leds: leds-st1202: Fix NULL pointer access on race condition

st1202_dt_init() calls devm_led_classdev_register_ext() before the
internal data structures are properly set up, so the LEDs become visible
to user space while being partially initialized, leading to a window
where trying to access them causes a NULL pointer access.

Move devm_led_classdev_register_ext() from DT initialization
to the end of the probe function when DT and hardware are fully
initialized and ready to interact with user space.

Fixes: 259230378c65 ("leds: Add LED1202 I2C driver")
Signed-off-by: Manuel Fombuena <fombuena@outlook.com>
Link: https://lore.kernel.org/r/CWLP123MB54732771AC0CE5491B3C84DCC5C32@CWLP123MB5473.GBRP123.PROD.OUTLOOK.COM
Signed-off-by: Lee Jones <lee@kernel.org>

diff --git a/drivers/leds/leds-st1202.c b/drivers/leds/leds-st1202.c
index b691c4886993f3e371e857543863c9a724742f39..e894b3f9a0f46bae2db33342094268df8d484a98 100644 (file)
--- a/drivers/leds/leds-st1202.c
+++ b/drivers/leds/leds-st1202.c
@@ -261,8 +261,6 @@ static int st1202_dt_init(struct st1202_chip *chip)
        int err, reg;
 
        for_each_available_child_of_node_scoped(dev_of_node(dev), child) {
-               struct led_init_data init_data = {};
-
                err = of_property_read_u32(child, "reg", &reg);
                if (err)
                        return dev_err_probe(dev, err, "Invalid register\n");
@@ -276,15 +274,6 @@ static int st1202_dt_init(struct st1202_chip *chip)
                led->led_cdev.pattern_set = st1202_led_pattern_set;
                led->led_cdev.pattern_clear = st1202_led_pattern_clear;
                led->led_cdev.default_trigger = "pattern";
-
-               init_data.fwnode = led->fwnode;
-               init_data.devicename = "st1202";
-               init_data.default_label = ":";
-
-               err = devm_led_classdev_register_ext(dev, &led->led_cdev, &init_data);
-               if (err < 0)
-                       return dev_err_probe(dev, err, "Failed to register LED class device\n");
-
                led->led_cdev.brightness_set = st1202_brightness_set;
                led->led_cdev.brightness_get = st1202_brightness_get;
        }
@@ -368,6 +357,7 @@ static int st1202_probe(struct i2c_client *client)
                return ret;
 
        for (int i = 0; i < ST1202_MAX_LEDS; i++) {
+               struct led_init_data init_data = {};
                led = &chip->leds[i];
                led->chip = chip;
                led->led_num = i;
@@ -384,6 +374,15 @@ static int st1202_probe(struct i2c_client *client)
                if (ret < 0)
                        return dev_err_probe(&client->dev, ret,
                                        "Failed to clear LED pattern\n");
+
+               init_data.fwnode = led->fwnode;
+               init_data.devicename = "st1202";
+               init_data.default_label = ":";
+
+               ret = devm_led_classdev_register_ext(&client->dev, &led->led_cdev, &init_data);
+               if (ret < 0)
+                       return dev_err_probe(&client->dev, ret,
+                                       "Failed to register LED class device\n");
        }
 
        return 0;