Return-path: Received: from mail.candelatech.com ([208.74.158.172]:40258 "EHLO ns3.lanforge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932335AbaDVSDw (ORCPT ); Tue, 22 Apr 2014 14:03:52 -0400 Message-ID: <5356AEF0.1000208@candelatech.com> (sfid-20140422_200406_426272_5C64EF46) Date: Tue, 22 Apr 2014 11:03:28 -0700 From: Ben Greear MIME-Version: 1.0 To: "John W. Linville" CC: Felix Fietkau , ath9k-devel@venema.h4ckr.net, 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> <534F870E.80209@openwrt.org> <20140422175322.GA16193@tuxdriver.com> In-Reply-To: <20140422175322.GA16193@tuxdriver.com> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 04/22/2014 10:53 AM, John W. Linville wrote: > Please consider Felix's comments while refactoring this for the > current code structure... I'm low on time, but will resend a patch when I get a chance. If someone else wants to send in the updated patch that is fine by me. Thanks, Ben > > John > > On Thu, Apr 17, 2014 at 09:47:26AM +0200, Felix Fietkau wrote: >> 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)) { >>> >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-wireless" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > -- Ben Greear Candela Technologies Inc http://www.candelatech.com