--- src/sys/bus/cam/scsi/scsi_cd.c	2007/11/18 17:53:01	1.36
+++ src/sys/bus/cam/scsi/scsi_cd.c	2007/11/21 21:28:41	1.37
@@ -556,6 +556,8 @@ cdasync(void *callback_arg, u_int32_t co
 		cam_status status;
 
 		cgd = (struct ccb_getdev *)arg;
+		if (cgd == NULL)
+			break;
 
 		if (SID_TYPE(&cgd->inq_data) != T_CDROM
 		    && SID_TYPE(&cgd->inq_data) != T_WORM)