linux-kernel - [PATCH] iio: tsl2583: Fix division by a zero lux

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Date:   Fri,  7 May 2021 19:30:41 +0100
From:   Colin King <colin.king@...onical.com>
To:     Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Jon Brenner <jbrenner@...sinc.com>, linux-iio@...r.kernel.org,
        clang-built-linux@...glegroups.com
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] iio: tsl2583: Fix division by a zero lux_val

From: Colin Ian King <colin.king@...onical.com>

The lux_val returned from tsl2583_get_lux can potentially be zero,
so check for this to avoid a division by zero and an overflowed
gain_trim_val.

Fixes clang scan-build warning:

drivers/iio/light/tsl2583.c:345:40: warning: Either the
condition 'lux_val<0' is redundant or there is division
by zero at line 345. [zerodivcond]

Fixes: ac4f6eee8fe8 ("staging: iio: TAOS tsl258x: Device driver")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/iio/light/tsl2583.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/iio/light/tsl2583.c b/drivers/iio/light/tsl2583.c
index 0f787bfc88fc..c9d8f07a6fcd 100644
--- a/drivers/iio/light/tsl2583.c
+++ b/drivers/iio/light/tsl2583.c
@@ -341,6 +341,14 @@ static int tsl2583_als_calibrate(struct iio_dev *indio_dev)
 		return lux_val;
 	}
 
+	/* Avoid division by zero of lux_value later on */
+	if (lux_val == 0) {
+		dev_err(&chip->client->dev,
+			"%s: lux_val of 0 will produce out of range trim_value\n",
+			__func__);
+		return -ENODATA;
+	}
+
 	gain_trim_val = (unsigned int)(((chip->als_settings.als_cal_target)
 			* chip->als_settings.als_gain_trim) / lux_val);
 	if ((gain_trim_val < 250) || (gain_trim_val > 4000)) {
-- 
2.30.2