[PATCH 1/2] b43legacy: fix a lower bounds test

From: Dan Carpenter <dan.carpenter@oracle.com>
To: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Kalle Valo <kvalo@codeaurora.org>,
	linux-wireless@vger.kernel.org, b43-dev@lists.infradead.org,
	kernel-janitors@vger.kernel.org
Subject: [PATCH 1/2] b43legacy: fix a lower bounds test
Date: Wed, 6 Oct 2021 10:35:42 +0300	[thread overview]
Message-ID: <20211006073542.GD8404@kili> (raw)

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++) {
-- 
2.20.1

