EDID data leaks to other outputs.
Submitted by lpe..@..ga.edu
Assigned to Keith Packard
Created attachment 139631 xrandr output on affected system
On i5 system using Intel integrated graphics. Gigabyte GA-H97N motherboard.
Monitor is connected to one VGA input via a TrendNet TK-207K KVM.
First output of xrandr in attached file is with the KVM set to view the affected unit. Second output of xrandr in attached file is with the KVM set to its other input.
Note that the KVM is the only display device attached to the affected system.
Note that when the KVM is not viewing the affected unit, EDID data seems to be "leaking" from VGA-1 where the KVM is attached over to HDMI-3 which has nothing attached. I suspect this bug is lower in the stack than xrandr, but I'm not certain how to test that, and I don't see any promising entries in the component list so I'm starting here.
Tested with xorg server versions 1.19.5 and 1.20.0
This smells to me like it might be a potential security issue (albeit a minor one considering the necessity of physical access) since EDID data overflowing from one input to another seems like some kind of buffer overflow somewhere.
If you are unable to reproduce this issue, I may be able to arrange for remote access to the hardware in question.
If you can provide me with diagnostic steps to extract further information I would be happy to oblige. Xorg is rather out of my normal areas of expertise.
Attachment 139631, "xrandr output on affected system":