Light Display Manager

lightdm set SIGPIPE disposition to SIG_IGN even for children

Series 1.10
Bug #1579867

Bug #1579867 reported by Yves-Alexis Perez on 2016-05-09

This bug affects 1 person

	Status	Importance	Assigned to	Milestone
Light Display Manager	Fix Committed	Medium	Unassigned	Light Display Manager 1.21.0
1.10	Fix Committed	Medium	Unassigned	Light Display Manager 1.10.7
1.18	Fix Committed	Medium	Unassigned	Light Display Manager 1.18.4
1.2	Won't Fix	Medium	Unassigned
1.20	Fix Committed	Medium	Unassigned	Light Display Manager 1.20.1
lightdm (Debian)	Fix Released	Unknown	debbugs #823460
lightdm (Ubuntu)	Triaged	Medium	Unassigned
Precise	Won't Fix	Medium	Unassigned
Trusty	Triaged	Medium	Unassigned
Xenial	Triaged	Medium	Unassigned
Yakkety	Triaged	Medium	Unassigned

Bug Description

Hi,

a Debian user reported that his session was running with SIGPIPE set to SIG_IGN, and tracked the issue to lightdm.

The whole investigation is in the downstream bug, but in summary the glib gio functions set the disposition, and nothing reverts it. Using g_spawn_*() function should do it, but they're apparently not used in lightdm.

The reporter also provided a minimal patch, which is attached.

Tags:

Related branches

lp://staging/lightdm

lp://staging/lightdm/1.20

lp://staging/lightdm/1.18

lp://staging/lightdm/1.10

Revision history for this message

Yves-Alexis Perez (corsac) wrote on 2016-05-09:

reset SIGPIPE to SIG_DFL after forking Edit (870 bytes, text/plain)

Revision history for this message

Yves-Alexis Perez (corsac) wrote on 2016-10-17:

Hi,

is there some news on this? Can you at least comment on the patch even without integrating it, so I can move forward and include it (or not) in the Debian package?

Revision history for this message

Robert Ancell (robert-ancell) wrote on 2016-10-19:

Hi,

Sorry for the delay. I'm not sure where the downstream bug is but looking through the GLib source code I can confirm the GSocket code does set SIGPIPE to SIG_IGN. So the attached patch will correctly revert it to the default for the child processes. As far as I can tell this is the right thing to do.

Revision history for this message

Robert Ancell (robert-ancell) wrote on 2016-10-19:

http://stackoverflow.com/questions/8369506/why-does-sigpipe-exist has a good description of why this is a stupid signal you don't want to handle...

Revision history for this message

Robert Ancell (robert-ancell) wrote on 2016-10-19:

Commited this patch with the following changes:
- I explicitly disable SIGPIPE when LightDM starts (because I don't want it to occur anywhere).
- I re-enable it just before I exec() the children so it can't affect any of the LightDM code.

Changed in lightdm:
milestone:	none → 1.21.0
status:	New → Fix Committed
importance:	Undecided → Medium

Bug Watch Updater (bug-watch-updater) on 2016-10-19

Changed in lightdm (Debian):
status:	Unknown → Confirmed

Robert Ancell (robert-ancell) on 2016-10-20

Changed in lightdm (Ubuntu):
importance:	Undecided → Medium
Changed in lightdm (Ubuntu Trusty):
importance:	Undecided → Medium
Changed in lightdm (Ubuntu Yakkety):
importance:	Undecided → Medium
Changed in lightdm (Ubuntu Xenial):
importance:	Undecided → Medium
Changed in lightdm (Ubuntu Yakkety):
status:	New → Triaged
Changed in lightdm (Ubuntu Xenial):
status:	New → Triaged
Changed in lightdm (Ubuntu Trusty):
status:	New → Triaged
Changed in lightdm (Ubuntu):
status:	New → Triaged

Robert Ancell (robert-ancell) on 2016-10-20

Changed in lightdm (Ubuntu Precise):
importance:	Undecided → Medium
status:	New → Won't Fix

Revision history for this message

Ubuntu Foundations Team Bug Bot (crichton) wrote on 2016-10-20:

The attachment "reset SIGPIPE to SIG_DFL after forking" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issues please contact him.]

tags:

added: patch

Bug Watch Updater (bug-watch-updater) on 2016-10-20