Public bug reported:
When using "/bin/sh" (dash) as a shell for ssh, or just starting /bin/sh
in a terminal, when the shell receives a wall message (from another user
or root), it just quits.
How to reproduce:
- start a terminal (xterm, gnome-terminal, etc), usually starts with bash
- from bash run 'sh' command to open a dash shell
- start another terminal, and run: echo "foo" | wall
- the broadcast message appears on both terminals
- in the first terminal you are thrown back to bash, because dash exits
I've tried this on Ubuntu 14.04, 16.04, 18.04 (64bits) latest updates
and it's happening on all of them. I've also tried with latest dash from
git, compiled on Ubuntu 16.04, same problem, that's why I don't think
it's dash's problem.
Also tried on CentOS 7, there is no problem there.
The problem appears this morning (6 February) after updating to latest
version of 16.04, 18.04. I also have a box with 16.04 but not the latest
updates, and on that box the problem does not happen.
If one uses dash as a login shell, and enters on a remote box with SSH
for example, the connection can be terminated by another user simply
wall'ing a broadcast message (or a system daemon like NUT). This could
be taken as a potential security issue.
** Affects: ubuntu
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1814905
Title:
dash exits when receiving wall message
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