mac80211: don't WARN on short WMM parameters from AP

commit 05aaa5c97dce4c10a9e7eae2f1569a684e0c5ced upstream.

In a very similar spirit to commit c470bdc1aaf3 ("mac80211: don't WARN
on bad WMM parameters from buggy APs"), an AP may not transmit a
fully-formed WMM IE. For example, it may miss or repeat an Access
Category. The above loop won't catch that and will instead leave one of
the four ACs zeroed out. This triggers the following warning in
drv_conf_tx()

  wlan0: invalid CW_min/CW_max: 0/0

and it may leave one of the hardware queues unconfigured. If we detect
such a case, let's just print a warning and fall back to the defaults.

Tested with a hacked version of hostapd, intentionally corrupting the
IEs in hostapd_eid_wmm().

Cc: stable@vger.kernel.org
Signed-off-by: Brian Norris <briannorris@chromium.org>
Link: https://lore.kernel.org/r/20190726224758.210953-1-briannorris@chromium.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index d787717140e54f1cd3a46063da06d71c2211b49d..f462f026fc6aa0ae9146d04ab5838c6382fe7a20 100644 (file)
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1873,6 +1873,16 @@ static bool ieee80211_sta_wmm_params(struct ieee80211_local *local,
                }
        }
 
+       /* WMM specification requires all 4 ACIs. */
+       for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
+               if (params[ac].cw_min == 0) {
+                       sdata_info(sdata,
+                                  "AP has invalid WMM params (missing AC %d), using defaults\n",
+                                  ac);
+                       return false;
+               }
+       }
+
        for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
                mlme_dbg(sdata,
                         "WMM AC=%d acm=%d aifs=%d cWmin=%d cWmax=%d txop=%d uapsd=%d, downgraded=%d\n",