drm: Release reference from blob lookup after replacing property

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().

v2: update credentials, drm_property_unreference_blob() is NULL safe and
NULL is passed consistently to it throughout drm_atomic.c so do so here.

Reported-by: Felix Monninger <felix.monninger@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98420
Signed-off-by: Felix Monninger <felix.monninger@gmail.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@vger.kernel.org
Fixes: 5488dc16fde7 ("drm: introduce pipe color correction properties")
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161025212808.3908-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 23739609427d86b9cd64d81ddad719bf5fc2bd78..e6862a7442104f59fa476a79a28f48bd0daf98a2 100644 (file)
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -420,18 +420,21 @@ 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);
+       drm_property_unreference_blob(new_blob);
 
        return 0;
 }