[PATCH AUTOSEL 4.9 17/23] cfg80211: fix a type issue in ieee80211_chandef_to_operating_class()

From: Sasha Levin <Alexander.Levin@microsoft.com>
To: "stable@vger.kernel.org" <stable@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>,
	Johannes Berg <johannes.berg@intel.com>,
	Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL 4.9 17/23] cfg80211: fix a type issue in ieee80211_chandef_to_operating_class()
Date: Mon, 24 Sep 2018 14:49:33 +0000	[thread overview]
Message-ID: <20180924144919.164617-17-alexander.levin@microsoft.com> (raw)
In-Reply-To: <20180924144919.164617-1-alexander.levin@microsoft.com>

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit 8442938c3a2177ba16043b3a935f2c78266ad399 ]

The "chandef->center_freq1" variable is a u32 but "freq" is a u16 so we
are truncating away the high bits.  I noticed this bug because in commit
9cf0a0b4b64a ("cfg80211: Add support for 60GHz band channels 5 and 6")
we made "freq <= 56160 + 2160 * 6" a valid requency when before it was
only "freq <= 56160 + 2160 * 4" that was valid.  It introduces a static
checker warning:

    net/wireless/util.c:1571 ieee80211_chandef_to_operating_class()
    warn: always true condition '(freq <= 56160 + 2160 * 6) => (0-u16max <= 69120)'

But really we probably shouldn't have been truncating the high bits
away to begin with.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 net/wireless/util.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/wireless/util.c b/net/wireless/util.c
index bb54d9db82df..3b9a81998014 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1432,7 +1432,7 @@ bool ieee80211_chandef_to_operating_class(struct cfg80211_chan_def *chandef,
 					  u8 *op_class)
 {
 	u8 vht_opclass;
-	u16 freq = chandef->center_freq1;
+	u32 freq = chandef->center_freq1;
 
 	if (freq >= 2412 && freq <= 2472) {
 		if (chandef->width > NL80211_CHAN_WIDTH_40)
-- 
2.17.1
