mac80211: Ensure tid_start_tx is protected by sta->lock

All accesses of the tid_start_tx lock should be protected
by sta->lock if there is any chance that another thread
could still be accessing the sta object.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

2 files changed, 4 insertions, 1 deletions

diff --git a/net/mac80211/ht.c b/net/mac80211/ht.c
index 75dff338f581..f83534f6a2ee 100644
--- a/net/mac80211/ht.c
+++ b/net/mac80211/ht.c
@@ -281,13 +281,14 @@ void ieee80211_ba_session_work(struct work_struct *work)
                                 sta, tid, WLAN_BACK_RECIPIENT,
                                 WLAN_REASON_UNSPECIFIED, true);
 
+                spin_lock_bh(&sta->lock);
+
                 tid_tx = sta->ampdu_mlme.tid_start_tx[tid];
                 if (tid_tx) {
                         /*
                          * Assign it over to the normal tid_tx array
                          * where it "goes live".
                          */
-                        spin_lock_bh(&sta->lock);
 
                         sta->ampdu_mlme.tid_start_tx[tid] = NULL;
                         /* could there be a race? */
@@ -300,6 +301,7 @@ void ieee80211_ba_session_work(struct work_struct *work)
                         ieee80211_tx_ba_session_handle_start(sta, tid);
                         continue;
                 }
+                spin_unlock_bh(&sta->lock);
 
                 tid_tx = rcu_dereference_protected_tid_tx(sta, tid);
                 if (tid_tx && test_and_clear_bit(HT_AGG_STATE_WANT_STOP,
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index bd12fc54266c..4208dbd5861f 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -203,6 +203,7 @@ struct tid_ampdu_rx {
  *      driver requested to close until the work for it runs
  * @mtx: mutex to protect all TX data (except non-NULL assignments
  *      to tid_tx[idx], which are protected by the sta spinlock)
+ *      tid_start_tx is also protected by sta->lock.
  */
 struct sta_ampdu_mlme {
         struct mutex mtx;