[Bug 3435] New: mux process command lines contains many 0x0
bugzilla-daemon at mindrot.org
bugzilla-daemon at mindrot.org
Mon May 16 05:01:13 AEST 2022
https://bugzilla.mindrot.org/show_bug.cgi?id=3435
Bug ID: 3435
Summary: mux process command lines contains many 0x0
Product: Portable OpenSSH
Version: v9.0p1
Hardware: Other
OS: Linux
Status: NEW
Severity: normal
Priority: P5
Component: ssh
Assignee: unassigned-bugs at mindrot.org
Reporter: calestyo at scientia.org
Hey.
I just noted something odd.
What I do is, construct (in a shell script) and execute a ssh command,
which some (constructed) options set and executes an (also constructed
and quite long) remote shell command.
When I do this on a connection for which I have control channel muxing
set up, the [mux] process gets very long cmdline.
The following is, when the (initiating) ssh command is still running:
$ ps ax | grep ssh
4712 ? Ss 0:00 /usr/bin/ssh-agent
cinnamon-session-cinnamon
543871 pts/18 S+ 0:00 ssh -o ClearAllForwardings=yes -o
ForwardAgent=no -o ForwardX11=no -o ForwardX11Trusted=no -o
GatewayPorts=no -o PermitLocalCommand=no -o PermitRemoteOpen=none -o
UpdateHostKeys=no -o BatchMode=yes foo.grid.lrz.de set -e
unset -v IFS export PATH='/usr/bin:/bin'
export LC_ALL='C' cd / sleep 400
p="/tmp/x509up_u$(id -u)"
t="$(mktemp)" { ?cat >"${t}" &&
?mv -f --no-target-directory "${t}" "${p}" }
|| { rm -f "${t}" && exit 10 || exit 20; } ?
{ ? ?m="$(stat --printf='%Y' "${p}")" && ?
?h="$(sha256sum "${p}")" && ? ?{ [ -n
"${p##*\'*}" ] && [ -n "${m##*\'*}" ] && [ -n "${h##*\'*}" ]; }
&& ? ? ? ?printf 'if [ "$(stat
--printf='\''%%Y '\'' '\''%s'\''; sha256sum '\''%s'\'')" = '\''%s
%s'\'' ]; then\n\trm -f '\''%s'\'';\nfi\n' "${p}" "${p}" "${m}" "${h}"
"${p}" | ? ?env -i PATH="${PATH}" LC_ALL="${LC_ALL}" ?
?at -M 'now + 3 minutes' 2>&1 ? } ||
{ rm -f "${p}" && exit 11 || exit 21; } ?
543876 ? Ss 0:00 ssh:
/home/calestyo/.ssh/mux/root at foo.grid.lrz.de:22 [mux]
543888 pts/19 S+ 0:00 grep --color=auto ssh
It probably cannot be seen well in bugzilla, but after the [mux]
process there are numerous empty lines (actually just the spaces after
the command).
Once the initiating ssh is Ctrl-C'ed:
$ ps ax | grep ssh
4712 ? Ss 0:00 /usr/bin/ssh-agent
cinnamon-session-cinnamon
543689 pts/20 S+ 0:00 vi bin/ssh_killall-mux
543876 ? Ss 0:00 ssh:
/home/calestyo/.ssh/mux/root at foo.grid.lrz.de:22 [mux]
544406 pts/19 S+ 0:00 grep --color=auto ssh
again, with loads of empty lines.
hd /proc/543876/cmdline
00000000 73 73 68 3a 20 2f 68 6f 6d 65 2f 63 61 6c 65 73 |ssh:
/home/cales|
00000010 74 79 6f 2f 2e 73 73 68 2f 6d 75 78 2f 72 6f 6f
|tyo/.ssh/mux/roo|
00000020 74 40 6c 63 67 2d 6c 72 7a 2d 61 64 6d 69 6e 2e
|t@*privacy* foo.|
00000030 67 72 69 64 2e 6c 72 7a 2e 64 65 3a 32 32 20 5b
|grid.lrz.de:22 [|
00000040 6d 75 78 5d 00 00 00 00 00 00 00 00 00 00 00 00
|mux]............|
00000050 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|................|
*
00000500 00 00 00 00 00 20 00 |..... .|
00000507
That may be quite annoying for anyone who e.g. uses pgrep to kill mux
processes and expects the name to end after the "]" ;-)
And another odd thing (please tell whether this is expected or not,
cause then I'd open a new ticket):
You've noticed the sleep 400 in my remote command (which was just there
fore debugging)?
Even when I Ctrl-C the (mux-initiating) ssh right after the start, the
[mux] process lingers around for those 400+ControlPersist seconds.
Well not exactly those it actually differs a few seconds... (which I
found also a bit add).
Shouldn't ControlPersist "start to count" when the last connection is
gone and shouldn't that happen with the Ctrl-C?
Thanks,
Chris.
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