[PATCH] drm/i915/hdcp: fix connector refcounting - Linux-stable-mirror

24 Sep 2024

We acquire a connector reference before scheduling an HDCP prop work,
and expect the work function to release the reference.
However, if the work was already queued, it won't be queued multiple
times, and the reference is not dropped.
Release the reference immediately if the work was already queued.
Fixes: a6597faa2d59 ("drm/i915: Protect workers against disappearing connectors")
Cc: Sean Paul seanpaul@chromium.org
Cc: Suraj Kandpal suraj.kandpal@intel.com
Cc: Ville Syrjälä ville.syrjala@linux.intel.com
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Jani Nikula jani.nikula@intel.com
---
I don't know that we have any bugs open about this. Or how it would
manifest itself. Memory leak on driver unload? I just spotted this while
reading the code for other reasons.
---
 drivers/gpu/drm/i915/display/intel_hdcp.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
index 2afa92321b08..cad309602617 100644
--- a/drivers/gpu/drm/i915/display/intel_hdcp.c
+++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
@@ -1097,7 +1097,8 @@ static void intel_hdcp_update_value(struct intel_connector *connector,
    hdcp->value = value;
    if (update_property) {
    	drm_connector_get(&connector->base);
-		queue_work(i915->unordered_wq, &hdcp->prop_work);
+		if (!queue_work(i915->unordered_wq, &hdcp->prop_work))
+			drm_connector_put(&connector->base);
    }
 }
@@ -2531,7 +2532,8 @@ void intel_hdcp_update_pipe(struct intel_atomic_state *state,
    	mutex_lock(&hdcp->mutex);
    	hdcp->value = DRM_MODE_CONTENT_PROTECTION_DESIRED;
    	drm_connector_get(&connector->base);
-		queue_work(i915->unordered_wq, &hdcp->prop_work);
+		if (!queue_work(i915->unordered_wq, &hdcp->prop_work))
+			drm_connector_put(&connector->base);
    	mutex_unlock(&hdcp->mutex);
    }
@@ -2548,7 +2550,9 @@ void intel_hdcp_update_pipe(struct intel_atomic_state *state,
    	 */
    	if (!desired_and_not_enabled && !content_protection_type_changed) {
    		drm_connector_get(&connector->base);
-			queue_work(i915->unordered_wq, &hdcp->prop_work);
+			if (!queue_work(i915->unordered_wq, &hdcp->prop_work))
+				drm_connector_put(&connector->base);
+
    	}
    }
-- 
2.39.2



    