Bug 28825 – screen will not unlock with kernel 2.6

• Status: RESOLVED FIXED
• Product: Gentoo Linux

[Description Jonathan Brown 2003-09-15 14:20:29 UTC]

When runnning screen under kernel 2.6.0-test5 it will not accept my password and
will not unlock. Doing the same under 2.4.22 is fine.

Reproducible: Always
Steps to Reproduce:
1.boot 2.6 kernel
2.run screen
3.ctrl-a x -- to lock
4.type in password

Actual Results:  
screen does not unlock

Expected Results:  
unlocked

This might be the same problem that xscreensaver had -- something to do with
signal handling I think.

[Comment 1 Tim Yamin (RETIRED) 2003-09-20 05:43:44 UTC]

Try upgrading xscreensaver to the latest version and remerge pam...

[Comment 2 Jonathan Brown 2003-09-20 06:01:25 UTC]

If you had actually read my bug you would know that the problem is not with xscreensaver. What I saying is that a bug in app-misc/screen is probably caused by the same problem that afflicted xsceensaver many months ago.

[Comment 3 Tim Yamin (RETIRED) 2003-09-20 06:56:35 UTC]

Can you please attach an strace of the process please, then? [emerge strace; strace -p <process-id>]

[Comment 4 Jonathan Brown 2003-09-20 08:00:11 UTC]

Created attachment 18034 [details]
strace of screen exhibiting unable to unlock problem

[Comment 5 Jonathan Brown 2003-09-20 08:01:12 UTC]

Created attachment 18035 [details]
strace of screen exhibiting unable to unlock problem

[Comment 6 Jonathan Brown 2003-09-20 08:30:03 UTC]

This bugzilla spurts out an error when I make an attachment. The attachment is included in the bug, but no emails are sent out. So this comment should send out the emails.

[Comment 7 Martin Holzer (RETIRED) 2003-10-13 12:35:36 UTC]

4.0.1 is in cvs

does this fix ?

[Comment 8 Jonathan Brown 2003-10-13 18:09:02 UTC]

no - still doesn't work

[Comment 9 Tim Yamin (RETIRED) 2003-11-18 08:42:04 UTC]

In the strace:-
---------------

access("/var/run/utmpx", F_OK)          = -1 ENOENT (No such file or directory)
open("/var/run/utmp", O_RDWR)           = -1 EACCES (Permission denied)

[Comment 10 Jonathan Brown 2003-11-18 13:16:04 UTC]

I think strace does something to screw up the setuid bit.

Also - running "screen" will start screen, but running "strace screen 2> strace-screen" throws up this error:

Directory '/var/run/screen' must have mode 777.

I think I did chmod 777 /var/run/screen on my old install to get strace to work.

Running screen as root will be able to unlock under 2.6, but not when run as a normal user with or without strace.

[Comment 11 Tim Yamin (RETIRED) 2003-11-19 08:20:10 UTC]

Use "strace -o <outputfile> <command>" to dump strace output to a file.

[Comment 12 Tobias Klausmann (RETIRED) 2003-12-04 02:16:31 UTC]

Here's my strace, I'm having the very same problem.

Done with strace -o strace.log screen, the immediately using c-a-x and entering the password (obfuscated in the trace file) once.

[Comment 13 Tobias Klausmann (RETIRED) 2003-12-04 02:21:09 UTC]

Created attachment 21680 [details]
strace of failing screen unlock attempt

K2.6.0-t11, screen 4.00.01

[Comment 14 Luke Macken (RETIRED) 2004-01-15 20:11:42 UTC]

I had this same problem with screen ctrl-a+x and also with xlock.

To fix this you need to upgrade sys-libs/pam to 0.77.

[Comment 15 Tim Yamin (RETIRED) 2004-01-20 08:55:17 UTC]

This seems to fixed by a PAM upgrade - please see comment #14...