mac80211: drop robust management frames from unknown TA

BugLink: https://bugs.launchpad.net/bugs/1836668

commit 588f7d39 upstream.

When receiving a robust management frame, drop it if we don't have
rx->sta since then we don't have a security association and thus
couldn't possibly validate the frame.

Cc: stable@vger.kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

net/mac80211/rx.c

@@ -3324,6 +3324,8 @@ static bool ieee80211_accept_frame(struct ieee80211_rx_data *rx)
 	case NL80211_IFTYPE_STATION:
 		if (!bssid && !sdata->u.mgd.use_4addr)
 			return false;
+		if (ieee80211_is_robust_mgmt_frame(skb) && !rx->sta)
+			return false;
 		if (multicast)
 			return true;
 		return ether_addr_equal(sdata->vif.addr, hdr->addr1);