Johan Hovold <[email protected]> 於 2025年10月6日 週一 上午9:48寫道： > > 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.
Applied to mediatek-drm-fixes [1], thanks. [1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/log/?h=mediatek-drm-fixes Regards, Chun-Kuang. > > 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 >
