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| author |   Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2017-11-01 17:06:03 -0400 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2017-12-11 13:04:54 -0500 |
| commit | f303810cf189144a613a7efa991816655e6467ea (patch) | |
| tree | 52e5f65350e6dbfa322979b7b8e6f0ef6e390136 | |
| parent | media: mb86a16: be more resilient if I2C fails on sync (diff) | |
| download | linux-dev-f303810cf189144a613a7efa991816655e6467ea.tar.xz linux-dev-f303810cf189144a613a7efa991816655e6467ea.zip | |
media: mb86a16: avoid division by zero
As warned by smatch:
drivers/media/dvb-frontends/mb86a16.c:1690 mb86a16_read_ber() error: uninitialized symbol 'timer'.
drivers/media/dvb-frontends/mb86a16.c:1706 mb86a16_read_ber() error: uninitialized symbol 'timer'.
There is a potential risk of doing a division by zero if
timer is not handled well. Enforce it by setting a bit mask
for the values used to select the timer.
It should be noticed that I don't have mb86a16 datasheet. So,
the bitmask was guessed based on the existing checks for
the field. At worse case scenario, it will just show a
badly calculated bit error rate, but it won't crash.
While here, optimize the logic to prevent uneeded tests.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
| -rw-r--r-- | drivers/media/dvb-frontends/mb86a16.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/drivers/media/dvb-frontends/mb86a16.c b/drivers/media/dvb-frontends/mb86a16.c index f1aad52094c3..5d2bb76bc07a 100644 --- a/drivers/media/dvb-frontends/mb86a16.c +++ b/drivers/media/dvb-frontends/mb86a16.c @@ -1677,15 +1677,15 @@ static int mb86a16_read_ber(struct dvb_frontend *fe, u32 *ber) * the deinterleaver output. * monitored BER is expressed as a 20 bit output in total */ - ber_rst = ber_mon >> 3; + ber_rst = (ber_mon >> 3) & 0x03; *ber = (((ber_msb << 8) | ber_mid) << 8) | ber_lsb; if (ber_rst == 0) timer = 12500000; - if (ber_rst == 1) + else if (ber_rst == 1) timer = 25000000; - if (ber_rst == 2) + else if (ber_rst == 2) timer = 50000000; - if (ber_rst == 3) + else /* ber_rst == 3 */ timer = 100000000; *ber /= timer; @@ -1697,11 +1697,11 @@ static int mb86a16_read_ber(struct dvb_frontend *fe, u32 *ber) * QPSK demodulator output. * monitored BER is expressed as a 24 bit output in total */ - ber_tim = ber_mon >> 1; + ber_tim = (ber_mon >> 1) & 0x01; *ber = (((ber_msb << 8) | ber_mid) << 8) | ber_lsb; if (ber_tim == 0) timer = 16; - if (ber_tim == 1) + else /* ber_tim == 1 */ timer = 24; *ber /= 2 ^ timer; |