This afternoon I found that I couldn't run sudo in a way that worked last week.  Now, when 
a command is run, sudo would hang at startup. This is on a Solaris 7 machine, BTW.   
Doing some debugging, I found that sudo was sitting in a close() loop (seen below).  
Doing a search on Google, I found in the release notes for 1.6.2 that this was an issue on 
AIX if the limit for # of open files was "unlimited".  Sure enough, when I checked, "ulimit -
n" reported "unlimited".  If I set the number to an actual value, sudo ran the command 
without any hang as expected.

I can reproduce this repeatedly, and here's a summary of my test/debug procedure:

in one window:
(\#) \u@\h: \w $ uname -a
SunOS wile 5.7 Generic_106541-29 sun4u sparc SUNW,Ultra-250
(\#) \u@\h: \w $ sudo -l
User foo may run the following commands on this host:
    (root) NOPASSWD: ALL
(\#) \u@\h: \w $ ulimit -n      
unlimited                       
(\#) \u@\h: \w $ sudo uname -a
[hang]

from another window:
[ran ps|grep to find the sudo pid is 26995 in the first window]
$ sudo truss -p 26995
[...]
close(2116394580)                               Err#9 EBADF
close(2116394579)                               Err#9 EBADF
close(2116394578)                               Err#9 EBADF
close(2116394577)                               Err#9 EBADF
close(2116394576)                               Err#9 EBADF
close(2116394575)                               Err#9 EBADF
close(2116394574)                               Err#9 EBADF
close(2116394573)                               Err#9 EBADF
close(2116394572)                               Err#9 EBADF
close(2116394571)                               Err#9 EBADF
close(2116394570)                               Err#9 EBADF
close(2116394569)                               Err#9 EBADF
[...]
$ sudo kill 26995

back to first window: 
Terminated
(\#) \u@\h: \w $ (\#) \u@\h: \w $ ulimit -n 64
(\#) \u@\h: \w $ sudo uname -a
SunOS wile 5.7 Generic_106541-29 sun4u sparc SUNW,Ultra-250
(\#) \u@\h: \w $ sudo -V
Sudo version 1.6.7p5


I did several searches for the original bug for AIX/1.6.2, but couldn't find it, so I'm opening 
a new ticket about this.