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Subject[PATCH v2 2/2] ASoC: mediatek: mt8195: fix use-after-free in driver remove path
Date
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@mediatek.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
---
sound/soc/mediatek/mt8195/mt8195-afe-clk.c | 5 --
sound/soc/mediatek/mt8195/mt8195-afe-clk.h | 1 -
sound/soc/mediatek/mt8195/mt8195-afe-pcm.c | 4 --
sound/soc/mediatek/mt8195/mt8195-audsys-clk.c | 47 ++++++++++---------
sound/soc/mediatek/mt8195/mt8195-audsys-clk.h | 1 -
5 files changed, 24 insertions(+), 34 deletions(-)

diff --git a/sound/soc/mediatek/mt8195/mt8195-afe-clk.c b/sound/soc/mediatek/mt8195/mt8195-afe-clk.c
index 9ca2cb8c8a9c..f35318ae0739 100644
--- a/sound/soc/mediatek/mt8195/mt8195-afe-clk.c
+++ b/sound/soc/mediatek/mt8195/mt8195-afe-clk.c
@@ -410,11 +410,6 @@ int mt8195_afe_init_clock(struct mtk_base_afe *afe)
return 0;
}

-void mt8195_afe_deinit_clock(struct mtk_base_afe *afe)
-{
- mt8195_audsys_clk_unregister(afe);
-}
-
int mt8195_afe_enable_clk(struct mtk_base_afe *afe, struct clk *clk)
{
int ret;
diff --git a/sound/soc/mediatek/mt8195/mt8195-afe-clk.h b/sound/soc/mediatek/mt8195/mt8195-afe-clk.h
index 40663e31becd..a08c0ee6c860 100644
--- a/sound/soc/mediatek/mt8195/mt8195-afe-clk.h
+++ b/sound/soc/mediatek/mt8195/mt8195-afe-clk.h
@@ -101,7 +101,6 @@ int mt8195_afe_get_mclk_source_clk_id(int sel);
int mt8195_afe_get_mclk_source_rate(struct mtk_base_afe *afe, int apll);
int mt8195_afe_get_default_mclk_source_by_rate(int rate);
int mt8195_afe_init_clock(struct mtk_base_afe *afe);
-void mt8195_afe_deinit_clock(struct mtk_base_afe *afe);
int mt8195_afe_enable_clk(struct mtk_base_afe *afe, struct clk *clk);
void mt8195_afe_disable_clk(struct mtk_base_afe *afe, struct clk *clk);
int mt8195_afe_prepare_clk(struct mtk_base_afe *afe, struct clk *clk);
diff --git a/sound/soc/mediatek/mt8195/mt8195-afe-pcm.c b/sound/soc/mediatek/mt8195/mt8195-afe-pcm.c
index d22cf1664d8a..a0f2012211fb 100644
--- a/sound/soc/mediatek/mt8195/mt8195-afe-pcm.c
+++ b/sound/soc/mediatek/mt8195/mt8195-afe-pcm.c
@@ -3224,15 +3224,11 @@ static int mt8195_afe_pcm_dev_probe(struct platform_device *pdev)

static void mt8195_afe_pcm_dev_remove(struct platform_device *pdev)
{
- struct mtk_base_afe *afe = platform_get_drvdata(pdev);
-
snd_soc_unregister_component(&pdev->dev);

pm_runtime_disable(&pdev->dev);
if (!pm_runtime_status_suspended(&pdev->dev))
mt8195_afe_runtime_suspend(&pdev->dev);
-
- mt8195_afe_deinit_clock(afe);
}

static const struct of_device_id mt8195_afe_pcm_dt_match[] = {
diff --git a/sound/soc/mediatek/mt8195/mt8195-audsys-clk.c b/sound/soc/mediatek/mt8195/mt8195-audsys-clk.c
index e0670e0dbd5b..38594bc3f2f7 100644
--- a/sound/soc/mediatek/mt8195/mt8195-audsys-clk.c
+++ b/sound/soc/mediatek/mt8195/mt8195-audsys-clk.c
@@ -148,6 +148,29 @@ static const struct afe_gate aud_clks[CLK_AUD_NR_CLK] = {
GATE_AUD6(CLK_AUD_GASRC19, "aud_gasrc19", "top_asm_h", 19),
};

+static void mt8195_audsys_clk_unregister(void *data)
+{
+ struct mtk_base_afe *afe = data;
+ struct mt8195_afe_private *afe_priv = afe->platform_priv;
+ struct clk *clk;
+ struct clk_lookup *cl;
+ int i;
+
+ if (!afe_priv)
+ return;
+
+ for (i = 0; i < CLK_AUD_NR_CLK; i++) {
+ cl = afe_priv->lookup[i];
+ if (!cl)
+ continue;
+
+ clk = cl->clk;
+ clk_unregister_gate(clk);
+
+ clkdev_drop(cl);
+ }
+}
+
int mt8195_audsys_clk_register(struct mtk_base_afe *afe)
{
struct mt8195_afe_private *afe_priv = afe->platform_priv;
@@ -188,27 +211,5 @@ int mt8195_audsys_clk_register(struct mtk_base_afe *afe)
afe_priv->lookup[i] = cl;
}

- return 0;
-}
-
-void mt8195_audsys_clk_unregister(struct mtk_base_afe *afe)
-{
- struct mt8195_afe_private *afe_priv = afe->platform_priv;
- struct clk *clk;
- struct clk_lookup *cl;
- int i;
-
- if (!afe_priv)
- return;
-
- for (i = 0; i < CLK_AUD_NR_CLK; i++) {
- cl = afe_priv->lookup[i];
- if (!cl)
- continue;
-
- clk = cl->clk;
- clk_unregister_gate(clk);
-
- clkdev_drop(cl);
- }
+ return devm_add_action_or_reset(afe->dev, mt8195_audsys_clk_unregister, afe);
}
diff --git a/sound/soc/mediatek/mt8195/mt8195-audsys-clk.h b/sound/soc/mediatek/mt8195/mt8195-audsys-clk.h
index 239d31016ba7..69db2dd1c9e0 100644
--- a/sound/soc/mediatek/mt8195/mt8195-audsys-clk.h
+++ b/sound/soc/mediatek/mt8195/mt8195-audsys-clk.h
@@ -10,6 +10,5 @@
#define _MT8195_AUDSYS_CLK_H_

int mt8195_audsys_clk_register(struct mtk_base_afe *afe);
-void mt8195_audsys_clk_unregister(struct mtk_base_afe *afe);

#endif
--
2.18.0
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