mac80211: fix deauth before assoc

When we receive a deauthentication frame before
having successfully associated, we neither print
a message nor abort assocation. The former makes
it hard to debug, while the latter later causes
a warning in cfg80211 when, as will typically be
the case, association timed out.

This warning was reported by many, e.g. in
https://bugzilla.kernel.org/show_bug.cgi?id=15981,
but I couldn't initially pinpoint it. I verified
the fix by hacking hostapd to send a deauth frame
instead of an association response.

Cc: stable@kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Tested-by: Miles Lane <miles.lane@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 38 insertions, 2 deletions

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 3310e70aa52f..f803f8b72a93 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1760,9 +1760,45 @@ static void ieee80211_sta_rx_queued_mgmt(struct ieee80211_sub_if_data *sdata,
         mutex_unlock(&ifmgd->mtx);
 
         if (skb->len >= 24 + 2 /* mgmt + deauth reason */ &&
-            (fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_DEAUTH)
-                cfg80211_send_deauth(sdata->dev, (u8 *)mgmt, skb->len);
+            (fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_DEAUTH) {
+                struct ieee80211_local *local = sdata->local;
+                struct ieee80211_work *wk;
+
+                mutex_lock(&local->work_mtx);
+                list_for_each_entry(wk, &local->work_list, list) {
+                        if (wk->sdata != sdata)
+                                continue;
+
+                        if (wk->type != IEEE80211_WORK_ASSOC)
+                                continue;
+
+                        if (memcmp(mgmt->bssid, wk->filter_ta, ETH_ALEN))
+                                continue;
+                        if (memcmp(mgmt->sa, wk->filter_ta, ETH_ALEN))
+                                continue;
 
+                        /*
+                         * Printing the message only here means we can't
+                         * spuriously print it, but it also means that it
+                         * won't be printed when the frame comes in before
+                         * we even tried to associate or in similar cases.
+                         *
+                         * Ultimately, I suspect cfg80211 should print the
+                         * messages instead.
+                         */
+                        printk(KERN_DEBUG
+                               "%s: deauthenticated from %pM (Reason: %u)\n",
+                               sdata->name, mgmt->bssid,
+                               le16_to_cpu(mgmt->u.deauth.reason_code));
+
+                        list_del_rcu(&wk->list);
+                        free_work(wk);
+                        break;
+                }
+                mutex_unlock(&local->work_mtx);
+
+                cfg80211_send_deauth(sdata->dev, (u8 *)mgmt, skb->len);
+        }
  out:
         kfree_skb(skb);
 }