviour is correct as well. So the problem seems to be present only in the version 5.7.30-0ubuntu0.18.04.1. I think that the behaviour was introduced in the 5.7 branch by this commit: https://github.com/mysql/mysql-server/commit/addb2aab601d98e685eccae545f79d120561ad9b but I am not entirely sure. This bug is a bit annoying because it makes SLURM with accounting enabled completely unusable. However downgrading MySQL to 5.7.29-0ubuntu0.18.04.1 temporarily fixed the problem. I have attached a log file with examples to reproduce the bug. Thank you very much. ** Affects: mysql-5.7 (Ubuntu) Importance: Undecided Status: New ** Attachment added: "mysqlerror.txt" https://bugs.launchpad.net/bugs/1877442/+attachment/5367970/+files/mysqlerror.txt -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1877442 Title: Broken SQL CONCAT function behaviour in 5.7.30-0ubuntu0.18.04.1 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mysql-5.7/+bug/1877442/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
