Return-path: Received: from py-out-1112.google.com ([64.233.166.176]:35314 "EHLO py-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753913AbYETMyZ (ORCPT ); Tue, 20 May 2008 08:54:25 -0400 Received: by py-out-1112.google.com with SMTP id u52so2404947pyb.10 for ; Tue, 20 May 2008 05:54:25 -0700 (PDT) Message-ID: <1ba2fa240805200554w9354d14v9abc70f676540b9b@mail.gmail.com> (sfid-20080520_145429_436059_08A7992C) Date: Tue, 20 May 2008 15:54:24 +0300 From: "Tomas Winkler" To: "Helmut Schaa" Subject: Re: [PATCHv5] mac80211: fix NULL pointer dereference in ieee80211_compatible_rates Cc: "John Linville" , "Johannes Berg" , "Larry Finger" , linux-wireless@vger.kernel.org In-Reply-To: <20080520095637.2cq5p5ohhc8440o4@imap.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 References: <20080520095637.2cq5p5ohhc8440o4@imap.suse.de> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Tue, May 20, 2008 at 10:56 AM, Helmut Schaa wrote: > Fix a possible NULL pointer dereference in ieee80211_compatible_rates > introduced in the patch "mac80211: fix association with some APs". If no bss > is available just use all supported rates in the association request. > > Signed-off-by: Helmut Schaa > --- > > diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c > index 76ad4ed..3f7f92a 100644 > --- a/net/mac80211/mlme.c > +++ b/net/mac80211/mlme.c > @@ -721,7 +721,17 @@ static void ieee80211_send_assoc(struct net_device > *dev, > capab |= WLAN_CAPABILITY_PRIVACY; > if (bss->wmm_ie) > wmm = 1; > + > + /* get all rates supported by the device and the AP as > + * some APs don't like getting a superset of their rates > + * in the association request (e.g. D-Link DAP 1353 in > + * b-only mode) */ > + rates_len = ieee80211_compatible_rates(bss, sband, &rates); > + > ieee80211_rx_bss_put(dev, bss); > + } else { > + rates = ~0; > + rates_len = sband->n_bitrates; > } > > mgmt = (struct ieee80211_mgmt *) skb_put(skb, 24); > @@ -752,10 +762,7 @@ static void ieee80211_send_assoc(struct net_device > *dev, > *pos++ = ifsta->ssid_len; > memcpy(pos, ifsta->ssid, ifsta->ssid_len); > > - /* all supported rates should be added here but some APs > - * (e.g. D-Link DAP 1353 in b-only mode) don't like that > - * Therefore only add rates the AP supports */ > - rates_len = ieee80211_compatible_rates(bss, sband, &rates); > + /* add all rates which were marked to be used above */ > supp_rates_len = rates_len; > if (supp_rates_len > 8) > supp_rates_len = 8; > > I found one ieee80211_rx_bss_{get,put} imbalance in ieee80211_sta_join_ibss function That may cause this problem yet it doesn't look like this is the case. ieee80211_sta_join_ibss calls ieee80211_rx_bss_put on 'bss' that it receives as an argument Keep searching. I suggest to insert at least some WARN_ON(1) for the else case. Tomas