--- linux/drivers/char/drm/i810_dma.c	Mon Apr 12 10:54:26 2004
+++ linux/drivers/char/drm/i810_dma.c	Fri Apr 16 11:46:32 2004
@@ -1275,6 +1275,9 @@
 		return -EINVAL;
 	}
 
+	if (mc.idx >= dma->buf_count || mc.idx < 0)
+		return -EINVAL;
+
 	i810_dma_dispatch_mc(dev, dma->buflist[mc.idx], mc.used,
 		mc.last_render );