mac80211: clear sequence/fragment number in QoS-null frames

Avoid leaking data by sending uninitialized memory and setting an
invalid (non-zero) fragment number (the sequence number is ignored
anyway) by setting the seq_ctrl field to zero.

Cc: stable@vger.kernel.org
Fixes: 3f52b7e3 ("mac80211: mesh power save basics")
Fixes: ce662b44 ("mac80211: send (QoS) Null if no buffered frames")
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mesh_ps.c

@@ -36,6 +36,7 @@ static struct sk_buff *mps_qos_null_get(struct sta_info *sta)
 				      sdata->vif.addr);
 	nullfunc->frame_control = fc;
 	nullfunc->duration_id = 0;
+	nullfunc->seq_ctrl = 0;
 	/* no address resolution for this frame -> set addr 1 immediately */
 	memcpy(nullfunc->addr1, sta->sta.addr, ETH_ALEN);
 	memset(skb_put(skb, 2), 0, 2); /* append QoS control field */

net/mac80211/sta_info.c

@@ -1206,6 +1206,7 @@ static void ieee80211_send_null_response(struct ieee80211_sub_if_data *sdata,
 	memcpy(nullfunc->addr1, sta->sta.addr, ETH_ALEN);
 	memcpy(nullfunc->addr2, sdata->vif.addr, ETH_ALEN);
 	memcpy(nullfunc->addr3, sdata->vif.addr, ETH_ALEN);
+	nullfunc->seq_ctrl = 0;
 
 	skb->priority = tid;
 	skb_set_queue_mapping(skb, ieee802_1d_to_ac[tid]);