drm: Fix GETCONNECTOR regression

In

commit 91eefc05f0ac71902906b2058360e61bd25137fe
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: 91eefc05f0ac ("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

1 files changed, 20 insertions, 18 deletions

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 9f847615ac74..48ca2457df8c 100644
--- 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;