mac80211: fix AP/VLAN PS buffer race

When an AP interface is removed without the
AP/VLAN interfaces having been removed before
already, the AP-VLAN interface might still
have sleeping stations and buffer multicast
frames which will happen on the AP interface.
Thus, we need to remove AP/VLAN interfaces
before purging buffered broadcast frames.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 4 insertions, 6 deletions

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index eaa80a3d412b..4116a7542b6b 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -460,17 +460,15 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
                 synchronize_rcu();
                 kfree(old_beacon);
 
-                /* free all potentially still buffered bcast frames */
-                while ((skb = skb_dequeue(&sdata->u.ap.ps_bc_buf))) {
-                        local->total_ps_buffered--;
-                        dev_kfree_skb(skb);
-                }
-
                 /* down all dependent devices, that is VLANs */
                 list_for_each_entry_safe(vlan, tmpsdata, &sdata->u.ap.vlans,
                                          u.vlan.list)
                         dev_close(vlan->dev);
                 WARN_ON(!list_empty(&sdata->u.ap.vlans));
+
+                /* free all potentially still buffered bcast frames */
+                local->total_ps_buffered -= skb_queue_len(&sdata->u.ap.ps_bc_buf);
+                skb_queue_purge(&sdata->u.ap.ps_bc_buf);
         }
 
         if (going_down)