[PATCH v2] drm/nouveau: Fix refcount leak in nouveau_connector_detect

[Shuhao Fu <sfual@cse.ust.hk>]

A possible inconsistent refcount update has been identified in function
`nouveau_connector_detect`, which may cause a resource leak.

After calling `pm_runtime_get_*(dev->dev)`, the usage counter of `dev->dev`
gets increased. In case function `nvif_outp_edid_get` returns negative,
function `nouveau_connector_detect` returns without decreasing the usage
counter of `dev->dev`, causing a refcount inconsistency.

Signed-off-by: Shuhao Fu <sfual@cse.ust.hk>
Closes: https://gitlab.freedesktop.org/drm/nouveau/-/issues/450
Fixes: 0cd7e0718139 ("drm/nouveau/disp: add output method to fetch edid")
Cc: stable@vger.kernel.org

Change in v2:
- Add "Fixes" and "Cc" tags
---
 drivers/gpu/drm/nouveau/nouveau_connector.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 63621b151..45caccade 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -600,8 +600,10 @@ nouveau_connector_detect(struct drm_connector *connector, bool force)
                                new_edid = drm_get_edid(connector, nv_encoder->i2c);
                } else {
                        ret = nvif_outp_edid_get(&nv_encoder->outp, (u8 **)&new_edid);
-                       if (ret < 0)
-                               return connector_status_disconnected;
+                       if (ret < 0) {
+                               conn_status = connector_status_disconnected;
+                               goto out;
+                       }
                }

                nouveau_connector_set_edid(nv_connector, new_edid);
--
2.39.5