[PATCH 4.14 067/118] drm/vmwgfx: Potential off by one in vmw_view_add()

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

commit 0d9cac0ca0429830c40fe1a4e50e60f6221fd7b6 upstream.

The vmw_view_cmd_to_type() function returns vmw_view_max (3) on error.
It's one element beyond the end of the vmw_view_cotables[] table.

My read on this is that it's possible to hit this failure.  header->id
comes from vmw_cmd_check() and it's a user controlled number between
1040 and 1225 so we can hit that error.  But I don't have the hardware
to test this code.

Fixes: d80efd5cb3de ("drm/vmwgfx: Initial DX support")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Reviewed-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -2731,6 +2731,8 @@ static int vmw_cmd_dx_view_define(struct
 	}
 
 	view_type = vmw_view_cmd_to_type(header->id);
+	if (view_type == vmw_view_max)
+		return -EINVAL;
 	cmd = container_of(header, typeof(*cmd), header);
 	ret = vmw_cmd_res_check(dev_priv, sw_context, vmw_res_surface,
 				user_surface_converter,