Re: Problem with "su -" and kernels 2.4.3-ac11 and higher

From: Ton Hospel (
Date: Wed Apr 25 2001 - 23:34:28 EST

In article <>,
        Alan Cox <> writes:
>> > Did you try nesting more than one "su -"? The first one after a boot
>> > works for me - every other one fails.
>> Same here: the first "su -" works OK, but a second nested one hangs:
> It appears to be a bug in PAM. Someone seems to reply on parent/child running
> order and just got caught out

I once debugged a very simular sounding problem that I solved with
the following patch to login. It's a wild guess, but you could try if
it happens to solve it. If not it might at least be a hint of what has to
be done to su.
(the problem is that the extra process PAM keeps waiting is process leader)
(I don't have redhat, so I can't check if this is relevant here)

diff -ur util-linux-2.9x/login-utils/login.c util-linux-2.9x-ton/login-utils/login.c
--- util-linux-2.9x/login-utils/login.c Sun Sep 12 23:25:30 1999
+++ util-linux-2.9x-ton/login-utils/login.c Tue Sep 21 03:24:52 1999
@@ -1109,6 +1112,15 @@
     /* child */
+ if (tcsetpgrp(0, getpid()) < 0)
+ fprintf(stderr,
+ _("login: could not become foreground process group: %s\n"),
+ strerror(errno));
+ if (setpgid(0, 0) < 0)
+ fprintf(stderr, _("login: could not become process leader: %s\n"),
+ strerror(errno));
     signal(SIGINT, SIG_DFL);
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This archive was generated by hypermail 2b29 : Mon Apr 30 2001 - 21:00:15 EST