Re: [PATCH 2/2] b43: fix a lower bounds test

From: "Michael Büsch" <m@bues.ch>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Kalle Valo <kvalo@codeaurora.org>,
	kernel-janitors@vger.kernel.org, linux-wireless@vger.kernel.org,
	b43-dev@lists.infradead.org
Subject: Re: [PATCH 2/2] b43: fix a lower bounds test
Date: Wed, 6 Oct 2021 18:13:34 +0200	[thread overview]
Message-ID: <20211006181334.621ac10c@wiggum> (raw)
In-Reply-To: <20211006073621.GE8404@kili>

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On Wed, 6 Oct 2021 10:36:22 +0300
Dan Carpenter <dan.carpenter@oracle.com> wrote:

> The problem is that "channel" is an unsigned int, when it's less 5 the
> value of "channel - 5" is not a negative number as one would expect but
> is very high positive value instead.
> 
> This means that "start" becomes a very high positive value.  The result
> of that is that we never enter the "for (i = start; i <= end; i++) {"
> loop.  Instead of storing the result from b43legacy_radio_aci_detect()
> it just uses zero.
> 
> Fixes: ef1a628d83fc ("b43: Implement dynamic PHY API")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>  drivers/net/wireless/broadcom/b43/phy_g.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/broadcom/b43/phy_g.c b/drivers/net/wireless/broadcom/b43/phy_g.c
> index d5a1a5c58236..ac72ca39e409 100644
> --- a/drivers/net/wireless/broadcom/b43/phy_g.c
> +++ b/drivers/net/wireless/broadcom/b43/phy_g.c
> @@ -2297,7 +2297,7 @@ static u8 b43_gphy_aci_scan(struct b43_wldev *dev)
>  	b43_phy_mask(dev, B43_PHY_G_CRS, 0x7FFF);
>  	b43_set_all_gains(dev, 3, 8, 1);
>  
> -	start = (channel - 5 > 0) ? channel - 5 : 1;
> +	start = (channel > 5) ? channel - 5 : 1;
>  	end = (channel + 5 < 14) ? channel + 5 : 13;
>  
>  	for (i = start; i <= end; i++) {

Nice finding.

Acked-by: Michael Büsch <m@bues.ch>

-- 
Michael

https://bues.ch/

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