[master] cbb8bb437 Coverity polish: 1605323 Overflowed array index write

[Nils Goroll]

commit cbb8bb437b73ab51dedc78c4153a7243800d61d0
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Thu Sep 12 12:48:16 2024 +0200

    Coverity polish: 1605323 Overflowed array index write

diff --git a/bin/varnishd/mgt/mgt_jail_unix.c b/bin/varnishd/mgt/mgt_jail_unix.c
index c6cab790a..8fb6dfc9a 100644
--- a/bin/varnishd/mgt/mgt_jail_unix.c
+++ b/bin/varnishd/mgt/mgt_jail_unix.c
@@ -215,6 +215,7 @@ vju_subproc(enum jail_subproc_e jse)
 		/* Add the optional extra group for the C-compiler access */
 		i = getgroups(NGID, gid_list);
 		assert(i >= 0);
+		assert(i < NGID - 1);
 		gid_list[i++] = vju_cc_gid;
 		AZ(setgroups(i, gid_list));
 	}