dom.constant@free.fr authored Feb 06, 2018 and Chris Wilson committed Mar 02, 2018

For my HTPC setup, I'm using the option "CustomEDID".
With this option, output attaching and destroying events leads to
crashes.

The following sequence leads to a crash:
- In xorg.conf: Option "CustomEDID" "HDMI2:/etc/my_edid.bin"
- Starting Xorg
- Connect HDMI2
- Disconnect HDMI2
- Reconnect HDMI2
  -> Crash

The crash happens in xf86OutputSetEDID
(xorg/xserver/hw/xfree86/modes/xf86Crtc.c)
at "free(output->MonInfo)". MonInfo is assigned with
sna_output->fake_edid_mon
which is allocated by intel driver in sna_output_load_fake_edid
(src/sna/sna_display.c).

Sequence details:
- Starting Xorg
   -> fake_edid_mon is initialized

- Connect HDMI2
   -> xf86OutputSetEDID is called:
       - MonInfo is NULL
       - MonInfo is assigned with fake_edid_mon pointer
       - MonInfo is read by Xorg

- Disconnect HDMI2

- Reconnect HDMI2
   -> xf86OutputSetEDID is called:
       - MonInfo is freed thus also fake_edid_mon
       - MonInfo is assigned with fake_edid_mon
       - MonInfo is read but it was freed -> CRASH

The fix consists of a new instance of xf86MonPtr for each calls of
xf86OutputSetEDID.
is initialized with fake_edid_raw which render
fake_edid_mon useless.
With this proposal, the behaviour of an EDID override is similar to
a "real" EDID.

Signed-off-by: Dominique Constant <dom.constant@free.fr>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>