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Bug 745675 - black screen on login after changing session
black screen on login after changing session
Status: RESOLVED FIXED
Product: gdm
Classification: Core
Component: general
unspecified
Other Linux
: Normal normal
: ---
Assigned To: GDM maintainers
GDM maintainers
Depends on:
Blocks:
 
 
Reported: 2015-03-05 12:55 UTC by Matthias Clasen
Modified: 2015-03-17 16:34 UTC
See Also:
GNOME target: 3.16
GNOME version: ---

Attachments
worker: abort if we can't fix up terminal mode (4.49 KB, patch)
2015-03-17 16:32 UTC, Ray Strode [halfline] 		none Details | Review

Description Matthias Clasen 2015-03-05 12:55:54 UTC 
I experience the following:

On the login screen, change session to classic mode, and proceed to login
End up with a black screen from which only a reboot is possible
After reboot, log in again without changing session type
Get to classic mode just fine

Same experience when switching back to gnome
Comment 1 Matthias Clasen 2015-03-05 14:01:40 UTC 
not entirely reproducible here, but local debugging turned up some selinux problems related to CAP_SYS_TTY
Comment 2 Matthias Clasen 2015-03-05 14:04:18 UTC 
whats concerning is that I end up seeing my password in cleartext on the vt after the login screen finally crashes. We should probably treat that as a blocker.
Comment 3 Ray Strode [halfline] 2015-03-17 16:32:48 UTC 
Created attachment 299612 [details] [review]
worker: abort if we can't fix up terminal mode

An overzealous SELinux policy can lead to required tty ioctls
failing.  Various bits of GDM, the X server and wayland expect these
ioctls to succeed, so bail early if they fail.
Comment 4 Ray Strode [halfline] 2015-03-17 16:34:05 UTC 
This is pretty much NOTGNOME, but I pushed this patch:

Attachment 299612 [details] pushed as 31e0b50 - worker: abort if we can't fix up terminal mode

to make sure GDM fails up front in this situation rather than letting
the display servers try to bustle on and get confused.