V4L/DVB (13107): tda18271: fix overflow in FM radio frequency calculation

commit 4d8317876d5f53ef792e90f89d8f162d7bca5c81 upstream.

Multiplication by 62500 causes an overflow in the 32 bit freq variable,
which is later divided by 1000 when using FM radio.

This patch prevents the overflow by scaling the frequency value correctly
upfront.  Thanks to Henk Vergonet for spotting the problem and providing
a preliminary patch, which this changeset was based upon.

Cc: Henk Vergonet <Henk.Vergonet@gmail.com>
Signed-off-by: Michael Krufky <mkrufky@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/media/common/tuners/tda18271-fe.c b/drivers/media/common/tuners/tda18271-fe.c
index 93063c6fbbf634e42aac29b3502de2b66104e232..ac77b8da935f3236d1e68d68bcbdeec666cc2447 100644 (file)
--- a/drivers/media/common/tuners/tda18271-fe.c
+++ b/drivers/media/common/tuners/tda18271-fe.c
@@ -927,12 +927,12 @@ static int tda18271_set_analog_params(struct dvb_frontend *fe,
        struct tda18271_std_map_item *map;
        char *mode;
        int ret;
-       u32 freq = params->frequency * 62500;
+       u32 freq = params->frequency * 125 *
+               ((params->mode == V4L2_TUNER_RADIO) ? 1 : 1000) / 2;
 
        priv->mode = TDA18271_ANALOG;
 
        if (params->mode == V4L2_TUNER_RADIO) {
-               freq = freq / 1000;
                map = &std_map->fm_radio;
                mode = "fm";
        } else if (params->std & V4L2_STD_MN) {