Re: [PATCH v2 2/2] ASoC: mediatek: mt8195: fix use-after-free in driver remove path

[AngeloGioacchino Del Regno]

Il 01/06/23 05:33, Trevor Wu ha scritto:
> During mt8195_afe_init_clock(), mt8195_audsys_clk_register() was called
> followed by several other devm functions. At mt8195_afe_deinit_clock()
> located at mt8195_afe_pcm_dev_remove(), mt8195_audsys_clk_unregister()
> was called.
>
> However, there was an issue with the order in which these functions were
> called. Specifically, the remove callback of platform_driver was called
> before devres released the resource, resulting in a use-after-free issue
> during remove time.
>
> At probe time, the order of calls was:
> 1. mt8195_audsys_clk_register
> 2. afe_priv->clk = devm_kcalloc
> 3. afe_priv->clk[i] = devm_clk_get
>
> At remove time, the order of calls was:
> 1. mt8195_audsys_clk_unregister
> 3. free afe_priv->clk[i]
> 2. free afe_priv->clk
>
> To resolve the problem, we can utilize devm_add_action_or_reset() in
> mt8195_audsys_clk_register() so that the remove order can be changed to
> 3->2->1.
>
> Fixes: 6746cc858259 ("ASoC: mediatek: mt8195: add platform driver")
> Signed-off-by: Trevor Wu <trevor.wu@xxxxxxxxxxxx>
> Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>

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