ipa-pwd-extop: fix memory leaks in ipapwd_pre_add()

In `ipapwd_pre_add()`, when processing password from entry extension,
`userpw` was reassigned without freeing the previous value.
Additionally, `enabled` obtained from `ipapwd_getIpaConfigAttr()` was
never freed, and early returns bypassed the cleanup section causing
memory leaks.

Free `userpw` before reassigning it.
Free `enabled` after use.
Replace early `return 0` statements with `goto done` to ensure proper
cleanup of all allocated resources.

Related: https://pagure.io/freeipa/issue/9895
Signed-off-by: Viktor Ashirov <vashirov@redhat.com>
Reviewed-By: Alexander Bokovoy <abbra@users.noreply.github.com>

daemons/ipa-slapi-plugins/ipa-pwd-extop/prepost.c

@@ -291,6 +291,7 @@ static int ipapwd_pre_add(Slapi_PBlock *pb)
                                   slapi_sdn_get_dn(sdn), errMesg);
                     goto done;
                 }
+                slapi_ch_free_string(&userpw);
                 userpw = slapi_ch_strdup(userpw_clear);
             }
 
@@ -302,8 +303,11 @@ static int ipapwd_pre_add(Slapi_PBlock *pb)
                 if (NULL == enabled) {
                     LOG("no ipaMigrationEnabled in config, assuming FALSE\n");
                 } else if (0 == strcmp(enabled, "TRUE")) {
-                    return 0;
+                    slapi_ch_free_string(&enabled);
+                    rc = LDAP_SUCCESS;
+                    goto done;
                 }
+                slapi_ch_free_string(&enabled);
 
                 /* With User Life Cycle, it could be a stage user that is activated.
                  * The userPassword and krb keys were set while the user was a stage user.
@@ -315,7 +319,8 @@ static int ipapwd_pre_add(Slapi_PBlock *pb)
                     LOG("User Life Cycle: %s is a activated stage user "
                         "(with prehashed password and krb keys)\n",
                         sdn ? slapi_sdn_get_dn(sdn) : "unknown");
-                    return 0;
+                    rc = LDAP_SUCCESS;
+                    goto done;
                 }
 
                 LOG("pre-hashed passwords are not valid\n");