Return-path: Received: from mail-wi0-f175.google.com ([209.85.212.175]:55096 "EHLO mail-wi0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752903AbaJMJsl (ORCPT ); Mon, 13 Oct 2014 05:48:41 -0400 Received: by mail-wi0-f175.google.com with SMTP id d1so6853292wiv.8 for ; Mon, 13 Oct 2014 02:48:40 -0700 (PDT) From: Karl Beldan To: Johannes Berg Cc: linux-wireless , Karl Beldan , Karl Beldan , stable@kernel.org Subject: [PATCH] mac80211: fix typo in starting baserate for rts_cts_rate_idx Date: Mon, 13 Oct 2014 11:48:12 +0200 Message-Id: <1413193692-30521-1-git-send-email-karl.beldan@gmail.com> (sfid-20141013_114845_989649_09FF01C5) Sender: linux-wireless-owner@vger.kernel.org List-ID: From: Karl Beldan It affects non-(V)HT rates and can lead to selecting an rts_cts rate that is not a basic rate or way superior to the reference rate (ATM rates[0] used for the 1st attempt of the protected frame data). E.g, assuming drivers register growing (bitrate) sorted tables of ieee80211_rate-s, having : - rates[0].idx == d'2 and basic_rates == b'10100 will select rts_cts idx b'10011 & ~d'(BIT(2)-1), i.e. 1, likewise - rates[0].idx == d'2 and basic_rates == b'10001 will select rts_cts idx b'10000 The first is not a basic rate and the second is > rates[0]. Also, wrt severity of the addressed misbehavior, ATM we only have one rts_cts_rate_idx rather than one per rate table entry, so this idx might still point to bitrates > rates[1..MAX_RATES]. Fixes: 5253ffb8 ("mac80211: always pick a basic rate to tx RTS/CTS for pre-HT rates") Signed-off-by: Karl Beldan --- net/mac80211/rate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/mac80211/rate.c b/net/mac80211/rate.c index 8fdadfd..6081329 100644 --- a/net/mac80211/rate.c +++ b/net/mac80211/rate.c @@ -448,7 +448,7 @@ static void rate_fixup_ratelist(struct ieee80211_vif *vif, */ if (!(rates[0].flags & IEEE80211_TX_RC_MCS)) { u32 basic_rates = vif->bss_conf.basic_rates; - s8 baserate = basic_rates ? ffs(basic_rates - 1) : 0; + s8 baserate = basic_rates ? ffs(basic_rates) - 1 : 0; rate = &sband->bitrates[rates[0].idx]; -- 2.0.1