Re: [PATCH] mac80211: Fix oops in OCB mode when receiving data when not joined

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2015-08-05 at 15:38 +0200, Bertold Van den Bergh wrote:
> The current implementation in ocb.c can cause a kernel oops when the
> interface is up, but no ocb has been joined. When data is received
> with the broadcast BSSID rx_no_sta is called. This function uses
> uninitialized variables because the join function has not yet been 
> used.
> 
> Signed-off-by: Bertold Van den Bergh <
> bertold.vandenbergh@esat.kuleuven.be>
> ---
>  net/mac80211/ocb.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/net/mac80211/ocb.c b/net/mac80211/ocb.c
> index 573b81a..5da2bd3 100644
> --- a/net/mac80211/ocb.c
> +++ b/net/mac80211/ocb.c
> @@ -50,6 +50,9 @@ void ieee80211_ocb_rx_no_sta(struct 
> ieee80211_sub_if_data *sdata,
>  	struct sta_info *sta;
>  	int band;
>  
> +	if (!ifocb->joined)
> +		return;
> 
Wouldn't it make more sense to put this check into
ieee80211_accept_frame() and, in addition to not doing any station
processing, simply dropping the frame completely? Like such:

--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -3314,6 +3314,8 @@ static bool ieee80211_accept_frame(struct ieee80211_rx_data *rx)
 		}
 		return true;
 	case NL80211_IFTYPE_OCB:
+		if (!sdata->u.ocb.joined)
+			return false;
 		if (!bssid)
 			return false;
 		if (ieee80211_is_beacon(hdr->frame_control))

johannes