@@ -1,4 +1,4 @@
-/*	$NetBSD: drm_ioctl.c,v 1.24 2022/10/15 15:19:28 riastradh Exp $	*/
+/*	$NetBSD: drm_ioctl.c,v 1.25 2024/04/21 03:02:51 riastradh Exp $	*/
 
 /*
  * Created: Fri Jan  8 09:01:26 1999 by faith@valinux.com
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: drm_ioctl.c,v 1.24 2022/10/15 15:19:28 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: drm_ioctl.c,v 1.25 2024/04/21 03:02:51 riastradh Exp $");
 
 #include <linux/export.h>
 #include <linux/nospec.h>
@@ -129,19 +129,35 @@
 		  struct drm_file *file_priv)
 {
 	struct drm_unique *u = data;
-	struct drm_master *master = file_priv->master;
+	struct drm_master *master;
+	int ret;
 
-	mutex_lock(&master->dev->master_mutex);
-	if (u->unique_len >= master->unique_len) {
-		if (copy_to_user(u->unique, master->unique, master->unique_len)) {
-			mutex_unlock(&master->dev->master_mutex);
-			return -EFAULT;
-		}
+	mutex_lock(&dev->master_mutex);
+	master = dev->master;
+	if (master == NULL) {
+		ret = -ENXIO;
+		goto out;
 	}
+
+	/*
+	 * Copy out only if the user allocated enough space.  Either
+	 * way, on success, report the actual size -- so the user can
+	 * allocate enough space if they didn't before, or so they know
+	 * exactly how much we copied out.
+	 */
+	if (u->unique_len < master->unique_len) {
+		ret = 0;
+	} else {
+		ret = copy_to_user(u->unique, master->unique,
+		    master->unique_len);
+		if (ret)
+			goto out;
+	}
 	u->unique_len = master->unique_len;
-	mutex_unlock(&master->dev->master_mutex);
 
-	return 0;
+out:	mutex_unlock(&dev->master_mutex);
+
+	return ret;
 }
 
 static void
@@ -597,7 +613,7 @@
 /* Ioctl table */
 static const struct drm_ioctl_desc drm_ioctls[] = {
 	DRM_IOCTL_DEF(DRM_IOCTL_VERSION, drm_version, DRM_RENDER_ALLOW),
-	DRM_IOCTL_DEF(DRM_IOCTL_GET_UNIQUE, drm_getunique, 0),
+	DRM_IOCTL_DEF(DRM_IOCTL_GET_UNIQUE, drm_getunique, DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF(DRM_IOCTL_GET_MAGIC, drm_getmagic, 0),
 	DRM_IOCTL_DEF(DRM_IOCTL_IRQ_BUSID, drm_irq_by_busid, DRM_MASTER|DRM_ROOT_ONLY),