Patch "drm: Check for lessee in DROP_MASTER ioctl" has been added to the 4.15-stable tree

Patch "drm: Check for lessee in DROP_MASTER ioctl" has been added to the 4.15-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    drm: Check for lessee in DROP_MASTER ioctl

to the 4.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-check-for-lessee-in-drop_master-ioctl.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 761e05a702f5d537ffcca1ba933f9f0a968aa022 Mon Sep 17 00:00:00 2001
From: Keith Packard <keithp@keithp.com>
Date: Thu, 18 Jan 2018 17:51:59 -0800
Subject: drm: Check for lessee in DROP_MASTER ioctl

From: Keith Packard <keithp@keithp.com>

commit 761e05a702f5d537ffcca1ba933f9f0a968aa022 upstream.

Don't let a lessee control what the current DRM master is set to;
that's the job of the "real" master. Otherwise, the lessee would
disable all access to master operations for the owner and all lessees
under it.

This matches the same check made in the SET_MASTER ioctl.

Signed-off-by: Keith Packard <keithp@keithp.com>
Fixes: 2ed077e467ee ("drm: Add drm_object lease infrastructure [v5]")
Cc: <stable@vger.kernel.org> # v4.15+
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180119015159.1606-1-keithp@keithp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/drm_auth.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/gpu/drm/drm_auth.c
+++ b/drivers/gpu/drm/drm_auth.c
@@ -230,6 +230,12 @@ int drm_dropmaster_ioctl(struct drm_devi
 	if (!dev->master)
 		goto out_unlock;
 
+	if (file_priv->master->lessor != NULL) {
+		DRM_DEBUG_LEASE("Attempt to drop lessee %d as master\n", file_priv->master->lessee_id);
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
 	ret = 0;
 	drm_drop_master(dev, file_priv);
 out_unlock:


Patches currently in stable-queue which might be from keithp@keithp.com are

queue-4.15/drm-check-for-lessee-in-drop_master-ioctl.patch