A recent change fixed device reference leaks when looking up drm
platform device driver data during bind() but failed to remove a partial
fix which had been added by commit 80805b62ea5b ("drm/mediatek: Fix
kobject put for component sub-drivers").
This results in a reference imbalance on component bind() failures and
on unbind() which could lead to a user-after-free.
Make sure to only drop the references after retrieving the driver data
by effectively reverting the previous partial fix.
Note that holding a reference to a device does not prevent its driver
data from going away so there is no point in keeping the reference.
Fixes: 1f403699c40f ("drm/mediatek: Fix device/node reference count leaks in
mtk_drm_get_all_drm_priv")
Reported-by: Sjoerd Simons <[email protected]>
Link:
https://lore.kernel.org/r/[email protected]
Cc: [email protected]
Cc: Ma Ke <[email protected]>
Cc: AngeloGioacchino Del Regno <[email protected]>
Signed-off-by: Johan Hovold <[email protected]>
---
drivers/gpu/drm/mediatek/mtk_drm_drv.c | 10 ----------
1 file changed, 10 deletions(-)
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
index 384b0510272c..a94c51a83261 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
@@ -686,10 +686,6 @@ static int mtk_drm_bind(struct device *dev)
for (i = 0; i < private->data->mmsys_dev_num; i++)
private->all_drm_private[i]->drm = NULL;
err_put_dev:
- for (i = 0; i < private->data->mmsys_dev_num; i++) {
- /* For device_find_child in mtk_drm_get_all_priv() */
- put_device(private->all_drm_private[i]->dev);
- }
put_device(private->mutex_dev);
return ret;
}
@@ -697,18 +693,12 @@ static int mtk_drm_bind(struct device *dev)
static void mtk_drm_unbind(struct device *dev)
{
struct mtk_drm_private *private = dev_get_drvdata(dev);
- int i;
/* for multi mmsys dev, unregister drm dev in mmsys master */
if (private->drm_master) {
drm_dev_unregister(private->drm);
mtk_drm_kms_deinit(private->drm);
drm_dev_put(private->drm);
-
- for (i = 0; i < private->data->mmsys_dev_num; i++) {
- /* For device_find_child in mtk_drm_get_all_priv() */
- put_device(private->all_drm_private[i]->dev);
- }
put_device(private->mutex_dev);
}
private->mtk_drm_bound = false;
--
2.49.1
