If reading SNR registers fail, a negative number will be returned, causing an underflow when reading SNR registers.
Prevent that.
Fixes: 8953db793d5b ("V4L/DVB (9178): cx24116: Add module parameter to return SNR as ESNO.") Cc: stable@vger.kernel.org Signed-off-by: Mauro Carvalho Chehab mchehab+huawei@kernel.org --- drivers/media/dvb-frontends/cx24116.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/media/dvb-frontends/cx24116.c b/drivers/media/dvb-frontends/cx24116.c index 8b978a9f74a4..f5dd3a81725a 100644 --- a/drivers/media/dvb-frontends/cx24116.c +++ b/drivers/media/dvb-frontends/cx24116.c @@ -741,6 +741,7 @@ static int cx24116_read_snr_pct(struct dvb_frontend *fe, u16 *snr) { struct cx24116_state *state = fe->demodulator_priv; u8 snr_reading; + int ret; static const u32 snr_tab[] = { /* 10 x Table (rounded up) */ 0x00000, 0x0199A, 0x03333, 0x04ccD, 0x06667, 0x08000, 0x0999A, 0x0b333, 0x0cccD, 0x0e667, @@ -749,7 +750,11 @@ static int cx24116_read_snr_pct(struct dvb_frontend *fe, u16 *snr)
dprintk("%s()\n", __func__);
- snr_reading = cx24116_readreg(state, CX24116_REG_QUALITY0); + ret = cx24116_readreg(state, CX24116_REG_QUALITY0); + if (ret < 0) + return ret; + + snr_reading = ret;
if (snr_reading >= 0xa0 /* 100% */) *snr = 0xffff;