If one happens to create a driver object which has accidentally left out the kernel_version definition (note: at ld -r it gets declared as an external in symbol table!) then insmod core dumps when it tries to find out the kernel version for which the driver was compiled. It should check if the kernel_version symbol is defined as an external or not. If it is then complain and do nothing further.
This issue has been forwarded to a developer for further action.
insmod has no way of testing is a module is correct or not - it has to walk blindly in the object structure and read whatever is there.
sssd-1.16.2-4.fc28 has been submitted as an update to Fedora 28. https://bodhi.fedoraproject.org/updates/FEDORA-2018-5793dadb1d
sssd-1.16.2-4.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-2018-5793dadb1d
sssd-1.16.2-4.fc28 has been pushed to the Fedora 28 stable repository. If problems still persist, please make note of it in this bug report.