media: cx24116: prevent overflows on SNR calculus

commit 576a307a7650bd544fbb24df801b9b7863b85e2f upstream.

as reported by Coverity, 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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mauro Carvalho Chehab 2024-10-15 12:14:11 +02:00 committed by Kreciorek
parent 15ecef70ed
commit fd73218ffe

View file

@ -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;