From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from promwad.com ([83.149.69.23]:33483 "EHLO promwad.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751509AbZF1MSa (ORCPT ); Sun, 28 Jun 2009 08:18:30 -0400 Message-ID: <4A475F82.9040007@promwad.com> Date: Sun, 28 Jun 2009 15:18:10 +0300 From: Ivan Kuten Reply-To: ivan.kuten@promwad.com MIME-Version: 1.0 To: linux-wireless@vger.kernel.org CC: Johannes Berg , Yauhen Kharuzhy Subject: Re: [PATCH] wireless: Compare ethernet addresses by unaligned safe way References: <1245149672-18063-1-git-send-email-yauhen.kharuzhy@promwad.com> <1245150895.8623.3.camel@johannes.local> In-Reply-To: <1245150895.8623.3.camel@johannes.local> Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: Hello, In net/wireless/scan.c : cfg80211_wext_siwscan there seems also unaligned allocations for creq->ssids and creq->channels. Should it be something like that? Modified: trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c ============================================================================== --- trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c (original) +++ trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c Fri Jun 26 14:00:52 2009 @@ -619,7 +619,7 @@ if (wiphy->bands[band]) n_channels += wiphy->bands[band]->n_channels; - creq = kzalloc(sizeof(*creq) + sizeof(struct cfg80211_ssid) + + creq = kzalloc(roundup(sizeof(*creq), 4) + roundup(sizeof(struct cfg80211_ssid), 4) + n_channels * sizeof(void *), GFP_ATOMIC); if (!creq) { @@ -629,8 +629,8 @@ creq->wiphy = wiphy; creq->ifidx = dev->ifindex; - creq->ssids = (void *)(creq + 1); - creq->channels = (void *)(creq->ssids + 1); + creq->ssids = (void *)creq + roundup(sizeof(*creq), 4); + creq->channels = (void *)creq->ssids + roundup(sizeof(*creq->ssids), 4); creq->n_channels = n_channels; creq->n_ssids = 1; Regards, Ivan > On Tue, 2009-06-16 at 13:54 +0300, Yauhen Kharuzhy wrote: >> When we try to run RTL8187 driver on AD BlackFin platform, we got >> messages from kernel about unaligned memory access at >> compare_ether_addr() calls. >> >> Replacing of compare_ether_addr() by memcmp() fixes this problem. > > This shouldn't be necessary. Which operand is unaligned? > >> --- a/net/mac80211/ibss.c >> +++ b/net/mac80211/ibss.c >> @@ -395,7 +395,7 @@ struct sta_info *ieee80211_ibss_add_sta(struct ieee80211_sub_if_data *sdata, >> return NULL; >> } >> >> - if (compare_ether_addr(bssid, sdata->u.ibss.bssid)) >> + if (memcmp(bssid, sdata->u.ibss.bssid, ETH_ALEN)) >> return NULL; > > So in this case it seems that it is possible that u.ibss.bssid is not > aligned, consider fixing by doing > > --- ieee80211_i.h > +++ ieee80211_i.h > - u8 bssid[ETH_ALEN]; > + u8 bssid[ETH_ALEN] __align(2); > > or so instead. > >> --- a/net/wireless/scan.c >> +++ b/net/wireless/scan.c >> @@ -134,7 +134,7 @@ static bool is_bss(struct cfg80211_bss *a, >> { >> const u8 *ssidie; >> >> - if (bssid && compare_ether_addr(a->bssid, bssid)) >> + if (bssid && memcmp(a->bssid, bssid, ETH_ALEN)) > > Since a->bssid is after a pointer I can't see how it would be unaligned, > and bssid should be unaligned only if the call trace shows it's coming > from the above u.ibss.bssid. > > johannes