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drm/mediatek: fix potential OF node use-after-free 

commit 4de37a48b6 upstream.

The for_each_child_of_node() helper drops the reference it takes to each
node as it iterates over children and an explicit of_node_put() is only
needed when exiting the loop early.

Drop the recently introduced bogus additional reference count decrement
at each iteration that could potentially lead to a use-after-free.

Fixes: 1f403699c4 ("drm/mediatek: Fix device/node reference count leaks in mtk_drm_get_all_drm_priv")
Cc: Ma Ke <make24@iscas.ac.cn>
Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20250829090345.21075-2-johan@kernel.org/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2025-08-29 11:03:44 +02:00 committed by Greg Kroah-Hartman
parent af0ae62b93
commit b58a26cdd4
1 changed files with 5 additions and 6 deletions
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11
drivers/gpu/drm/mediatek/mtk_drm_drv.c
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@ -381,11 +381,11 @@ static bool mtk_drm_get_all_drm_priv(struct device *dev)
of_id = of_match_node(mtk_drm_of_ids, node);
if (!of_id)
goto next_put_node;
continue;
pdev = of_find_device_by_node(node);
if (!pdev)
goto next_put_node;
continue;
drm_dev = device_find_child(&pdev->dev, NULL, mtk_drm_match);
if (!drm_dev)
@ -411,11 +411,10 @@ next_put_device_drm_dev:
next_put_device_pdev_dev:
put_device(&pdev->dev);
next_put_node:
of_node_put(node);
if (cnt == MAX_CRTC)
if (cnt == MAX_CRTC) {
of_node_put(node);
break;
}
}
if (drm_priv->data->mmsys_dev_num == cnt) {