[PATCH 5.1 062/138] cfg80211: util: fix bit count off by one

[Greg Kroah-Hartman]

[ Upstream commit 1a473d6092d5d182914bea854ce0b21e6d12519d ]

The bits of Rx MCS Map in VHT capability were enumerated
with index transform - index i -> (i + 1) bit => nss i. BUG!
while it should be -   index i -> (i + 1) bit => (i + 1) nss.

The bug was exposed in commit a53b2a0b1245 ("iwlwifi: mvm: implement VHT
extended NSS support in rs.c"), where iwlwifi started using the
function.

Signed-off-by: Mordechay Goodstein <mordechay.goodstein@xxxxxxxxx>
Fixes: b0aa75f0b1b2 ("ieee80211: add new VHT capability fields/parsing")
Signed-off-by: Luca Coelho <luciano.coelho@xxxxxxxxx>
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 5a03f38788e7..5ac66a571e33 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1989,7 +1989,7 @@ int ieee80211_get_vht_max_nss(struct ieee80211_vht_cap *cap,
 			continue;
 
 		if (supp >= mcs_encoding) {
-			max_vht_nss = i;
+			max_vht_nss = i + 1;
 			break;
 		}
 	}
-- 
2.20.1