[Bug 407428] Re: sshd zombie processes and strange behavior after karmic upgrade

Wisefox shangxiaole at gmail.com
Tue Aug 25 07:44:47 BST 2009


Don't know the developer already get the root cause or not. I can
provide some clue deeper into this issue.

When Karmic starts the ssh and other several services(udevd,dhcp etc.), it uses a wrong Sigmask set for the program:
Check the Sigblk for sshd:
$ cat /proc/`pidof sshd| awk '{print $1}'`/status | grep Sig
SigQ:	4/16297
SigPnd:	0000000000000000
SigBlk:	fffffffe7ffb9eff                          # should be all zero
SigIgn:	0000000000000000
SigCgt:	0000000180006000

All child forked by sshd will succeed the same SigBlk from sshd. And the Ctrl + C token uses the SIGINT(2) to interrupt the program. But it's blocked by the program. That's the cause of sshd zombie and Ctrl + C problem.
I provide two method to get sshd back to normal.
1). On that machine(physical), use the /etc/init.d/ssh stop/start to restart ssh to make it use the right mask.
2). Write a little wrapper program to restart the ssh.

-- 
sshd zombie processes and strange behavior after karmic upgrade
https://bugs.launchpad.net/bugs/407428
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