diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 93a112d45c1ad11b74e7b9fece1e84d236c01b5d..7a87e0878f3008f5db63d850c9e9603fdbf79de1 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -438,6 +438,8 @@ long drm_ioctl(struct file *filp,
 					goto err_i1;
 				}
 			}
+			if (asize > usize)
+				memset(kdata + usize, 0, asize - usize);
 		}
 
 		if (cmd & IOC_IN) {