cfg80211: validate AID of stations being added

We have some validation code in mac80211 but said code will
force an invalid AID to 0 which isn't a valid AID either;
instead require a valid AID (1-2007) to be passed in from
userspace in cfg80211 already. Also move the code before
the race comment since it can only be executed during STA
addition and thus is not racy.

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

2 files changed, 11 insertions, 6 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 77e9ff5ec4f3..cdfdb2eaad9f 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -664,18 +664,19 @@ static void sta_apply_parameters(struct ieee80211_local *local,
         spin_unlock_bh(&sta->lock);
 
         /*
+         * cfg80211 validates this (1-2007) and allows setting the AID
+         * only when creating a new station entry
+         */
+        if (params->aid)
+                sta->sta.aid = params->aid;
+
+        /*
          * FIXME: updating the following information is racy when this
          *        function is called from ieee80211_change_station().
          *        However, all this information should be static so
          *        maybe we should just reject attemps to change it.
          */
 
-        if (params->aid) {
-                sta->sta.aid = params->aid;
-                if (sta->sta.aid > IEEE80211_MAX_AID)
-                        sta->sta.aid = 0; /* XXX: should this be an error? */
-        }
-
         if (params->listen_interval >= 0)
                 sta->listen_interval = params->listen_interval;
 
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 4b4d3c8a1aed..19dc796bb0b8 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -1738,7 +1738,11 @@ static int nl80211_new_station(struct sk_buff *skb, struct genl_info *info)
                 nla_len(info->attrs[NL80211_ATTR_STA_SUPPORTED_RATES]);
         params.listen_interval =
                 nla_get_u16(info->attrs[NL80211_ATTR_STA_LISTEN_INTERVAL]);
+
         params.aid = nla_get_u16(info->attrs[NL80211_ATTR_STA_AID]);
+        if (!params.aid || params.aid > IEEE80211_MAX_AID)
+                return -EINVAL;
+
         if (info->attrs[NL80211_ATTR_HT_CAPABILITY])
                 params.ht_capa =
                         nla_data(info->attrs[NL80211_ATTR_HT_CAPABILITY]);