[X2Go-Dev] Bug#759: x2goclient 4.0.5.0 (and 4.0.5.1 preview) frequent ssh commands don't free resources
Mat Martineau
mathew.j.martineau at linux.intel.com
Wed Feb 17 18:00:44 CET 2016
I've run in to this problem as well, with these x2go versions:
Client (Mac)
* x2goclient 4.0.5.0 (OS X 10.9+ build) or 4.0.5.1 preview (December 2015
build)
* OS X 10.11.3
* XQuartz 2.7.8
Server (Linux)
* x2goagent: 3.5.0.32
* x2goserver: 4.0.1.19
* x2goserver-extensions: 4.0.1.19
* Fedora 23 (with updates as of 2016-02-17)
Steps to reproduce:
1. Run 'x2goclient --debug' and open a session
2. Observe frequent xmodmap commands while session is active
3. Quit session to see a large number of SshProcess objects freed
This came to my attention because the default SELinux/audit settings on
Fedora 23 log five events for each xmodmap ssh command executed on the
server by the client. That's 1800 events per hour when an x2go session is
active.
Judging from ONMainWindow::slotSetModMap() in onmainwindow.cpp, it looks
like the intent is to only run the xmodmap command if kbMap is empty
(maybe there's an expected way for kbMap to get cleared so it has to be
periodically checked?). However, slotSetModMap() runs every 10 seconds and
executes a command every time. It's not clear to me how kbMap becomes
empty.
Furthermore, the SshProcess objects are not cleaned up until the session
is exited. The 'processes' QList in SshMasterConnection grows without
bound.
Logs from x2goclient --debug:
"""
x2go-DEBUG-../src/sshprocess.cpp:199> Executing remote command via
SshProcess object 6: "export DISPLAY=":50"; echo "keycode 8 = a A aring
Aring
<snip>"
x2go-DEBUG-../src/sshprocess.cpp:204> Running
masterCon->addChannelConnection(this,
'"d93c9f1a-2d4d-42fb-92a9-5373621768f6"', '"bash -c 'echo
"X2GODATABEGIN:d93c9f1a-2d4d-42fb-92a9-5373621768f6"; export
PATH="/usr/local/bin:/usr/bin:/bin"; export DISPLAY=":50"; echo "keycode
8 = a A aring Aring
keycode 9 = s S ssharp Iacut"');
x2go-DEBUG-../src/sshmasterconnection.cpp:1284> Locking SSH channel
connection MUTEX.
x2go-DEBUG-../src/sshmasterconnection.cpp:1286> Passing new channel
conenction object to channelConnections.
x2go-DEBUG-../src/sshmasterconnection.cpp:1288> Unlocking SSH channel
connection MUTEX.
x2go-DEBUG-../src/sshmasterconnection.cpp:1476> Creating new channel.
x2go-DEBUG-../src/sshmasterconnection.cpp:1480> New channel:0x7fcb9a7af450
x2go-DEBUG-../src/sshmasterconnection.cpp:1511> Executing remote: "bash -c
'echo "X2GODATABEGIN:d93c9f1a-2d4d-42fb-92a9-5373621768f6"; export
PATH="/usr/local/bin:/usr/bin:/bin"; export DISPLAY=":50"; echo "keycode
8 = a A aring Aring
<snip>"
x2go-DEBUG-../src/sshmasterconnection.cpp:1534> New exec channel created.
x2go-DEBUG-../src/sshmasterconnection.cpp:1638> EOF on channel
0x7fcb9a7af450; SshProcess object: 6
x2go-DEBUG-../src/sshmasterconnection.cpp:1706> EOF sent.
x2go-DEBUG-../src/sshmasterconnection.cpp:1710> Channel closed.
x2go-DEBUG-../src/sshprocess.cpp:517> SSH finished: raw output (stdout):
"X2GODATABEGIN:d93c9f1a-2d4d-42fb-92a9-5373621768f6
X2GODATAEND:d93c9f1a-2d4d-42fb-92a9-5373621768f6
"
x2go-DEBUG-../src/sshprocess.cpp:528> SSH finished: true - "" (6).
<repeat every 10 seconds>
"""
And the log of SshProcess cleanup when the session is disconnected after a
little over one minute:
"""
x2go-DEBUG-../src/sshmasterconnection.cpp:715> SshMasterConnection,
instance SshMasterConnection(0x7fcb9cc51a90) thread finished.
x2go-DEBUG-../src/sshprocess.cpp:52> SshProcess destructor called.
x2go-DEBUG-../src/sshprocess.cpp:52> SshProcess destructor called.
x2go-DEBUG-../src/sshprocess.cpp:52> SshProcess destructor called.
x2go-DEBUG-../src/sshprocess.cpp:52> SshProcess destructor called.
x2go-DEBUG-../src/sshprocess.cpp:52> SshProcess destructor called.
x2go-DEBUG-../src/sshprocess.cpp:52> SshProcess destructor called.
x2go-DEBUG-../src/sshprocess.cpp:52> SshProcess destructor called.
x2go-DEBUG-../src/sshprocess.cpp:52> SshProcess destructor called.
x2go-DEBUG-../src/sshprocess.cpp:52> SshProcess destructor called.
x2go-DEBUG-../src/sshmasterconnection.cpp:722> SshMasterConnection,
instance SshMasterConnection(0x7fcb9cc51a90) finished destructor.
"""
--
Mat Martineau
Intel OTC
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