Return-path: Received: from nbd.name ([46.4.11.11]:41959 "EHLO nbd.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752059AbaDQHrn (ORCPT ); Thu, 17 Apr 2014 03:47:43 -0400 Message-ID: <534F870E.80209@openwrt.org> (sfid-20140417_094813_160454_28641621) Date: Thu, 17 Apr 2014 09:47:26 +0200 From: Felix Fietkau MIME-Version: 1.0 To: greearb@candelatech.com, ath9k-devel@venema.h4ckr.net CC: linux-wireless@vger.kernel.org Subject: Re: [PATCH] ath9k: Prevent divide by zero kernel crash. References: <1397695240-13710-1-git-send-email-greearb@candelatech.com> In-Reply-To: <1397695240-13710-1-git-send-email-greearb@candelatech.com> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 2014-04-17 02:40, greearb@candelatech.com wrote: > From: Ben Greear > > Make sure we cannot ever assign beacon interval to zero. > > Signed-off-by: Ben Greear > --- > drivers/net/wireless/ath/ath9k/beacon.c | 4 ++++ > drivers/net/wireless/ath/ath9k/recv.c | 3 ++- > 2 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/wireless/ath/ath9k/beacon.c b/drivers/net/wireless/ath/ath9k/beacon.c > index 2e8bba0..5391f01 100644 > --- a/drivers/net/wireless/ath/ath9k/beacon.c > +++ b/drivers/net/wireless/ath/ath9k/beacon.c > @@ -443,6 +443,8 @@ static u32 ath9k_mod_tsf64_tu(u64 tsf, u32 div_tu) > { > u32 tsf_mod, tsf_hi, tsf_lo, mod_hi, mod_lo; > > + if (WARN_ON_ONCE(div_tu == 0)) > + div_tu = 100; > tsf_mod = tsf & (BIT(10) - 1); > tsf_hi = tsf >> 32; > tsf_lo = ((u32) tsf) >> 10; Why add this warning here if you already have the additions below? We don't need multiple layers of defensive checks for the same thing. > @@ -667,6 +669,8 @@ static void ath9k_cache_beacon_config(struct ath_softc *sc, > "Caching beacon data for BSS: %pM\n", bss_conf->bssid); > > cur_conf->beacon_interval = bss_conf->beacon_int; > + if (WARN_ON_ONCE(cur_conf->beacon_interval == 0)) > + cur_conf->beacon_interval = 100; > cur_conf->dtim_period = bss_conf->dtim_period; > cur_conf->listen_interval = 1; > cur_conf->dtim_count = 1; > diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c > index b97217d..79c20c7 100644 > --- a/drivers/net/wireless/ath/ath9k/recv.c > +++ b/drivers/net/wireless/ath/ath9k/recv.c > @@ -538,7 +538,8 @@ static void ath_rx_ps_beacon(struct ath_softc *sc, struct sk_buff *skb) > sc->ps_flags &= ~PS_BEACON_SYNC; > ath_dbg(common, PS, > "Reconfigure beacon timers based on synchronized timestamp\n"); > - ath9k_set_beacon(sc); > + if (!(WARN_ON_ONCE(sc->cur_beacon_conf.beacon_interval == 0))) > + ath9k_set_beacon(sc); > } > > if (ath_beacon_dtim_pending_cab(skb)) { >