From: "Michael Büsch" <m@bues.ch>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Larry Finger <Larry.Finger@lwfinger.net>,
Kalle Valo <kvalo@codeaurora.org>,
linux-wireless@vger.kernel.org, b43-dev@lists.infradead.org,
kernel-janitors@vger.kernel.org
Subject: Re: [PATCH 1/2] b43legacy: fix a lower bounds test
Date: Wed, 6 Oct 2021 18:13:58 +0200 [thread overview]
Message-ID: <20211006181358.67a23e18@wiggum> (raw)
In-Reply-To: <20211006073542.GD8404@kili>
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On Wed, 6 Oct 2021 10:35:42 +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: 75388acd0cd8 ("[B43LEGACY]: add mac80211-based driver for legacy BCM43xx devices")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> This fix is correct, but making dead code go live can sometimes expose
> bugs which were previously hiding and is always carries a slight risk.
>
> drivers/net/wireless/broadcom/b43legacy/radio.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/broadcom/b43legacy/radio.c b/drivers/net/wireless/broadcom/b43legacy/radio.c
> index 06891b4f837b..fdf78c10a05c 100644
> --- a/drivers/net/wireless/broadcom/b43legacy/radio.c
> +++ b/drivers/net/wireless/broadcom/b43legacy/radio.c
> @@ -283,7 +283,7 @@ u8 b43legacy_radio_aci_scan(struct b43legacy_wldev *dev)
> & 0x7FFF);
> b43legacy_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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next prev parent reply other threads:[~2021-10-06 16:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-06 7:35 [PATCH 1/2] b43legacy: fix a lower bounds test Dan Carpenter
2021-10-06 7:36 ` [PATCH 2/2] b43: " Dan Carpenter
2021-10-06 16:13 ` Michael Büsch
2021-10-06 16:13 ` Michael Büsch [this message]
2021-10-11 6:09 ` [PATCH 1/2] b43legacy: " Kalle Valo
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