On Tue, May 20, 2008 at 10:56 AM, Helmut Schaa <hschaa@xxxxxxx> 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 <hschaa@xxxxxxx>
> ---
>
> 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
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