[PATCH 03/12] macfb: fix overflow of color_palette array

[Mark Cave-Ayland]

The palette_current index counter has a maximum size of 256 * 3 to cover a full
color palette of 256 RGB entries. Linux assumes that the palette_current index
wraps back around to zero after writing 256 RGB entries so ensure that
palette_current is reset at this point to prevent data corruption within
MacfbState.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
---
 hw/display/macfb.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/hw/display/macfb.c b/hw/display/macfb.c
index 815870f2fe..f4e789d0d7 100644
--- a/hw/display/macfb.c
+++ b/hw/display/macfb.c
@@ -307,6 +307,9 @@ static void macfb_ctrl_write(void *opaque,
         if (s->palette_current % 3) {
             macfb_invalidate_display(s);
         }
+        if (s->palette_current >= sizeof(s->color_palette)) {
+            s->palette_current = 0;
+        }
         break;
     }
 }
-- 
2.20.1