The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 1f403699c40f0806a707a9a6eed3b8904224021a # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025090146-playback-kinsman-373c@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1f403699c40f0806a707a9a6eed3b8904224021a Mon Sep 17 00:00:00 2001 From: Ma Ke make24@iscas.ac.cn Date: Tue, 12 Aug 2025 15:19:32 +0800 Subject: [PATCH] drm/mediatek: Fix device/node reference count leaks in mtk_drm_get_all_drm_priv

Using device_find_child() and of_find_device_by_node() to locate devices could cause an imbalance in the device's reference count. device_find_child() and of_find_device_by_node() both call get_device() to increment the reference count of the found device before returning the pointer. In mtk_drm_get_all_drm_priv(), these references are never released through put_device(), resulting in permanent reference count increments. Additionally, the for_each_child_of_node() iterator fails to release node references in all code paths. This leaks device node references when loop termination occurs before reaching MAX_CRTC. These reference count leaks may prevent device/node resources from being properly released during driver unbind operations.

As comment of device_find_child() says, 'NOTE: you will need to drop the reference with put_device() after use'.

Cc: stable@vger.kernel.org Fixes: 1ef7ed48356c ("drm/mediatek: Modify mediatek-drm for mt8195 multi mmsys support") Signed-off-by: Ma Ke make24@iscas.ac.cn Reviewed-by: CK Hu ck.hu@mediatek.com Link: https://patchwork.kernel.org/project/dri-devel/patch/20250812071932.471730-1... Signed-off-by: Chun-Kuang Hu chunkuang.hu@kernel.org

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c index d5e6bab36414..f8a817689e16 100644 --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c @@ -387,19 +387,19 @@ static bool mtk_drm_get_all_drm_priv(struct device *dev)

of_id = of_match_node(mtk_drm_of_ids, node); if (!of_id) - continue; + goto next_put_node;

pdev = of_find_device_by_node(node); if (!pdev) - continue; + goto next_put_node;

drm_dev = device_find_child(&pdev->dev, NULL, mtk_drm_match); if (!drm_dev) - continue; + goto next_put_device_pdev_dev;

temp_drm_priv = dev_get_drvdata(drm_dev); if (!temp_drm_priv) - continue; + goto next_put_device_drm_dev;

if (temp_drm_priv->data->main_len) all_drm_priv[CRTC_MAIN] = temp_drm_priv; @@ -411,10 +411,17 @@ static bool mtk_drm_get_all_drm_priv(struct device *dev) if (temp_drm_priv->mtk_drm_bound) cnt++;

- if (cnt == MAX_CRTC) { - of_node_put(node); +next_put_device_drm_dev: + put_device(drm_dev); + +next_put_device_pdev_dev: + put_device(&pdev->dev); + +next_put_node: + of_node_put(node); + + if (cnt == MAX_CRTC) break; - } }

if (drm_priv->data->mmsys_dev_num == cnt) {