[PATCH 1/2] drm/vmwgfx: Validate the box size for the snooped cursor

[Zack Rusin]

From: Zack Rusin <zackr at vmware.com>

Invalid userspace dma surface copies could potentially overflow
the memcpy from the surface to the snooped image leading to crashes.
To fix it the dimensions of the copybox have to be validated
against the expected size of the snooped cursor.

Signed-off-by: Zack Rusin <zackr at vmware.com>
Fixes: 2ac863719e51 ("vmwgfx: Snoop DMA transfers with non-covering sizes")
Cc: <stable at vger.kernel.org> # v3.2+
Reviewed-by: Michael Banack <banackm at vmware.com>
Reviewed-by: Martin Krastev <krastevm at vmware.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
index 0342efdf9063..d434b6ae1092 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
@@ -393,7 +393,8 @@ void vmw_kms_cursor_snoop(struct vmw_surface *srf,
 	if (cmd->dma.guest.ptr.offset % PAGE_SIZE ||
 	    box->x != 0    || box->y != 0    || box->z != 0    ||
 	    box->srcx != 0 || box->srcy != 0 || box->srcz != 0 ||
-	    box->d != 1    || box_count != 1) {
+	    box->d != 1    || box_count != 1 ||
+	    box->w > 64 || box->h > 64) {
 		/* TODO handle none page aligned offsets */
 		/* TODO handle more dst & src != 0 */
 		/* TODO handle more then one copy */
-- 
2.34.1