Use `irods::at_scope_exit` to free `RxComm::auth_scheme`

[alanking]

• [ ] main

• [ ] 4-3-stable

  The auth_scheme is copied into the comm object for the agent request step of the authentication flow as far back as 4.2.0: https://github.com/irods/irods/blob/f9c8c99c1188f92bc109da46f1eb2ca9e9ad9e04/plugins/auth/native/libnative.cpp#L297 https://github.com/irods/irods/blob/f9c8c99c1188f92bc109da46f1eb2ca9e9ad9e04/plugins/auth/pam/libpam.cpp#L378 https://github.com/irods/irods/blob/f9c8c99c1188f92bc109da46f1eb2ca9e9ad9e04/plugins/auth/osauth/libosauth.cpp#L326 https://github.com/irods/irods_auth_plugin_kerberos/blob/db961bf75615d8eefd497fe840d7494e106e2126/krb/libkrb.cpp#L1181

Please investigate whether this results in a leak.

[alanking]

I think I found the free call, so this might be close-able...

https://github.com/irods/irods/blob/e874106bbb1b67d7b59e7cbd112d37d200c2710a/server/core/src/rodsAgent.cpp#L593

[korydraughn]

Yes. That call to free() guards against a memory leak if everything works as expected.

Updating the code to use at_scope_exit would be better, but I don't think we need to address that for 4.2.12.

Bumping to 4.3.2 as this isn't an urgent issue.

[trel]

updated the checkboxes accordingly.