Re: atexit-handler causes segfault when dlopen-ed libldap is unloaded prior to program termination (ITS#1577)

[Kurt@OpenLDAP.org]

A preliminary fix is available in HEAD.
A workaround has also been made to OPENLDAP_REL_ENG_2
(disabled registration of atexit() routine).
Please test.

Kurt

At 01:23 AM 2002-02-04, argggh@linpro.no wrote:
>Full_Name: Arne Georg Gleditsch
>Version: 2.0.21
>OS: GNU/Linux
>URL: 
>Submission from: (NULL) (213.203.57.130)
>
>
>openldap-2.0.21/libraries/libldap/init.c contains the statement  
>"atexit(ldap_int_destroy_global_options)".  This causes programs
>that load and unload libldap using dlopen to segfault upon termination because
>one of the exit handlers reside in now unmapped memory.  Trivial example
>program:
>
>#include <stdio.h>
>#include <dlfcn.h>
>
>int main() {
>    void *(* ldap_init)(const char *, int);
>    void *ldap = NULL;
>    char *error;
>
>    void *handle = dlopen("libldap.so.2", RTLD_LAZY);
>
>    if (error = dlerror()) {
>        printf("%s\n", error);
>        exit();
>    }
>
>    ldap_init = dlsym(handle, "ldap_init");
>    if (error = dlerror()) {
>        printf("%s\n", error);
>        exit();
>    }
>
>    printf("libldap loaded.\n");
>
>    ldap_init("localhost", 389);
>
>    dlclose(handle);
>
>    printf("libldap unloaded.\n");
>}
>
>This is a real problem with pam-ldap, as su is now segfaulting at exit on my
>systems. Other services are likely affected as well.