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    Subject[PATCH 4.9 023/104] hwmon: (gl520sm) Fix overflows and crash seen when writing into limit attributes
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Guenter Roeck <linux@roeck-us.net>


    [ Upstream commit 87cdfa9d60f4f40e6d71b04b10b36d9df3c89282 ]

    Writes into limit attributes can overflow due to multplications and
    additions with unbound input values. Writing into fan limit attributes
    can result in a crash with a division by zero if very large values are
    written and the fan divider is larger than 1.

    Signed-off-by: Guenter Roeck <linux@roeck-us.net>
    Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/hwmon/gl520sm.c | 27 +++++++++++++++++----------
    1 file changed, 17 insertions(+), 10 deletions(-)

    --- a/drivers/hwmon/gl520sm.c
    +++ b/drivers/hwmon/gl520sm.c
    @@ -208,11 +208,13 @@ static ssize_t get_cpu_vid(struct device
    }
    static DEVICE_ATTR(cpu0_vid, S_IRUGO, get_cpu_vid, NULL);

    -#define VDD_FROM_REG(val) (((val) * 95 + 2) / 4)
    -#define VDD_TO_REG(val) clamp_val((((val) * 4 + 47) / 95), 0, 255)
    -
    -#define IN_FROM_REG(val) ((val) * 19)
    -#define IN_TO_REG(val) clamp_val((((val) + 9) / 19), 0, 255)
    +#define VDD_FROM_REG(val) DIV_ROUND_CLOSEST((val) * 95, 4)
    +#define VDD_CLAMP(val) clamp_val(val, 0, 255 * 95 / 4)
    +#define VDD_TO_REG(val) DIV_ROUND_CLOSEST(VDD_CLAMP(val) * 4, 95)
    +
    +#define IN_FROM_REG(val) ((val) * 19)
    +#define IN_CLAMP(val) clamp_val(val, 0, 255 * 19)
    +#define IN_TO_REG(val) DIV_ROUND_CLOSEST(IN_CLAMP(val), 19)

    static ssize_t get_in_input(struct device *dev, struct device_attribute *attr,
    char *buf)
    @@ -349,8 +351,13 @@ static SENSOR_DEVICE_ATTR(in4_max, S_IRU

    #define DIV_FROM_REG(val) (1 << (val))
    #define FAN_FROM_REG(val, div) ((val) == 0 ? 0 : (480000 / ((val) << (div))))
    -#define FAN_TO_REG(val, div) ((val) <= 0 ? 0 : \
    - clamp_val((480000 + ((val) << ((div)-1))) / ((val) << (div)), 1, 255))
    +
    +#define FAN_BASE(div) (480000 >> (div))
    +#define FAN_CLAMP(val, div) clamp_val(val, FAN_BASE(div) / 255, \
    + FAN_BASE(div))
    +#define FAN_TO_REG(val, div) ((val) == 0 ? 0 : \
    + DIV_ROUND_CLOSEST(480000, \
    + FAN_CLAMP(val, div) << (div)))

    static ssize_t get_fan_input(struct device *dev, struct device_attribute *attr,
    char *buf)
    @@ -513,9 +520,9 @@ static SENSOR_DEVICE_ATTR(fan2_div, S_IR
    static DEVICE_ATTR(fan1_off, S_IRUGO | S_IWUSR,
    get_fan_off, set_fan_off);

    -#define TEMP_FROM_REG(val) (((val) - 130) * 1000)
    -#define TEMP_TO_REG(val) clamp_val(((((val) < 0 ? \
    - (val) - 500 : (val) + 500) / 1000) + 130), 0, 255)
    +#define TEMP_FROM_REG(val) (((val) - 130) * 1000)
    +#define TEMP_CLAMP(val) clamp_val(val, -130000, 125000)
    +#define TEMP_TO_REG(val) (DIV_ROUND_CLOSEST(TEMP_CLAMP(val), 1000) + 130)

    static ssize_t get_temp_input(struct device *dev, struct device_attribute *attr,
    char *buf)

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