[PATCH 3.16 265/305] mac80211: ignore NullFunc frames in the duplicate detection

[Ben Hutchings]

3.16.63-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Emmanuel Grumbach <emmanuel.grumbach@xxxxxxxxx>

commit 990d71846a0b7281bd933c34d734e6afc7408e7e upstream.

NullFunc packets should never be duplicate just like
QoS-NullFunc packets.

We saw a client that enters / exits power save with
NullFunc frames (and not with QoS-NullFunc) despite the
fact that the association supports HT.
This specific client also re-uses a non-zero sequence number
for different NullFunc frames.
At some point, the client had to send a retransmission of
the NullFunc frame and we dropped it, leading to a
misalignment in the power save state.
Fix this by never consider a NullFunc frame as duplicate,
just like we do for QoS NullFunc frames.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=201449

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@xxxxxxxxx>
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
[bwh: Backported to 3.16: The condition for "should we check for duplication"
 is in ieee80211_rx_h_check() and is not inverted]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/mac80211/rx.c | 1 +
 1 file changed, 1 insertion(+)

--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -967,6 +967,7 @@ ieee80211_rx_h_check(struct ieee80211_rx
 	 */
 	if (rx->skb->len >= 24 && rx->sta &&
 	    !ieee80211_is_ctl(hdr->frame_control) &&
+	    !ieee80211_is_nullfunc(hdr->frame_control) &&
 	    !ieee80211_is_qos_nullfunc(hdr->frame_control) &&
 	    !is_multicast_ether_addr(hdr->addr1)) {
 		if (unlikely(ieee80211_has_retry(hdr->frame_control) &&