commit 6dbda2d00d466225f9db1dc695ff852443f28832
author Johannes Berg <johannes.berg@intel.com> Fri Oct 26 00:41:23 2012 +0200
committer Johannes Berg <johannes.berg@intel.com> Fri Oct 26 22:52:42 2012 +0200
tree 5a6df085d68670cbe478ab3cbed56e66fbd5bb24
parent 9b395bc3be1cebf0144a127c7e67d56dbdac0930

mac80211: make sure data is accessible in EAPOL check

The code to allow EAPOL frames even when the station
isn't yet marked associated needs to check that the
incoming frame is long enough and due to paged RX it
also can't assume skb->data contains the right data,
it must use skb_copy_bits(). Fix this to avoid using
data that doesn't really exist.

Cc: stable@vger.kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/rx.c

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 265a032d..00ade7f 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -888,14 +888,16 @@
 		 */
 		if (rx->sta && rx->sdata->vif.type == NL80211_IFTYPE_STATION &&
 		    ieee80211_is_data_present(hdr->frame_control)) {
-			u16 ethertype;
-			u8 *payload;
+			unsigned int hdrlen;
+			__be16 ethertype;
 
-			payload = rx->skb->data +
-				ieee80211_hdrlen(hdr->frame_control);
-			ethertype = (payload[6] << 8) | payload[7];
-			if (cpu_to_be16(ethertype) ==
-			    rx->sdata->control_port_protocol)
+			hdrlen = ieee80211_hdrlen(hdr->frame_control);
+
+			if (rx->skb->len < hdrlen + 8)
+				return RX_DROP_MONITOR;
+
+			skb_copy_bits(rx->skb, hdrlen + 6, &ethertype, 2);
+			if (ethertype == rx->sdata->control_port_protocol)
 				return RX_CONTINUE;
 		}