commit 83adebf

Use memset to initialize memory on screen resize.

Previously the system used realloc to increase the size
of the fg and bg pixel arrays and just used the memory
as-is. However, this can lead to problems because pixel
values are expected to be 0-3 and are used to index into
the 16 element palette array.

On some platforms memory returned by realloc is not
initialized to zero, which can lead to large fg and bg
pixel values which lead to an out of bounds palette
access (i.e. a segmentation fault).

Using memset after realloc ensures that pixel data starts
at a valid value (zero). This means that as long as no
other code sets fg or bg pixels to invalid values, it is
safe to directly index into the palette.

 1@@ -1,4 +1,5 @@
 2 #include <stdlib.h>
 3+#include <string.h>
 4 
 5 #include "../uxn.h"
 6 #include "screen.h"
 7@@ -72,6 +73,8 @@ screen_apply(int width, int height)
 8 	clamp(height, 8, 0x800);
 9 	length = MAR2(width) * MAR2(height);
10 	uxn_screen.bg = realloc(uxn_screen.bg, length), uxn_screen.fg = realloc(uxn_screen.fg, length);
11+	memset(uxn_screen.bg, 0, length);
12+	memset(uxn_screen.fg, 0, length);
13 	uxn_screen.width = width, uxn_screen.height = height;
14 	screen_change(0, 0, width, height);
15 	emu_resize();