Got errors when using sudo with ps

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
25/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
python
Domain
cli, devtools

Research direction

Start at watchers.Responder.submit and follow runner.Runner.handle_output, _handle_output, respond, and write_proc_stdin. Reproduce the sudo ps axww command on Debian and inspect the response triggered by the process-list output. Done means the output no longer causes a password write after the Paramiko channel closes or an OSError: Socket is closed ThreadException.

Written by the indexing model from the issue text.

Description

Hi,

This is not exactly an issue, more of a warning for people having this kind of issues. It is both related to the invoke and the paramiko library

I am using fabric (which is based on paramiko and invoke) in order to retrieve a list of running processus on a Debian server with ps axww -o pid=,ppid=,etimes=,command=. At that time, I used the sudo function to run it.

From time to time, I got a ThreadException, and it came out that it was coming from the invoke library: when doing the ps command, I got the following output:

3432669       1       0 /lib/systemd/systemd --user
3432670 3432669       0 (sd-pam)
3432716       2       0 [kworker/9:1]
3432730 3432625       0 sshd: xxx@notty
3432731 3432730       0 sudo -S -p [sudo] password:  ps axww -o pid=,ppid=,etimes=,command=
3432732 3432731       0 ps axww -o pid=,ppid=,etimes=,command=

As the -p [sudo] password: option appears in the command output, the watchers.Responder.submit function returns matches, and triggers the runner.Runner.handle_output -> _handle_output -> respond -> write_proc_stdin function, thinking it should send the password.

As the paramiko channel get closed once the command output is printed, the write_proc_stdin sometimes tries to write the password after the channel closure, which triggers a ThreadException OSError: Socket is closed

(Sorry if I am not using the correct terminology, I am not a developer)

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