auth: Unconditionally set pamh to NULL

Don't do it only in the successful case since the handle is
not useful afterwards and later calls might otherwise reuse the handle.

Also don't use the handle in the error path after pam_end.
Signed-off-by: Guido Günther <guido.gunther@puri.sm>

src/auth.c

@@ -94,11 +94,9 @@ authenticate (PhoshAuth *self, const gchar* number)
   }
 
   ret = pam_end(priv->pamh, ret);
-  if (ret == PAM_SUCCESS) {
+  if (ret != PAM_SUCCESS)
+    g_warning("pam_end error %d", ret);
   priv->pamh = NULL;
-  } else {
-    g_warning("pam_end error %s", pam_strerror (priv->pamh, ret));
-  }
 
  out:
   return authenticated;
@@ -165,7 +163,6 @@ phosh_auth_new (void)
 }
 
 
-
 void
 phosh_auth_authenticate_async_start (PhoshAuth           *self,
                                      const gchar         *number,