[PATCH v3 1/2] leds: flash: Prevent using uninitialized variable in flash_fault_show()

[PATCH v3 1/2] leds: flash: Prevent using uninitialized variable in flash_fault_show()

[Dmitry Antipov]

In flash_fault_show(), address of uninitialized 'fault' variable is
passed to device-specific .fault_get callbacks. This is not a problem
if such a callback directly assigns the value like rt4505_fault_get(),
but results in an undefined behavior if callback just performs bitwise
ORs like as3645a_get_fault(). So just initialize 'fault' with zero.

Reported-by: sashiko-bot@kernel.org
Closes: https://sashiko.dev/#/patchset/20260904054437.461706-1-dmantipov@yandex.ru?part=1
Fixes: 7aea8389a77ab ("leds: Add LED Flash class extension to the LED subsystem")
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
---
v3: unchanged since v2
v2: initial version to join the series
---
 drivers/leds/led-class-flash.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/leds/led-class-flash.c b/drivers/leds/led-class-flash.c
index 165035a8826c..3bb90823de1a 100644
--- a/drivers/leds/led-class-flash.c
+++ b/drivers/leds/led-class-flash.c
@@ -187,7 +187,7 @@ static ssize_t flash_fault_show(struct device *dev,
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);
 	struct led_classdev_flash *fled_cdev = lcdev_to_flcdev(led_cdev);
-	u32 fault, mask = 0x1;
+	u32 fault = 0, mask = 0x1;
 	char *pbuf = buf;
 	int i, ret, buf_len;
 
-- 
2.55.0

[PATCH v3 2/2] leds: flash: Simplify flash_fault_show()

[Dmitry Antipov]

Do not emit extra trailing space and use sysfs_emit_at()
over sprintf()/strcat()/strlen() in flash_fault_show().

Suggested-by: Lee Jones <lee@kernel.org>
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
---
v3: use sysfs_emit_at() as suggested by Lee
v2: capitalize commit title
---
 drivers/leds/led-class-flash.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/drivers/leds/led-class-flash.c b/drivers/leds/led-class-flash.c
index 3bb90823de1a..181dfd49c6ad 100644
--- a/drivers/leds/led-class-flash.c
+++ b/drivers/leds/led-class-flash.c
@@ -188,25 +188,22 @@ static ssize_t flash_fault_show(struct device *dev,
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);
 	struct led_classdev_flash *fled_cdev = lcdev_to_flcdev(led_cdev);
 	u32 fault = 0, mask = 0x1;
-	char *pbuf = buf;
-	int i, ret, buf_len;
+	int i, ret;
 
 	ret = led_get_flash_fault(fled_cdev, &fault);
 	if (ret < 0)
 		return -EINVAL;
 
-	*buf = '\0';
-
-	for (i = 0; i < LED_NUM_FLASH_FAULTS; ++i) {
-		if (fault & mask) {
-			buf_len = sprintf(pbuf, "%s ",
-					  led_flash_fault_names[i]);
-			pbuf += buf_len;
-		}
+	for (ret = 0, i = 0; i < LED_NUM_FLASH_FAULTS; ++i) {
+		if (fault & mask)
+			ret += sysfs_emit_at(buf, ret, "%s%s",
+					     (ret ? " " : ""),
+					     led_flash_fault_names[i]);
 		mask <<= 1;
 	}
 
-	return strlen(strcat(buf, "\n"));
+	ret += sysfs_emit_at(buf, ret, "\n");
+	return ret;
 }
 static DEVICE_ATTR_RO(flash_fault);
 
-- 
2.55.0

Re: [PATCH v3 2/2] leds: flash: Simplify flash_fault_show()

[sashiko-bot]

> Do not emit extra trailing space and use sysfs_emit_at()
> over sprintf()/strcat()/strlen() in flash_fault_show().
> 
> Suggested-by: Lee Jones <lee@kernel.org>
> Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260916161607.90106-1-dmantipov@yandex.ru?part=2

Re: [PATCH v3 1/2] leds: flash: Prevent using uninitialized variable in flash_fault_show()

[sashiko-bot]

> In flash_fault_show(), address of uninitialized 'fault' variable is
> passed to device-specific .fault_get callbacks. This is not a problem
> if such a callback directly assigns the value like rt4505_fault_get(),
> but results in an undefined behavior if callback just performs bitwise
> ORs like as3645a_get_fault(). So just initialize 'fault' with zero.
> 
> Reported-by: sashiko-bot@kernel.org
> Closes: https://sashiko.dev/#/patchset/20260904054437.461706-1-dmantipov@yandex.ru?part=1
> Fixes: 7aea8389a77ab ("leds: Add LED Flash class extension to the LED subsystem")
> Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260916161607.90106-1-dmantipov@yandex.ru?part=1

Re: [PATCH v3 1/2] leds: flash: Prevent using uninitialized variable in flash_fault_show()

[Lee Jones]

On Wed, 16 Sep 2026 19:16:06 +0300, Dmitry Antipov wrote:
> In flash_fault_show(), address of uninitialized 'fault' variable is
> passed to device-specific .fault_get callbacks. This is not a problem
> if such a callback directly assigns the value like rt4505_fault_get(),
> but results in an undefined behavior if callback just performs bitwise
> ORs like as3645a_get_fault(). So just initialize 'fault' with zero.
> 
> 
> [...]

Applied, thanks!

[1/2] leds: flash: Prevent using uninitialized variable in flash_fault_show()
      commit: d229695f2162a41bfa614f175798fa56a5f1c969
[2/2] leds: flash: Simplify flash_fault_show()
      commit: b18158f705dcff53f76f37733dea5154f1b32444

--
Lee Jones [李琼斯]