mac80211: pass in PS_POLL frames

This patch fixes should_drop_frame function to pass in ps poll control
frames required for power save functioanlity. Interface types that do not
have interest for PS POLL frames now drop it in handler.

Signed-off-by: Ron Rindjunsky <ron.rindjunsky@intel.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 7b278e9..fb7fd89 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -135,13 +135,16 @@
 {
 	u16 fc;
 
-	if (len < 24)
+	 /* drop ACK/CTS frames and incorrect hdr len (ctrl) */
+	if (len < 16)
 		return NULL;
 
 	fc = le16_to_cpu(hdr->frame_control);
 
 	switch (fc & IEEE80211_FCTL_FTYPE) {
 	case IEEE80211_FTYPE_DATA:
+		if (len < 24) /* drop incorrect hdr len (data) */
+			return NULL;
 		switch (fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) {
 		case IEEE80211_FCTL_TODS:
 			return hdr->addr1;
@@ -154,6 +157,8 @@
 		}
 		break;
 	case IEEE80211_FTYPE_MGMT:
+		if (len < 24) /* drop incorrect hdr len (mgmt) */
+			return NULL;
 		return hdr->addr3;
 	case IEEE80211_FTYPE_CTL:
 		if ((fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_PSPOLL)