generic: add leds_st1202 patch to fix NULL pointer access

As per @KanjiMonster comment: st1202_dt_init() calls devm_led_classdev_register_ext() before the internal data structures are properly setup, 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() to the last thing to happen during initialization.

Signed-off-by: Manuel Fombuena <fombuena@outlook.com>
Link: https://github.com/openwrt/openwrt/pull/17543


Signed-off-by: Robert Marko <robimarko@gmail.com>

target/linux/generic/pending-6.6/893-leds_st1202-Fix-NULL-pointer-access-error.patch

+From e3da313ebcace17f1227566fe1b0d0c3883061f9 Mon Sep 17 00:00:00 2001
+From: Manuel Fombuena <fombuena@outlook.com>
+Date: Fri, 17 Jan 2025 12:31:49 +0000
+Subject: [PATCH 1/5] 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 setup, 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.
+
+This change moves devm_led_classdev_register_ext() to the last thing to
+happen during initialization to eliminate it.
+
+Signed-off-by: Manuel Fombuena <fombuena@outlook.com>
+---
+ drivers/leds/leds-st1202.c | 21 ++++++++++-----------
+ 1 file changed, 10 insertions(+), 11 deletions(-)
+
+--- a/drivers/leds/leds-st1202.c
++++ b/drivers/leds/leds-st1202.c
+@@ -261,8 +261,6 @@ static int st1202_dt_init(struct st1202_
+ 	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_
+ 		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_clien
+ 		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_clien
+ 		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;