linux-kernel - [PATCH AUTOSEL 4.18 58/76] cfg80211: fix a type issue in ieee80211_chandef_to_operating

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Date:   Mon, 24 Sep 2018 14:48:36 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Dan Carpenter <dan.carpenter@...cle.com>,
        Johannes Berg <johannes.berg@...el.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL 4.18 58/76] cfg80211: fix a type issue in
 ieee80211_chandef_to_operating_class()

From: Dan Carpenter <dan.carpenter@...cle.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@...cle.com>
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.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 3c654cd7ba56..908bf5b6d89e 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1374,7 +1374,7 @@ 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