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vga: add vga_scanline_invalidated helper 

Add vga_scanline_invalidated helper to check whenever a scanline was
invalidated.  Add a sanity check to fix OOB read access for display
heights larger than 2048.

Only cirrus uses this, for hardware cursor rendering, so having this
work properly for the first 2048 scanlines only shouldn't be a problem
as the cirrus can't handle large resolutions anyway.  Also changing the
invalidated_y_table size would break live migration.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20170421091632.30900-4-kraxel@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Gerd Hoffmann 2017-04-21 11:16:26 +02:00
parent 8deaf12ca1
commit f3289f6f0f
1 changed files with 11 additions and 3 deletions
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14
hw/display/vga.c
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@ -1434,6 +1434,14 @@ void vga_invalidate_scanlines(VGACommonState *s, int y1, int y2)
}
}
static bool vga_scanline_invalidated(VGACommonState *s, int y)
{
if (y >= VGA_MAX_HEIGHT) {
return false;
}
return s->invalidated_y_table[y >> 5] & (1 << (y & 0x1f));
}
void vga_sync_dirty_bitmap(VGACommonState *s)
{
memory_region_sync_dirty_bitmap(&s->vram);
@ -1638,8 +1646,8 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
page1 = addr + bwidth - 1;
update |= memory_region_get_dirty(&s->vram, page0, page1 - page0,
DIRTY_MEMORY_VGA);
/* explicit invalidation for the hardware cursor */
update |= (s->invalidated_y_table[y >> 5] >> (y & 0x1f)) & 1;
/* explicit invalidation for the hardware cursor (cirrus only) */
update |= vga_scanline_invalidated(s, y);
if (update) {
if (y_start < 0)
y_start = y;
@ -1686,7 +1694,7 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
page_max - page_min,
DIRTY_MEMORY_VGA);
}
memset(s->invalidated_y_table, 0, ((height + 31) >> 5) * 4);
memset(s->invalidated_y_table, 0, sizeof(s->invalidated_y_table));
}
static void vga_draw_blank(VGACommonState *s, int full_update)