Re: [Qemu-devel] [PATCH] vmsvga: correct bitmap and pixmap size checks

[P J P]

+-- On Thu, 8 Sep 2016, P J P wrote --+
| From: Prasad J Pandit <address@hidden>
| 
| When processing svga command DEFINE_CURSOR in vmsvga_fifo_run,
| the computed BITMAP and PIXMAP size are checked against the
| 'cursor.mask[]' and 'cursor.image[]' array sizes in bytes.
| Correct these checks to avoid OOB memory access.
| 
| Reported-by: Qinghao Tang <address@hidden>
| Reported-by: Li Qiang <address@hidden>
| Signed-off-by: Prasad J Pandit <address@hidden>
| ---
|  hw/display/vmware_vga.c | 12 +++++++-----
|  1 file changed, 7 insertions(+), 5 deletions(-)
| 
| diff --git a/hw/display/vmware_vga.c b/hw/display/vmware_vga.c
| index e51a05e..6599cf0 100644
| --- a/hw/display/vmware_vga.c
| +++ b/hw/display/vmware_vga.c
| @@ -676,11 +676,13 @@ static void vmsvga_fifo_run(struct vmsvga_state_s *s)
|              cursor.bpp = vmsvga_fifo_read(s);
|  
|              args = SVGA_BITMAP_SIZE(x, y) + SVGA_PIXMAP_SIZE(x, y, 
cursor.bpp);
| -            if (cursor.width > 256 ||
| -                cursor.height > 256 ||
| -                cursor.bpp > 32 ||
| -                SVGA_BITMAP_SIZE(x, y) > sizeof cursor.mask ||
| -                SVGA_PIXMAP_SIZE(x, y, cursor.bpp) > sizeof cursor.image) {
| +            if (cursor.width > 256
| +                || cursor.height > 256
| +                || cursor.bpp > 32
| +                || SVGA_BITMAP_SIZE(x, y)
| +                    > sizeof(cursor.mask) / sizeof(cursor.mask[0])
| +                || SVGA_PIXMAP_SIZE(x, y, cursor.bpp)
| +                    > sizeof(cursor.image) / sizeof(cursor.image[0])) {
|                      goto badcmd;
|              }

Ping...!
--
Prasad J Pandit / Red Hat Product Security Team
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