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

[Wisefox]

Hi Michael

Please paste the result of cat /proc/`pidof sshd | awk '{print
$1}'`/status | grep SigBlk.  If the problem is not caused by sigmask.
The workaround can't work. :)

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sshd zombie processes and strange behavior after karmic upgrade
https://bugs.launchpad.net/bugs/407428
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[Bug 407428] Re: sshd zombie processes and strange behavior after karmic upgrade

[Wisefox]

Hi Brett. 
I forgot to mention that:

You need to logout from current console. Then login your machine.

Sorry for that.

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sshd zombie processes and strange behavior after karmic upgrade
https://bugs.launchpad.net/bugs/407428
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[Bug 407428] Re: sshd zombie processes and strange behavior after karmic upgrade

[Wisefox]

Well. Provide a piece of code as a workaround. compile the following C code:

#include signal.h

int main( int argc, char ** argv )
{

sigset_t oldset, newset;
sigfillset( newset );
sigprocmask( SIG_UNBLOCK, newset, oldset );
int pid = fork();
if ( pid == 0 )
{
execvp( argv[1], (argv[1]) );
perror(\n);
}
else
{
printf(father return;\n);
}
}
=
gcc -o sigwapper thisfile.c
=
Use the program to fix the problem as workaround. need root privilege :
=
$ ./sigwapper /etc/init.d/ssh restart
=
Check if the C + c is back or not.

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

[Wisefox]

Seems latest update fix the problem. But now, I get ext4 and shutdown
problem.

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sshd zombie processes and strange behavior after karmic upgrade
https://bugs.launchpad.net/bugs/407428
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[Bug 407428] Re: sshd zombie processes and strange behavior after karmic upgrade

[Wisefox]

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: 
SigBlk: fffe7ffb9eff  # should be all zero
SigIgn: 
SigCgt: 000180006000

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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