[PATCH 4.11 52/58] drm: Fix GETCONNECTOR regression

Greg Kroah-Hartman
2017-06-27T14:20:46Z

From: Daniel Vetter <daniel.vetter@ffwll.ch>

commit e94ac3510b6a0f696f2c442c4fc4051c8101ef12 upstream.

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>
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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/drm_connector.c | 38 ++++++++++++++++++++------------------
1 file changed, 20 insertions(+), 18 deletions(-)

--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -1169,21 +1169,6 @@ int drm_mode_getconnector(struct drm_dev
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++;
@@ -1196,7 +1181,7 @@ int drm_mode_getconnector(struct drm_dev
if (put_user(connector->encoder_ids[i],
encoder_ptr + copied)) {
ret = -EFAULT;
- goto out_unref;
+ goto out;
}
copied++;
}
@@ -1240,15 +1225,32 @@ int drm_mode_getconnector(struct drm_dev
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_unreference(connector);

return ret;