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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Colin Ian King <colin.king@canonical.com>,
        Stable@vger.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Subject: [PATCH 4.9 36/36] iio: tsl2583: Fix division by a zero lux_val
Date:   Mon, 24 May 2021 17:25:21 +0200
Message-Id: <20210524152325.329346979@linuxfoundation.org>
In-Reply-To: <20210524152324.158146731@linuxfoundation.org>
References: <20210524152324.158146731@linuxfoundation.org>
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From: Colin Ian King <colin.king@canonical.com>

commit af0e1871d79cfbb91f732d2c6fa7558e45c31038 upstream.

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@canonical.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
[Colin Ian King: minor context adjustments for 4.9.y]
Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/staging/iio/light/tsl2583.c |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/drivers/staging/iio/light/tsl2583.c
+++ b/drivers/staging/iio/light/tsl2583.c
@@ -382,6 +382,15 @@ static int taos_als_calibrate(struct iio
 		dev_err(&chip->client->dev, "taos_als_calibrate failed to get lux\n");
 		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->taos_settings.als_cal_target)
 			* chip->taos_settings.als_gain_trim) / lux_val);