Comment 0 for bug 1983100

Bionic's OpenSSL 1.1.1 package (https://launchpad.net/ubuntu/bionic/+source/openssl) is the only version of openssl 1.1.1 on any distro that we've encountered that does not have support for the OPENSSL_NO_ATEXIT functionality from 1.1.1b (openssl/openssl@c2b3db2).

The threading model in .NET has the possibility that background threads are still running when exit() is called, which can cause SIGSEGV if a background thread interacts with OpenSSL after/while it has unloaded. For that reason, we always initialize OpenSSL 1.1.1 with the OPENSSL_NO_ATEXIT flag (which, of all the distros we run on only has no effect on Bionic).

We feel that the stability of applications on Ubuntu 18.04 would be improved if the functionality of OPENSSL_NO_ATEXIT was merged into the bionic openssl 1.1.1 package, even if the constant isn't published into the header for the dev package.

Context: https://github.com/dotnet/runtime/issues/48411#issuecomment-1178405101