drm: Fix GETCONNECTOR regression

In

commit f075c227f4b70826bd31d77fa4bbe1f658760b7e
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed Dec 14 00:08:10 2016 +0100

    drm: Tighten locking in drm_mode_getconnector

I reordered the logic a bit in that IOCTL, but that broke userspace
since it'll get the new mode list, but not the new property values.
Fix that again.

v2: Fix up the error path handling when copy_to_user for the modes
failes (Dhinakaran).

Fixes: f075c227f4b7 ("drm: Tighten locking in drm_mode_getconnector")
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org
Reported-by: "H.J. Lu" <hjl.tools@gmail.com>
Tested-by: "H.J. Lu" <hjl.tools@gmail.com>
Cc: <stable@vger.kernel.org> # v4.11+
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100576
Cc: "H.J. Lu" <hjl.tools@gmail.com>
Cc: "Pandiyan, Dhinakaran" <dhinakaran.pandiyan@intel.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170620202837.1701-1-daniel.vetter@ffwll.ch

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 9f847615ac74ab012f6203a141627a5c6f5993e2..48ca2457df8c964977f3f7edae0980bc227b97cf 100644 (file)
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -1229,21 +1229,6 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
        if (!connector)
                return -ENOENT;
 
-       drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
-       encoder = drm_connector_get_encoder(connector);
-       if (encoder)
-               out_resp->encoder_id = encoder->base.id;
-       else
-               out_resp->encoder_id = 0;
-
-       ret = drm_mode_object_get_properties(&connector->base, file_priv->atomic,
-                       (uint32_t __user *)(unsigned long)(out_resp->props_ptr),
-                       (uint64_t __user *)(unsigned long)(out_resp->prop_values_ptr),
-                       &out_resp->count_props);
-       drm_modeset_unlock(&dev->mode_config.connection_mutex);
-       if (ret)
-               goto out_unref;
-
        for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++)
                if (connector->encoder_ids[i] != 0)
                        encoders_count++;
@@ -1256,7 +1241,7 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
                                if (put_user(connector->encoder_ids[i],
                                             encoder_ptr + copied)) {
                                        ret = -EFAULT;
-                                       goto out_unref;
+                                       goto out;
                                }
                                copied++;
                        }
@@ -1300,15 +1285,32 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
                        if (copy_to_user(mode_ptr + copied,
                                         &u_mode, sizeof(u_mode))) {
                                ret = -EFAULT;
+                               mutex_unlock(&dev->mode_config.mutex);
+
                                goto out;
                        }
                        copied++;
                }
        }
        out_resp->count_modes = mode_count;
-out:
        mutex_unlock(&dev->mode_config.mutex);
-out_unref:
+
+       drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
+       encoder = drm_connector_get_encoder(connector);
+       if (encoder)
+               out_resp->encoder_id = encoder->base.id;
+       else
+               out_resp->encoder_id = 0;
+
+       /* Only grab properties after probing, to make sure EDID and other
+        * properties reflect the latest status. */
+       ret = drm_mode_object_get_properties(&connector->base, file_priv->atomic,
+                       (uint32_t __user *)(unsigned long)(out_resp->props_ptr),
+                       (uint64_t __user *)(unsigned long)(out_resp->prop_values_ptr),
+                       &out_resp->count_props);
+       drm_modeset_unlock(&dev->mode_config.connection_mutex);
+
+out:
        drm_connector_put(connector);
 
        return ret;