linux-kernel - [PATCH 08/12] ASoC: cs42l42: Prevent NULL pointer deref in interrupt handler

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Date:   Tue, 10 Aug 2021 16:37:55 +0100
From:   Richard Fitzgerald <rf@...nsource.cirrus.com>
To:     <broonie@...nel.org>
CC:     <alsa-devel@...a-project.org>, <patches@...nsource.cirrus.com>,
        <linux-kernel@...r.kernel.org>,
        Richard Fitzgerald <rf@...nsource.cirrus.com>
Subject: [PATCH 08/12] ASoC: cs42l42: Prevent NULL pointer deref in interrupt handler

The interrupt handling code was getting the struct device* from a
struct snd_soc_component* stored in struct cs42l42_private. If the
interrupt was asserted before ASoC calls component_probe() the
snd_soc_component* will be NULL.

The stored snd_soc_component* is not actually used for anything other
than indirectly getting the struct device*. Remove it, and store the
struct device* in struct cs42l42_private.

Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
---
 sound/soc/codecs/cs42l42.c | 26 ++++++++------------------
 sound/soc/codecs/cs42l42.h |  2 +-
 2 files changed, 9 insertions(+), 19 deletions(-)

diff --git a/sound/soc/codecs/cs42l42.c b/sound/soc/codecs/cs42l42.c
index 0b63dba07b6d..b7a1231add2d 100644
--- a/sound/soc/codecs/cs42l42.c
+++ b/sound/soc/codecs/cs42l42.c
@@ -554,17 +554,7 @@ static int cs42l42_set_jack(struct snd_soc_component *component, struct snd_soc_
 	return 0;
 }
 
-static int cs42l42_component_probe(struct snd_soc_component *component)
-{
-	struct cs42l42_private *cs42l42 = snd_soc_component_get_drvdata(component);
-
-	cs42l42->component = component;
-
-	return 0;
-}
-
 static const struct snd_soc_component_driver soc_component_dev_cs42l42 = {
-	.probe			= cs42l42_component_probe,
 	.set_jack		= cs42l42_set_jack,
 	.dapm_widgets		= cs42l42_dapm_widgets,
 	.num_dapm_widgets	= ARRAY_SIZE(cs42l42_dapm_widgets),
@@ -1416,19 +1406,19 @@ static int cs42l42_handle_button_press(struct cs42l42_private *cs42l42)
 	switch (bias_level) {
 	case 1: /* Function C button press */
 		bias_level = SND_JACK_BTN_2;
-		dev_dbg(cs42l42->component->dev, "Function C button press\n");
+		dev_dbg(cs42l42->dev, "Function C button press\n");
 		break;
 	case 2: /* Function B button press */
 		bias_level = SND_JACK_BTN_1;
-		dev_dbg(cs42l42->component->dev, "Function B button press\n");
+		dev_dbg(cs42l42->dev, "Function B button press\n");
 		break;
 	case 3: /* Function D button press */
 		bias_level = SND_JACK_BTN_3;
-		dev_dbg(cs42l42->component->dev, "Function D button press\n");
+		dev_dbg(cs42l42->dev, "Function D button press\n");
 		break;
 	case 4: /* Function A button press */
 		bias_level = SND_JACK_BTN_0;
-		dev_dbg(cs42l42->component->dev, "Function A button press\n");
+		dev_dbg(cs42l42->dev, "Function A button press\n");
 		break;
 	default:
 		bias_level = 0;
@@ -1502,7 +1492,6 @@ static const struct cs42l42_irq_params irq_params_table[] = {
 static irqreturn_t cs42l42_irq_thread(int irq, void *data)
 {
 	struct cs42l42_private *cs42l42 = (struct cs42l42_private *)data;
-	struct snd_soc_component *component = cs42l42->component;
 	unsigned int stickies[12];
 	unsigned int masks[12];
 	unsigned int current_plug_status;
@@ -1549,7 +1538,7 @@ static irqreturn_t cs42l42_irq_thread(int irq, void *data)
 			default:
 				break;
 			}
-			dev_dbg(component->dev, "Auto detect done (%d)\n", cs42l42->hs_type);
+			dev_dbg(cs42l42->dev, "Auto detect done (%d)\n", cs42l42->hs_type);
 		}
 	}
 
@@ -1583,7 +1572,7 @@ static irqreturn_t cs42l42_irq_thread(int irq, void *data)
 						    SND_JACK_BTN_0 | SND_JACK_BTN_1 |
 						    SND_JACK_BTN_2 | SND_JACK_BTN_3);
 
-				dev_dbg(component->dev, "Unplug event\n");
+				dev_dbg(cs42l42->dev, "Unplug event\n");
 			}
 			break;
 
@@ -1599,7 +1588,7 @@ static irqreturn_t cs42l42_irq_thread(int irq, void *data)
 			CS42L42_M_HSBIAS_HIZ_MASK)) {
 
 			if (current_button_status & CS42L42_M_DETECT_TF_MASK) {
-				dev_dbg(component->dev, "Button released\n");
+				dev_dbg(cs42l42->dev, "Button released\n");
 				report = 0;
 			} else if (current_button_status & CS42L42_M_DETECT_FT_MASK) {
 				report = cs42l42_handle_button_press(cs42l42);
@@ -1953,6 +1942,7 @@ static int cs42l42_i2c_probe(struct i2c_client *i2c_client,
 	if (!cs42l42)
 		return -ENOMEM;
 
+	cs42l42->dev = &i2c_client->dev;
 	i2c_set_clientdata(i2c_client, cs42l42);
 
 	cs42l42->regmap = devm_regmap_init_i2c(i2c_client, &cs42l42_regmap);
diff --git a/sound/soc/codecs/cs42l42.h b/sound/soc/codecs/cs42l42.h
index d13749e9d8c5..a1e6d443b489 100644
--- a/sound/soc/codecs/cs42l42.h
+++ b/sound/soc/codecs/cs42l42.h
@@ -774,7 +774,7 @@ static const char *const cs42l42_supply_names[CS42L42_NUM_SUPPLIES] = {
 
 struct  cs42l42_private {
 	struct regmap *regmap;
-	struct snd_soc_component *component;
+	struct device *dev;
 	struct regulator_bulk_data supplies[CS42L42_NUM_SUPPLIES];
 	struct gpio_desc *reset_gpio;
 	struct completion pdn_done;
-- 
2.11.0