The sgetsgent function checks errno for ERANGE, but sgetsgent_r only returns ERANGE, but does not set errno to ERANGE. As a result, sgetsgent does not detect failure at all, and returns indicating success without filling in the struct sgrp result.

Upstream patch under review:

[PATCH] gshadow: Matching sgetsgent, sgetsgent_r ERANGE handling (bug 30151)
<https://sourceware.org/pipermail/libc-alpha/2023-February/145752.html>