On 10/03/2012 12:25 PM, Hans-Frieder Vogt wrote:
As spotted by Dan Carpenter <dan.carpenter@xxxxxxxxxx> (thanks!), we have
improperly used an unsigned variable in a calculation that may result in a
negative number. This may cause an unintended underflow if the interface
frequency of the tuner is > approx. 40MHz.
This patch should resolve the issue, following an approach similar to what is
used in af9013.c.
Signed-off-by: Hans-Frieder Vogt <hfvogt@xxxxxxx>
Acked-by: Antti Palosaari <crope@xxxxxx>
I will PULL-request that via my tree for 3.7. I don't see any reason
this should go older ones.
regards
Antti
drivers/media/dvb-frontends/af9033.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
--- a/drivers/media/dvb-frontends/af9033.c 2012-09-28 05:45:17.000000000 +0200
+++ b/drivers/media/dvb-frontends/af9033.c 2012-10-03 11:08:18.160894181 +0200
@@ -408,7 +408,7 @@ static int af9033_set_frontend(struct dv
{
struct af9033_state *state = fe->demodulator_priv;
struct dtv_frontend_properties *c = &fe->dtv_property_cache;
- int ret, i, spec_inv;
+ int ret, i, spec_inv, sampling_freq;
u8 tmp, buf[3], bandwidth_reg_val;
u32 if_frequency, freq_cw, adc_freq;
@@ -465,18 +465,20 @@ static int af9033_set_frontend(struct dv
else
if_frequency = 0;
- while (if_frequency > (adc_freq / 2))
- if_frequency -= adc_freq;
+ sampling_freq = if_frequency;
- if (if_frequency >= 0)
+ while (sampling_freq > (adc_freq / 2))
+ sampling_freq -= adc_freq;
+
+ if (sampling_freq >= 0)
spec_inv *= -1;
else
- if_frequency *= -1;
+ sampling_freq *= -1;
- freq_cw = af9033_div(state, if_frequency, adc_freq, 23ul);
+ freq_cw = af9033_div(state, sampling_freq, adc_freq, 23ul);
if (spec_inv == -1)
- freq_cw *= -1;
+ freq_cw = 0x800000 - freq_cw;
/* get adc multiplies */
ret = af9033_rd_reg(state, 0x800045, &tmp);
Hans-Frieder Vogt e-mail: hfvogt <at> gmx .dot. net
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