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[v2,09/13] media: cx24116: prevent overflows on SNR calculus

Message ID b7e7f344d57ce1dd8c1bb0f82abfc8e5967eaec4.1729230718.git.mchehab+huawei@kernel.org
State Accepted
Commit 576a307a7650bd544fbb24df801b9b7863b85e2f
Headers show
Series Media: fix several issues on drivers | expand

Commit Message

Mauro Carvalho Chehab Oct. 18, 2024, 5:53 a.m. UTC 
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>
---
 drivers/media/dvb-frontends/cx24116.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
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Patch

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;