[PATCH 3.5 03/78] mac80211: drop spoofed packets in ad-hoc mode

[Luis Henriques]

3.5.7.26 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Felix Fietkau <nbd at openwrt.org>

commit 6329b8d917adc077caa60c2447385554130853a3 upstream.

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.

Reported-by: Thomas Huehn <thomas at net.t-labs.tu-berlin.de>
Signed-off-by: Felix Fietkau <nbd at openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg at intel.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/mac80211/rx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index d419c47..ee8f525a 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2823,6 +2823,9 @@ 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;
 		}
-- 
1.8.3.2