Description of problem:
Upstream test suite, namely "BASIC Fail Second User" test is failing on s390x. No failures appear on x86_64, aarch64 or ppc64le.

--- Additional comment from Joe Orton on 2019-02-19 03:56:48 EST ---

mod_auth_gssapi is using:

    AP_INIT_FLAG("GssapiPublishErrors", ap_set_flag_slot,
                 (void *)APR_OFFSETOF(struct mag_config, enverrs), OR_AUTHCFG,
                 "Publish GSSAPI Errors in Envionment Variables"),

but enverrs is a bool:

    bool enverrs;

ap_set_flag_slot() requires a variable with sizeof(int) whereas it looks like sizeof(bool) is not fixed by C99, only "big enough to store one bit".  On x86_64 sizeof(bool) is sizeof(char) anyway, so it's broken everywhere.

The simplest fix would be to change envvers to type int.

--- Additional comment from Joe Orton on 2019-02-19 04:04:39 EST ---

The other use of ap_set_flag_slot in this module:

    AP_INIT_FLAG("GssapiImpersonate", ap_set_flag_slot,
          (void *)APR_OFFSETOF(struct mag_config, s4u2self), OR_AUTHCFG,
               "Do impersonation call (S4U2Self) "
               "based on already authentication username"),

also has the same problem; using either these directives may be splatting over other config fields in nasty ways depending on the struct padding.

--- Additional comment from Robbie Harwood on 2019-02-19 13:59:07 EST ---

Thanks Joe.  Posted fix upstream.