Return-path: Received: from mail-wi0-f169.google.com ([209.85.212.169]:43207 "EHLO mail-wi0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752959AbaJMKYc (ORCPT ); Mon, 13 Oct 2014 06:24:32 -0400 Date: Mon, 13 Oct 2014 12:24:19 +0200 From: Karl Beldan To: stable@vger.kernel.org Cc: Johannes Berg , linux-wireless , Karl Beldan Subject: Re: [PATCH] mac80211: fix typo in starting baserate for rts_cts_rate_idx Message-ID: <20141013102419.GA31608@magnum.frso.rivierawaves.com> (sfid-20141013_122436_435395_79C64183) References: <1413193692-30521-1-git-send-email-karl.beldan@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 In-Reply-To: <1413193692-30521-1-git-send-email-karl.beldan@gmail.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: Properly cc'ing stable (I used kernel.org instead of vger.kernel.org). On Mon, Oct 13, 2014 at 11:48:12AM +0200, Karl Beldan wrote: > 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 >