linux-kernel - [PATCH] leds: lp55xx: Fix check for invalid channel number

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Message-Id: <1728464547-31722-1-git-send-email-michal.vokac@ysoft.com>
Date: Wed,  9 Oct 2024 11:02:27 +0200
From: Michal Vokáč <michal.vokac@...ft.com>
To: Pavel Machek <pavel@....cz>,
	Lee Jones <lee@...nel.org>
Cc: Dan Murphy <dmurphy@...com>,
	Jacek Anaszewski <jacek.anaszewski@...il.com>,
	linux-leds@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Michal Vokáč <michal.vokac@...ft.com>,
	<stable@...r.kernel.org>
Subject: [PATCH] leds: lp55xx: Fix check for invalid channel number

Prior to commit 92a81562e695 ("leds: lp55xx: Add multicolor framework
support to lp55xx") the reg property (chan_nr) was parsed and stored
as it was. Then, in lp55xx_init_led() function, it was checked if it
is within valid range. In case it was not, an error message was
printed and the driver probe failed.

With the mentioned commit the reg property is checked right after it
is read from the device tree. Comparison to the upper range is not
correct though. Valid reg values are 0 to (max_channel - 1). So in
case the parsed value is out of this (wrong) range the probe just
fails and no error message is shown.

Fix it by using proper comparison and print a message in case of
an error. The check that is done in lp55xx_init_led() function is now
redundant and can be removed.

Fixes: 92a81562e695 ("leds: lp55xx: Add multicolor framework support to lp55xx")
Cc: <stable@...r.kernel.org>
Signed-off-by: Michal Vokáč <michal.vokac@...ft.com>
---
 drivers/leds/leds-lp55xx-common.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/leds/leds-lp55xx-common.c b/drivers/leds/leds-lp55xx-common.c
index 5a2e259679cf..055ee77455f9 100644
--- a/drivers/leds/leds-lp55xx-common.c
+++ b/drivers/leds/leds-lp55xx-common.c
@@ -512,12 +512,6 @@ static int lp55xx_init_led(struct lp55xx_led *led,
 	led->max_current = pdata->led_config[chan].max_current;
 	led->chan_nr = pdata->led_config[chan].chan_nr;

-	if (led->chan_nr >= max_channel) {
-		dev_err(dev, "Use channel numbers between 0 and %d\n",
-			max_channel - 1);
-		return -EINVAL;
-	}
-
 	if (pdata->led_config[chan].num_colors > 1)
 		ret = devm_led_classdev_multicolor_register(dev, &led->mc_cdev);
 	else
@@ -1132,8 +1126,11 @@ static int lp55xx_parse_common_child(struct device_node *np,
 	if (ret)
 		return ret;

-	if (*chan_nr < 0 || *chan_nr > cfg->max_channel)
+	if (*chan_nr < 0 || *chan_nr >= cfg->max_channel) {
+		dev_err(dev, "Use channel numbers between 0 and %d\n",
+			cfg->max_channel - 1);
 		return -EINVAL;
+	}

 	return 0;
 }
-- 
2.1.4