This is a note to let you know that I've just added the patch titled
drm/atomic_helper: Disallow new modesets on unregistered connectors
to the 4.19-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-atomic_helper-disallow-new-modesets-on-unregiste.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c088976472ee5c46b5355b4091fe7e6cd4dc67de
Author: Lyude Paul <lyude@xxxxxxxxxx>
Date: Mon Oct 8 19:24:30 2018 -0400
drm/atomic_helper: Disallow new modesets on unregistered connectors
[ Upstream commit 4d80273976bf880c4bed9359b8f2d45663140c86 ]
With the exception of modesets which would switch the DPMS state of a
connector from on to off, we want to make sure that we disallow all
modesets which would result in enabling a new monitor or a new mode
configuration on a monitor if the connector for the display in question
is no longer registered. This allows us to stop userspace from trying to
enable new displays on connectors for an MST topology that were just
removed from the system, without preventing userspace from disabling
DPMS on those connectors.
Changes since v5:
- Fix typo in comment, nothing else
Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://patchwork.freedesktop.org/patch/msgid/20181008232437.5571-2-lyude@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index c22062cc99923..71c70a031a043 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -307,6 +307,26 @@ update_connector_routing(struct drm_atomic_state *state,
return 0;
}
+ crtc_state = drm_atomic_get_new_crtc_state(state,
+ new_connector_state->crtc);
+ /*
+ * For compatibility with legacy users, we want to make sure that
+ * we allow DPMS On->Off modesets on unregistered connectors. Modesets
+ * which would result in anything else must be considered invalid, to
+ * avoid turning on new displays on dead connectors.
+ *
+ * Since the connector can be unregistered at any point during an
+ * atomic check or commit, this is racy. But that's OK: all we care
+ * about is ensuring that userspace can't do anything but shut off the
+ * display on a connector that was destroyed after its been notified,
+ * not before.
+ */
+ if (!READ_ONCE(connector->registered) && crtc_state->active) {
+ DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] is not registered\n",
+ connector->base.id, connector->name);
+ return -EINVAL;
+ }
+
funcs = connector->helper_private;
if (funcs->atomic_best_encoder)
@@ -351,7 +371,6 @@ update_connector_routing(struct drm_atomic_state *state,
set_best_encoder(state, new_connector_state, new_encoder);
- crtc_state = drm_atomic_get_new_crtc_state(state, new_connector_state->crtc);
crtc_state->connectors_changed = true;
DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] using [ENCODER:%d:%s] on [CRTC:%d:%s]\n",
