netdev - Re: [PATCH] media: dib7000p: Fix potential division by zero

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Message-ID: <20230324131445.g42kvq5wzj2z3qil@skbuf>
Date:   Fri, 24 Mar 2023 15:14:45 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     Daniil Dulov <d.dulov@...ddin.ru>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...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: Re: [PATCH] media: dib7000p: Fix potential division by zero

Hi Daniil,

On Fri, Mar 24, 2023 at 06:12:09AM -0700, Daniil Dulov wrote:
> 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
> 

Did you send this patch to the correct recipients and mailing lists?

$ ./scripts/get_maintainer.pl drivers/media/dvb-frontends/dib7000p.c
Mauro Carvalho Chehab <mchehab@...nel.org> (maintainer:MEDIA INPUT INFRASTRUCTURE (V4L/DVB))
linux-media@...r.kernel.org (open list:MEDIA INPUT INFRASTRUCTURE (V4L/DVB))
linux-kernel@...r.kernel.org (open list)