mac80211: drop spoofed packets in ad-hoc mode

If an Ad-Hoc node receives packets with the Cell ID or its own MAC
address as source address, it hits a WARN_ON in sta_info_insert_check()
With many packets, this can massively spam the logs. One way that this
can easily happen is through having Cisco APs in the area with rouge AP
detection and countermeasures enabled.
Such Cisco APs will regularly send fake beacons, disassoc and deauth
packets that trigger these warnings.

To fix this issue, drop such spoofed packets early in the rx path.

Cc: stable@vger.kernel.org
Reported-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 54395d7583ba70e31111b08092c88d2901be7815..674eac1f996c9ddd664f2f70022514efc228b109 100644 (file)
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -3056,6 +3056,9 @@ static int prepare_for_handlers(struct ieee80211_rx_data *rx,
        case NL80211_IFTYPE_ADHOC:
                if (!bssid)
                        return 0;
+               if (ether_addr_equal(sdata->vif.addr, hdr->addr2) ||
+                   ether_addr_equal(sdata->u.ibss.bssid, hdr->addr2))
+                       return 0;
                if (ieee80211_is_beacon(hdr->frame_control)) {
                        return 1;
                } else if (!ieee80211_bssid_match(bssid, sdata->u.ibss.bssid)) {