[media] m88ts2022: fix 32bit overflow on filter calc

Maximum satellite symbol rate used is 45000000Sps which overflows
when multiplied by 135. As final calculation result is fraction,
we could use mult_frac macro in order to keep calculation inside
32 bit number limits and prevent overflow.

Original bug and fix was provided by Nibble Max. I decided to
implement it differently as it is now.

Reported-by: Nibble Max <nibble.max@gmail.com>
Tested-by: Nibble Max <nibble.max@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

diff --git a/drivers/media/tuners/m88ts2022.c b/drivers/media/tuners/m88ts2022.c
index 40c42dec721b9de556dacc6cadc12a80ba3cc06b..7a62097aa9eafa89aee2f0e8f5d894c592c13bdb 100644 (file)
--- a/drivers/media/tuners/m88ts2022.c
+++ b/drivers/media/tuners/m88ts2022.c
@@ -314,7 +314,7 @@ static int m88ts2022_set_params(struct dvb_frontend *fe)
        div_min = gdiv28 * 78 / 100;
        div_max = clamp_val(div_max, 0U, 63U);
 
-       f_3db_hz = c->symbol_rate * 135UL / 200UL;
+       f_3db_hz = mult_frac(c->symbol_rate, 135, 200);
        f_3db_hz +=  2000000U + (frequency_offset_khz * 1000U);
        f_3db_hz = clamp(f_3db_hz, 7000000U, 40000000U);