mac80211: mesh: fix two small problems

1) there's a spin_lock() that needs to be spin_lock_bh()
2) action frames of size 24 might cause an out-of-bounds
   memory access (for the 25th byte only, so no big deal)

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
index 542ea02..8a97b14 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -685,9 +685,12 @@
 	fc = le16_to_cpu(mgmt->frame_control);
 
 	switch (fc & IEEE80211_FCTL_STYPE) {
+	case IEEE80211_STYPE_ACTION:
+		if (skb->len < IEEE80211_MIN_ACTION_SIZE)
+			return RX_DROP_MONITOR;
+		/* fall through */
 	case IEEE80211_STYPE_PROBE_RESP:
 	case IEEE80211_STYPE_BEACON:
-	case IEEE80211_STYPE_ACTION:
 		skb_queue_tail(&ifmsh->skb_queue, skb);
 		queue_work(local->hw.workqueue, &ifmsh->work);
 		return RX_QUEUED;