slock provides its own definition of explicit_bzero, overriding the definition in glibc. It should use the glibc definition instead.
This bug appears to have been reported against 'rawhide' during the Fedora 26 development cycle. Changing version to '26'.
slock-1.4-8.fc28 has been submitted as an update to Fedora 28. https://bodhi.fedoraproject.org/updates/FEDORA-2018-4b943401e3
slock-1.4-8.fc28 has been pushed to the Fedora 28 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2018-4b943401e3
slock-1.4-8.fc28 has been pushed to the Fedora 28 stable repository. If problems still persist, please make note of it in this bug report.