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

[Mark Cave-Ayland]

On 04/10/2021 09:53, Laurent Vivier wrote:

Le 02/10/2021 à 12:59, Mark Cave-Ayland a écrit :

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-ayl...@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;
      }
  }

What about "s->palette_current = (s->palette_current + 1) % 
sizeof(s->color_palette)"?

Thanks,
Laurent

Sure, I can update that for v2.


ATB,

Mark.