linux-kernel - [PATCH] backlight: pwm_bl: Avoid open coded arithmetic in memory allocation

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Message-Id: <bd3d74acfa58d59f6f5f81fc5a9fb409edb8d747.1644046817.git.christophe.jaillet@wanadoo.fr>
Date:   Sat,  5 Feb 2022 08:40:48 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, Lee Jones <lee.jones@...aro.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>, Helge Deller <deller@....de>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        linux-pwm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-fbdev@...r.kernel.org
Subject: [PATCH] backlight: pwm_bl: Avoid open coded arithmetic in memory allocation

kmalloc_array()/kcalloc() should be used to avoid potential overflow when
a multiplication is needed to compute the size of the requested memory.

So turn a kzalloc()+explicit size computation into an equivalent kcalloc().

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
 drivers/video/backlight/pwm_bl.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 8d8959a70e44..c0523a0269ee 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -263,9 +263,8 @@ static int pwm_backlight_parse_dt(struct device *dev,
 
 	/* read brightness levels from DT property */
 	if (num_levels > 0) {
-		size_t size = sizeof(*data->levels) * num_levels;
-
-		data->levels = devm_kzalloc(dev, size, GFP_KERNEL);
+		data->levels = devm_kcalloc(dev, num_levels,
+					    sizeof(*data->levels), GFP_KERNEL);
 		if (!data->levels)
 			return -ENOMEM;
 
@@ -320,8 +319,8 @@ static int pwm_backlight_parse_dt(struct device *dev,
 			 * Create a new table of brightness levels with all the
 			 * interpolated steps.
 			 */
-			size = sizeof(*table) * num_levels;
-			table = devm_kzalloc(dev, size, GFP_KERNEL);
+			table = devm_kcalloc(dev, num_levels, sizeof(*table),
+					     GFP_KERNEL);
 			if (!table)
 				return -ENOMEM;
 			/*
-- 
2.32.0