[PATCH 1/2] ASoC: mediatek: mt8188: fix use-after-free in driver remove path

[Trevor Wu]

During mt8188_afe_init_clock(), mt8188_audsys_clk_register() was called
followed by several other devm functions. The caller of
mt8188_afe_init_clock() utilized devm_add_action_or_reset() to call
mt8188_afe_deinit_clock(). However, the order was incorrect, causing a
use-after-free issue during remove time.

At probe time, the order of calls was:
1. mt8188_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. mt8188_audsys_clk_unregister
3. free afe_priv->clk[i]
2. free afe_priv->clk

To resolve the problem, it's necessary to move devm_add_action_or_reset()
to the appropriate position so that the remove order can be 3->2->1.

Fixes: f6b026479b13 ("ASoC: mediatek: mt8188: support audio clock control")
Signed-off-by: Trevor Wu <trevor.wu at mediatek.com>
---
 sound/soc/mediatek/mt8188/mt8188-afe-clk.c    |  7 ---
 sound/soc/mediatek/mt8188/mt8188-afe-clk.h    |  1 -
 sound/soc/mediatek/mt8188/mt8188-afe-pcm.c    |  4 --
 sound/soc/mediatek/mt8188/mt8188-audsys-clk.c | 47 ++++++++++---------
 sound/soc/mediatek/mt8188/mt8188-audsys-clk.h |  1 -
 5 files changed, 24 insertions(+), 36 deletions(-)

diff --git a/sound/soc/mediatek/mt8188/mt8188-afe-clk.c b/sound/soc/mediatek/mt8188/mt8188-afe-clk.c
index 4c24d0b9e90d..e69c1bb2cb23 100644
--- a/sound/soc/mediatek/mt8188/mt8188-afe-clk.c
+++ b/sound/soc/mediatek/mt8188/mt8188-afe-clk.c
@@ -436,13 +436,6 @@ int mt8188_afe_init_clock(struct mtk_base_afe *afe)
 	return 0;
 }
 
-void mt8188_afe_deinit_clock(void *priv)
-{
-	struct mtk_base_afe *afe = priv;
-
-	mt8188_audsys_clk_unregister(afe);
-}
-
 int mt8188_afe_enable_clk(struct mtk_base_afe *afe, struct clk *clk)
 {
 	int ret;
diff --git a/sound/soc/mediatek/mt8188/mt8188-afe-clk.h b/sound/soc/mediatek/mt8188/mt8188-afe-clk.h
index 904505d10841..ec53c171c170 100644
--- a/sound/soc/mediatek/mt8188/mt8188-afe-clk.h
+++ b/sound/soc/mediatek/mt8188/mt8188-afe-clk.h
@@ -111,7 +111,6 @@ int mt8188_afe_get_default_mclk_source_by_rate(int rate);
 int mt8188_get_apll_by_rate(struct mtk_base_afe *afe, int rate);
 int mt8188_get_apll_by_name(struct mtk_base_afe *afe, const char *name);
 int mt8188_afe_init_clock(struct mtk_base_afe *afe);
-void mt8188_afe_deinit_clock(void *priv);
 int mt8188_afe_enable_clk(struct mtk_base_afe *afe, struct clk *clk);
 void mt8188_afe_disable_clk(struct mtk_base_afe *afe, struct clk *clk);
 int mt8188_afe_set_clk_rate(struct mtk_base_afe *afe, struct clk *clk,
diff --git a/sound/soc/mediatek/mt8188/mt8188-afe-pcm.c b/sound/soc/mediatek/mt8188/mt8188-afe-pcm.c
index c3fd32764da0..6a24b339444b 100644
--- a/sound/soc/mediatek/mt8188/mt8188-afe-pcm.c
+++ b/sound/soc/mediatek/mt8188/mt8188-afe-pcm.c
@@ -3256,10 +3256,6 @@ static int mt8188_afe_pcm_dev_probe(struct platform_device *pdev)
 	if (ret)
 		return dev_err_probe(dev, ret, "init clock error");
 
-	ret = devm_add_action_or_reset(dev, mt8188_afe_deinit_clock, (void *)afe);
-	if (ret)
-		return ret;
-
 	spin_lock_init(&afe_priv->afe_ctrl_lock);
 
 	mutex_init(&afe->irq_alloc_lock);
diff --git a/sound/soc/mediatek/mt8188/mt8188-audsys-clk.c b/sound/soc/mediatek/mt8188/mt8188-audsys-clk.c
index be1c53bf4729..05d6f9d78e10 100644
--- a/sound/soc/mediatek/mt8188/mt8188-audsys-clk.c
+++ b/sound/soc/mediatek/mt8188/mt8188-audsys-clk.c
@@ -138,6 +138,29 @@ static const struct afe_gate aud_clks[CLK_AUD_NR_CLK] = {
 	GATE_AUD6(CLK_AUD_GASRC11, "aud_gasrc11", "top_asm_h", 11),
 };
 
+static void mt8188_audsys_clk_unregister(void *data)
+{
+	struct mtk_base_afe *afe = (struct mtk_base_afe *)data;
+	struct mt8188_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 mt8188_audsys_clk_register(struct mtk_base_afe *afe)
 {
 	struct mt8188_afe_private *afe_priv = afe->platform_priv;
@@ -179,27 +202,5 @@ int mt8188_audsys_clk_register(struct mtk_base_afe *afe)
 		afe_priv->lookup[i] = cl;
 	}
 
-	return 0;
-}
-
-void mt8188_audsys_clk_unregister(struct mtk_base_afe *afe)
-{
-	struct mt8188_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, mt8188_audsys_clk_unregister, afe);
 }
diff --git a/sound/soc/mediatek/mt8188/mt8188-audsys-clk.h b/sound/soc/mediatek/mt8188/mt8188-audsys-clk.h
index 6c5f463ad7e4..45b0948c4a06 100644
--- a/sound/soc/mediatek/mt8188/mt8188-audsys-clk.h
+++ b/sound/soc/mediatek/mt8188/mt8188-audsys-clk.h
@@ -10,6 +10,5 @@
 #define _MT8188_AUDSYS_CLK_H_
 
 int mt8188_audsys_clk_register(struct mtk_base_afe *afe);
-void mt8188_audsys_clk_unregister(struct mtk_base_afe *afe);
 
 #endif
-- 
2.18.0