[PATCH] ASoC: mediatek: mt8186: Fix use-after-free in driver remove path
From: Douglas Anderson
Date: Thu May 11 2023 - 12:27:20 EST
When devm runs function in the "remove" path for a device it runs them
in the reverse order. That means that if you have parts of your driver
that aren't using devm or are using "roll your own" devm w/
devm_add_action_or_reset() you need to keep that in mind.
The mt8186 audio driver didn't quite get this right. Specifically, in
mt8186_init_clock() it called mt8186_audsys_clk_register() and then
went on to call a bunch of other devm function. The caller of
mt8186_init_clock() used devm_add_action_or_reset() to call
mt8186_deinit_clock() but, because of the intervening devm functions,
the order was wrong.
Specifically at probe time, the order was:
1. mt8186_audsys_clk_register()
2. afe_priv->clk = devm_kcalloc(...)
3. afe_priv->clk[i] = devm_clk_get(...)
At remove time, the order (which should have been 3, 2, 1) was:
1. mt8186_audsys_clk_unregister()
3. Free all of afe_priv->clk[i]
2. Free afe_priv->clk
The above seemed to be causing a use-after-free. Luckily, it's easy to
fix this by simply using devm more correctly. Let's move the
devm_add_action_or_reset() to the right place. In addition to fixing
the use-after-free, code inspection shows that this fixes a leak
(missing call to mt8186_audsys_clk_unregister()) that would have
happened if any of the syscon_regmap_lookup_by_phandle() calls in
mt8186_init_clock() had failed.
Fixes: 55b423d5623c ("ASoC: mediatek: mt8186: support audio clock control in platform driver")
Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
---
sound/soc/mediatek/mt8186/mt8186-afe-clk.c | 6 ---
sound/soc/mediatek/mt8186/mt8186-afe-clk.h | 1 -
sound/soc/mediatek/mt8186/mt8186-afe-pcm.c | 4 --
sound/soc/mediatek/mt8186/mt8186-audsys-clk.c | 46 ++++++++++---------
sound/soc/mediatek/mt8186/mt8186-audsys-clk.h | 1 -
5 files changed, 24 insertions(+), 34 deletions(-)
diff --git a/sound/soc/mediatek/mt8186/mt8186-afe-clk.c b/sound/soc/mediatek/mt8186/mt8186-afe-clk.c
index a6b4f29049bb..539e3a023bc4 100644
--- a/sound/soc/mediatek/mt8186/mt8186-afe-clk.c
+++ b/sound/soc/mediatek/mt8186/mt8186-afe-clk.c
@@ -644,9 +644,3 @@ int mt8186_init_clock(struct mtk_base_afe *afe)
return 0;
}
-
-void mt8186_deinit_clock(void *priv)
-{
- struct mtk_base_afe *afe = priv;
- mt8186_audsys_clk_unregister(afe);
-}
diff --git a/sound/soc/mediatek/mt8186/mt8186-afe-clk.h b/sound/soc/mediatek/mt8186/mt8186-afe-clk.h
index d5988717d8f2..a9d59e506d9a 100644
--- a/sound/soc/mediatek/mt8186/mt8186-afe-clk.h
+++ b/sound/soc/mediatek/mt8186/mt8186-afe-clk.h
@@ -81,7 +81,6 @@ enum {
struct mtk_base_afe;
int mt8186_set_audio_int_bus_parent(struct mtk_base_afe *afe, int clk_id);
int mt8186_init_clock(struct mtk_base_afe *afe);
-void mt8186_deinit_clock(void *priv);
int mt8186_afe_enable_cgs(struct mtk_base_afe *afe);
void mt8186_afe_disable_cgs(struct mtk_base_afe *afe);
int mt8186_afe_enable_clock(struct mtk_base_afe *afe);
diff --git a/sound/soc/mediatek/mt8186/mt8186-afe-pcm.c b/sound/soc/mediatek/mt8186/mt8186-afe-pcm.c
index 41172a82103e..a868a04ed4e7 100644
--- a/sound/soc/mediatek/mt8186/mt8186-afe-pcm.c
+++ b/sound/soc/mediatek/mt8186/mt8186-afe-pcm.c
@@ -2848,10 +2848,6 @@ static int mt8186_afe_pcm_dev_probe(struct platform_device *pdev)
return ret;
}
- ret = devm_add_action_or_reset(dev, mt8186_deinit_clock, (void *)afe);
- if (ret)
- return ret;
-
/* init memif */
afe->memif_32bit_supported = 0;
afe->memif_size = MT8186_MEMIF_NUM;
diff --git a/sound/soc/mediatek/mt8186/mt8186-audsys-clk.c b/sound/soc/mediatek/mt8186/mt8186-audsys-clk.c
index 578969ca91c8..5666be6b1bd2 100644
--- a/sound/soc/mediatek/mt8186/mt8186-audsys-clk.c
+++ b/sound/soc/mediatek/mt8186/mt8186-audsys-clk.c
@@ -84,6 +84,29 @@ static const struct afe_gate aud_clks[CLK_AUD_NR_CLK] = {
GATE_AUD2(CLK_AUD_ETDM_OUT1_BCLK, "aud_etdm_out1_bclk", "top_audio", 24),
};
+static void mt8186_audsys_clk_unregister(void *data)
+{
+ struct mtk_base_afe *afe = data;
+ struct mt8186_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 mt8186_audsys_clk_register(struct mtk_base_afe *afe)
{
struct mt8186_afe_private *afe_priv = afe->platform_priv;
@@ -124,27 +147,6 @@ int mt8186_audsys_clk_register(struct mtk_base_afe *afe)
afe_priv->lookup[i] = cl;
}
- return 0;
+ return devm_add_action_or_reset(afe->dev, mt8186_audsys_clk_unregister, afe);
}
-void mt8186_audsys_clk_unregister(struct mtk_base_afe *afe)
-{
- struct mt8186_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);
- }
-}
diff --git a/sound/soc/mediatek/mt8186/mt8186-audsys-clk.h b/sound/soc/mediatek/mt8186/mt8186-audsys-clk.h
index b8d6a06e11e8..897a2914dc19 100644
--- a/sound/soc/mediatek/mt8186/mt8186-audsys-clk.h
+++ b/sound/soc/mediatek/mt8186/mt8186-audsys-clk.h
@@ -10,6 +10,5 @@
#define _MT8186_AUDSYS_CLK_H_
int mt8186_audsys_clk_register(struct mtk_base_afe *afe);
-void mt8186_audsys_clk_unregister(struct mtk_base_afe *afe);
#endif
--
2.40.1.606.ga4b1b128d6-goog