Input: adp5588-keypad - fix NULL dereference in adp5588_gpio_add()

The kpad structure is assigned to i2c client via i2s_set_clientdata()
at the end of adp5588_probe(), but in adp5588_gpio_add() we tried to
access it (via dev_get_drvdata! which is not nice at all) causing an
oops.

Let's pass pointer to kpad directly into adp5588_gpio_add() and
adp5588_gpio_remove() to avoid accessing driver data before it is
set up.

Also split out building of gpiomap into a separate function to
clear the logic.

Reported-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 37 insertions, 29 deletions

diff --git a/drivers/input/keyboard/adp5588-keys.c b/drivers/input/keyboard/adp5588-keys.c
index c39ec93c0c58..d6918cb966c0 100644
--- a/drivers/input/keyboard/adp5588-keys.c
+++ b/drivers/input/keyboard/adp5588-keys.c
@@ -173,41 +173,49 @@ static int adp5588_gpio_direction_output(struct gpio_chip *chip,
         return ret;
 }
 
-static int __devinit adp5588_gpio_add(struct device *dev)
+static int __devinit adp5588_build_gpiomap(struct adp5588_kpad *kpad,
+                                const struct adp5588_kpad_platform_data *pdata)
 {
-        struct adp5588_kpad *kpad = dev_get_drvdata(dev);
-        const struct adp5588_kpad_platform_data *pdata = dev->platform_data;
-        const struct adp5588_gpio_platform_data *gpio_data = pdata->gpio_data;
-        int i, error;
+        bool pin_used[MAXGPIO];
+        int n_unused = 0;
+        int i;
 
-        if (gpio_data) {
-                int j = 0;
-                bool pin_used[MAXGPIO];
+        memset(pin_used, 0, sizeof(pin_used));
 
-                for (i = 0; i < pdata->rows; i++)
-                        pin_used[i] = true;
+        for (i = 0; i < pdata->rows; i++)
+                pin_used[i] = true;
 
-                for (i = 0; i < pdata->cols; i++)
-                        pin_used[i + GPI_PIN_COL_BASE - GPI_PIN_BASE] = true;
+        for (i = 0; i < pdata->cols; i++)
+                pin_used[i + GPI_PIN_COL_BASE - GPI_PIN_BASE] = true;
 
-                for (i = 0; i < kpad->gpimapsize; i++)
-                        pin_used[kpad->gpimap[i].pin - GPI_PIN_BASE] = true;
+        for (i = 0; i < kpad->gpimapsize; i++)
+                pin_used[kpad->gpimap[i].pin - GPI_PIN_BASE] = true;
 
-                for (i = 0; i < MAXGPIO; i++) {
-                        if (!pin_used[i])
-                                kpad->gpiomap[j++] = i;
-                }
-                kpad->gc.ngpio = j;
+        for (i = 0; i < MAXGPIO; i++)
+                if (!pin_used[i])
+                        kpad->gpiomap[n_unused++] = i;
 
-                if (kpad->gc.ngpio)
-                        kpad->export_gpio = true;
-        }
+        return n_unused;
+}
 
-        if (!kpad->export_gpio) {
+static int __devinit adp5588_gpio_add(struct adp5588_kpad *kpad)
+{
+        struct device *dev = &kpad->client->dev;
+        const struct adp5588_kpad_platform_data *pdata = dev->platform_data;
+        const struct adp5588_gpio_platform_data *gpio_data = pdata->gpio_data;
+        int i, error;
+
+        if (!gpio_data)
+                return 0;
+
+        kpad->gc.ngpio = adp5588_build_gpiomap(kpad, pdata);
+        if (kpad->gc.ngpio == 0) {
                 dev_info(dev, "No unused gpios left to export\n");
                 return 0;
         }
 
+        kpad->export_gpio = true;
+
         kpad->gc.direction_input = adp5588_gpio_direction_input;
         kpad->gc.direction_output = adp5588_gpio_direction_output;
         kpad->gc.get = adp5588_gpio_get_value;
@@ -243,9 +251,9 @@ static int __devinit adp5588_gpio_add(struct device *dev)
         return 0;
 }
 
-static void __devexit adp5588_gpio_remove(struct device *dev)
+static void __devexit adp5588_gpio_remove(struct adp5588_kpad *kpad)
 {
-        struct adp5588_kpad *kpad = dev_get_drvdata(dev);
+        struct device *dev = &kpad->client->dev;
         const struct adp5588_kpad_platform_data *pdata = dev->platform_data;
         const struct adp5588_gpio_platform_data *gpio_data = pdata->gpio_data;
         int error;
@@ -266,12 +274,12 @@ static void __devexit adp5588_gpio_remove(struct device *dev)
                 dev_warn(dev, "gpiochip_remove failed %d\n", error);
 }
 #else
-static inline int adp5588_gpio_add(struct device *dev)
+static inline int adp5588_gpio_add(struct adp5588_kpad *kpad)
 {
         return 0;
 }
 
-static inline void adp5588_gpio_remove(struct device *dev)
+static inline void adp5588_gpio_remove(struct adp5588_kpad *kpad)
 {
 }
 #endif
@@ -581,7 +589,7 @@ static int __devinit adp5588_probe(struct i2c_client *client,
         if (kpad->gpimapsize)
                 adp5588_report_switch_state(kpad);
 
-        error = adp5588_gpio_add(&client->dev);
+        error = adp5588_gpio_add(kpad);
         if (error)
                 goto err_free_irq;
 
@@ -611,7 +619,7 @@ static int __devexit adp5588_remove(struct i2c_client *client)
         free_irq(client->irq, kpad);
         cancel_delayed_work_sync(&kpad->work);
         input_unregister_device(kpad->input);
-        adp5588_gpio_remove(&client->dev);
+        adp5588_gpio_remove(kpad);
         kfree(kpad);
 
         return 0;