linux-kernel - [PATCH] media: dib7000p: Fix potential division by zero

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Message-ID: <20230324131209.651475-1-d.dulov@aladdin.ru>
Date:   Fri, 24 Mar 2023 06:12:09 -0700
From:   Daniil Dulov <d.dulov@...ddin.ru>
To:     Andrew Lunn <andrew@...n.ch>
CC:     Daniil Dulov <d.dulov@...ddin.ru>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Kurt Kanzenbach <kurt@...utronix.de>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <lvc-patches@...uxtesting.org>
Subject: [PATCH] media: dib7000p: Fix potential division by zero

Variable loopdiv can be assigned 0, then it is used as a denominator,
without checking it for 0.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 713d54a8bd81 ("[media] DiB7090: add support for the dib7090 based")
Signed-off-by: Daniil Dulov <d.dulov@...ddin.ru>
---
 drivers/media/dvb-frontends/dib7000p.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/dvb-frontends/dib7000p.c b/drivers/media/dvb-frontends/dib7000p.c
index 55bee50aa871..bea5717907e7 100644
--- a/drivers/media/dvb-frontends/dib7000p.c
+++ b/drivers/media/dvb-frontends/dib7000p.c
@@ -497,7 +497,7 @@ static int dib7000p_update_pll(struct dvb_frontend *fe, struct dibx000_bandwidth
 	prediv = reg_1856 & 0x3f;
 	loopdiv = (reg_1856 >> 6) & 0x3f;
 
-	if ((bw != NULL) && (bw->pll_prediv != prediv || bw->pll_ratio != loopdiv)) {
+	if (loopdiv && (bw != NULL) && (bw->pll_prediv != prediv || bw->pll_ratio != loopdiv)) {
 		dprintk("Updating pll (prediv: old =  %d new = %d ; loopdiv : old = %d new = %d)\n", prediv, bw->pll_prediv, loopdiv, bw->pll_ratio);
 		reg_1856 &= 0xf000;
 		reg_1857 = dib7000p_read_word(state, 1857);
-- 
2.25.1