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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, Dan Carpenter <dan.carpenter@oracle.com>,
        Guenter Roeck <linux@roeck-us.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 135/171] hwmon: (adt7470) Prevent divide by zero in adt7470_fan_write()
Date:   Mon, 31 Jan 2022 11:56:40 +0100
Message-Id: <20220131105234.571572094@linuxfoundation.org>
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From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit c1ec0cabc36718efc7fe8b4157d41b82d08ec1d2 ]

The "val" variable is controlled by the user and comes from
hwmon_attr_store().  The FAN_RPM_TO_PERIOD() macro divides by "val"
so a zero will crash the system.  Check for that and return -EINVAL.
Negatives are also invalid so return -EINVAL for those too.

Fixes: fc958a61ff6d ("hwmon: (adt7470) Convert to devm_hwmon_device_register_with_info API")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hwmon/adt7470.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/hwmon/adt7470.c b/drivers/hwmon/adt7470.c
index d519aca4a9d64..fb6d14d213a18 100644
--- a/drivers/hwmon/adt7470.c
+++ b/drivers/hwmon/adt7470.c
@@ -662,6 +662,9 @@ static int adt7470_fan_write(struct device *dev, u32 attr, int channel, long val
 	struct adt7470_data *data = dev_get_drvdata(dev);
 	int err;
 
+	if (val <= 0)
+		return -EINVAL;
+
 	val = FAN_RPM_TO_PERIOD(val);
 	val = clamp_val(val, 1, 65534);
 
-- 
2.34.1