diff options
| author | Johan Hovold <johan@kernel.org> | 2025-10-06 11:39:37 +0200 |
|---|---|---|
| committer | Chun-Kuang Hu <chunkuang.hu@kernel.org> | 2025-10-28 14:56:16 +0000 |
| commit | 926d002e6d7e2f1fd5c1b53cf6208153ee7d380d (patch) | |
| tree | f12bf095a0cc3a5cf7407e27169832724a656b6b /drivers | |
| parent | 3a8660878839faadb4f1a6dd72c3179c1df56787 (diff) | |
drm/mediatek: Fix device use-after-free on unbind
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 <sjoerd@collabora.com>
Closes: https://lore.kernel.org/r/20251003-mtk-drm-refcount-v1-1-3b3f2813b0db@collabora.com
Cc: stable@vger.kernel.org
Cc: Ma Ke <make24@iscas.ac.cn>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Sjoerd Simons <sjoerd@collabora.com>
Tested-by: Sjoerd Simons <sjoerd@collabora.com>
Tested-by: Ritesh Raj Sarraf <ritesh.sarraf@collabora.com>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20251006093937.27869-1-johan@kernel.org/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/gpu/drm/mediatek/mtk_drm_drv.c | 10 |
1 files changed, 0 insertions, 10 deletions
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c index eb5537f0ac90..31ff2922758a 100644 --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c @@ -686,10 +686,6 @@ err_free: 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 @@ err_put_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; |