Bug 927

Summary:	sudo 1.9.0 on AIX: Terminal input/output very sluggish when "log_output" is enabled
Product:	Sudo	Reporter:	altmark
Component:	Sudo	Assignee:	Todd C. Miller <Todd.Miller>
Status:	RESOLVED FIXED
Severity:	normal
Priority:	low
Version:	1.9.0
Hardware:	IBM
OS:	AIX

Description altmark 2020-05-12 08:09:17 MDT

After updating to sudo 1.9.0 today, I found that the terminal input and output within a new session is very sluggish.

The characters I type appear with a noticable delay on the screen and sometimes a command's output does not show up after the first press of the <Return> key, only after 2-3 more keypress events or even when entering the next command.

This seems to be related to I/O logging, since the issue is gone when I comment or remove the

  Defaults log_output

line in /etc/sudoers.

I've tried the RPM package for AIX 7.1 and above from https://www.sudo.ws/download.html#binary as well as building sudo from source myself - same behaviour.

Also ran it on different systems, one with AIX 7100-05-05, the other with AIX 7200-04-01. The problem occurs on both.

Comment 1 Todd C. Miller 2020-05-12 08:20:39 MDT

What version of sudo were you running previously?

Comment 2 altmark 2020-05-12 08:29:10 MDT

Sorry, should have noted that. I've updated from 1.8.31p1 which was working fine. The configuration files have been unchanged.

Comment 3 Todd C. Miller 2020-05-12 09:07:21 MDT

sudo 1.9.0 will use the cfmakeraw() function to set the pty to raw mode if it is available.  This function exists on AIX but is not documented and it doesn't seem to work the same was as it does on other systems.  If you pass ac_cv_func_cfmakeraw=no to the configure script it will avoid using it and the behavior will be the same as with sudo 1.8.31p1.

Comment 4 altmark 2020-05-12 09:10:49 MDT

Ok, thank you! I'll give it a try and let you know.

Comment 5 altmark 2020-05-12 09:26:14 MDT

That fixed it. Thanks a lot for the quick help, Todd!

Comment 6 Todd C. Miller 2020-05-12 09:33:10 MDT

I've also rebuilt my AIX packages with that fix.

Comment 7 altmark 2020-05-12 09:40:14 MDT

Yep, they work for me, too. Thank you!

Comment 8 Todd C. Miller 2020-05-12 09:48:26 MDT

In case you are interested, the problem is that cfmakeraw() on AIX doesn't set VMIN to 1 or VTIME to 0 in c_cc in struct termios.  It also doesn't clear the CSIZE and PARENB flags from c_cflag but that's not as much of a problem.

Comment 9 altmark 2020-05-12 09:55:50 MDT

Yeah, unfortunately some of the functions in AIX don't seem to have the exact same behavior as their Linux counterparts of same name. Glad you knew right where to look and provided a fix so quickly. Thanks again and feel free to close this bug report.

Comment 10 Todd C. Miller 2020-06-19 06:00:35 MDT

Fixed in sudo 1.9.1