Re: [PATCH] drm/mediatek: fix device use-after-free on unbind

[AngeloGioacchino Del Regno]

Il 06/10/25 11:39, Johan Hovold ha scritto:
> 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@xxxxxxxxxxxxx>
> Link: https://lore.kernel.org/r/20251003-mtk-drm-refcount-v1-1-3b3f2813b0db@xxxxxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: Ma Ke <make24@xxxxxxxxxxx>
> Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>

Heh, nice!

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>