killing su does not kill subprocess (SIGTERM not propagated)

[Radu Duta]

Problem first appeared in login_4.1.5.1-1ubuntu9.4 and version login_4.1.5.1-1ubuntu9.2 was not affected.

Example where the subprocess 115576 has not been terminated:
root@ubuntu:~/sudebug/src/shadow-4.1.5.1/src# pkill sleep; ./su test -c 'sleep 9999'&
[1] 115575
root@ubuntu:~/sudebug/src/shadow-4.1.5.1/src# kill $!
root@ubuntu:~/sudebug/src/shadow-4.1.5.1/src# ...waiting for child to terminate.
pgrep sleep
115576
[1]+ Exit 255 ./su test -c 'sleep 9999'
root@ubuntu:~/sudebug/src/shadow-4.1.5.1/src# pgrep sleep
115576

Expected behavior:
root@ubuntu:~/sudebug/src/shadow-4.1.5.1/src# pkill sleep; ./su test -c 'sleep 9999' &
[1] 115503
root@ubuntu:~/sudebug/src/shadow-4.1.5.1/src# kill $!
root@ubuntu:~/sudebug/src/shadow-4.1.5.1/src#
Session terminated, terminating shell... ...terminated.
 ...terminated.

[1]+ Exit 143 ./su test -c 'sleep 9999'
root@ubuntu:~/sudebug/src/shadow-4.1.5.1/src# pgrep sleep

[Serge Hallyn (serge-hallyn)]

Thanks for filing, Radu.

The commit which fixed it is in this PR:

https://github.com/shadow-maint/shadow/pull/72

(wget https://github.com/shadow-maint/shadow/pull/72.patch)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Seth Arnold (seth-arnold)]

Radu, thanks for the top-notch bug report.

Serge, Tobias, thanks for the rapid fix.

https://www.ubuntu.com/usn/usn-3276-2/