mac80211: avoid crashing when no scan sdata

Using the scan_sdata variable here is terribly wrong,
if there has never been a scan then we fail. However,
we need a bandaid...

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: stable@kernel.org [2.6.29]
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 1b14d0204dd2..dc60804d6dd0 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -2113,12 +2113,13 @@ void ieee80211_dynamic_ps_enable_work(struct work_struct *work)
         struct ieee80211_local *local =
                 container_of(work, struct ieee80211_local,
                              dynamic_ps_enable_work);
+        /* XXX: using scan_sdata is completely broken! */
         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 
         if (local->hw.conf.flags & IEEE80211_CONF_PS)
                 return;
 
-        if (local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK)
+        if (local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK && sdata)
                 ieee80211_send_nullfunc(local, sdata, 1);
 
         local->hw.conf.flags |= IEEE80211_CONF_PS;