Commit f9e3a2955d removing the MAXSCREEN limit left the screen
number too unlimited, and allowed any positive int for a screen number:
Xvfb :1 -screen 2147483647 1024x1024x8
Fatal server error:
Not enough memory for screen 2147483647
Found by Parfait 0.3.7:
Error: Integer overflow (CWE 190)
Integer parameter of memory allocation function realloc() may overflow due to multiplication with constant value 1112
at line 293 of hw/vfb/InitOutput.c in function 'ddxProcessArgument'.
Since the X11 connection setup only has a CARD8 for number of SCREENS,
limit to 255 screens, which is also low enough to avoid overflow on the
sizeof(*vfbScreens) * (screenNum + 1) calculation for realloc.
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Jamey Sharp <jamey@minilop.net>