[PATCH] drm: Release reference from blob lookup after replacing property

[Chris Wilson]

drm_property_lookup_blob() returns a reference to the returned blob, and
drm_atomic_replace_property_blob() takes a references to the blob it
stores, so afterwards we are left owning a reference to the new_blob that
we never release, and thus leak memory every time we update a property
such as during drm_atomic_helper_legacy_gamma_set().

Based on a patch by Felix Monninger <felix.monninger at gmail.com>

Reported-by: Felix Monninger <felix.monninger at gmail.com>
References: https://bugs.freedesktop.org/show_bug.cgi?id=98420
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/drm_atomic.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 1b5a32df9a9a..3b35ab793100 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -416,19 +416,24 @@ drm_atomic_replace_property_blob_from_id(struct drm_crtc *crtc,
 					 ssize_t expected_size,
 					 bool *replaced)
 {
-	struct drm_device *dev = crtc->dev;
 	struct drm_property_blob *new_blob = NULL;
 
 	if (blob_id != 0) {
-		new_blob = drm_property_lookup_blob(dev, blob_id);
+		new_blob = drm_property_lookup_blob(crtc->dev, blob_id);
 		if (new_blob == NULL)
 			return -EINVAL;
-		if (expected_size > 0 && expected_size != new_blob->length)
+
+		if (expected_size > 0 && expected_size != new_blob->length) {
+			drm_property_unreference_blob(new_blob);
 			return -EINVAL;
+		}
 	}
 
 	drm_atomic_replace_property_blob(blob, new_blob, replaced);
 
+	if (new_blob)
+		drm_property_unreference_blob(new_blob);
+
 	return 0;
 }
 
-- 
2.10.1