Control flow is:
PanoramiXMaybeAddDepth() allocates an array size 240 (pDepth->numVisuals)
PanoramiXMaybeAddVisual() finds up to 270 matches (pScreen->numVisuals)
and writes those into the previously allocated array.
This caused invalid reads/writes followed by eventually a double-free abort.
Reproduced with xorg-integration-tests server test
XineramaTest.ScreenCrossing/* (and a bunch of others).
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Keith Packard <keithp@keithp.com>
93cafb0828