iio: dac: ad5686: fix input raw value check

Fix range check for input raw value, which is off by one, i.e., for a
10-bit DAC the max valid value is 1023, but 1 << 10 equals 1024, which
passes the previous check, allowing an out-of-range write. The issue
exists since the ad5686 driver was first introduced.

Fixes: c2f37c8dcadc ("iio: dac: New driver for AD5686R, AD5685R, AD5684R Digital to analog converters")
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Rodrigo Alencar <rodrigo.alencar@analog.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/dac/ad5686.c b/drivers/iio/dac/ad5686.c
index b85d5c5a864bbe69da8a33381796673a0a0e5c66..27878a6318ffcf421a148efd346b256897fc5330 100644 (file)
--- a/drivers/iio/dac/ad5686.c
+++ b/drivers/iio/dac/ad5686.c
@@ -154,7 +154,7 @@ static int ad5686_write_raw(struct iio_dev *indio_dev,
 
        switch (mask) {
        case IIO_CHAN_INFO_RAW:
-               if (val > (1 << chan->scan_type.realbits) || val < 0)
+               if (val >= (1 << chan->scan_type.realbits) || val < 0)
                        return -EINVAL;
 
                mutex_lock(&st->lock);