From 6b0f32745dcfba01d7be33acd1b40306c7a914c6 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Thu, 11 Jul 2013 22:33:26 +0200 Subject: [PATCH] mac80211: fix duplicate retransmission detection The duplicate retransmission detection code in mac80211 erroneously attempts to do the check for every frame, even frames that don't have a sequence control field or that don't use it (QoS-Null frames.) This is problematic because it causes the code to access data beyond the end of the SKB and depending on the data there will drop packets erroneously. Correct the code to not do duplicate detection for such frames. I found this error while testing AP powersave, it lead to retransmitted PS-Poll frames being dropped entirely as the data beyond the end of the SKB was always zero. Cc: stable@vger.kernel.org [all versions] Signed-off-by: Johannes Berg --- net/mac80211/rx.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c index 23dbcfc69b3b..2c5a79bd3777 100644 --- a/net/mac80211/rx.c +++ b/net/mac80211/rx.c @@ -936,8 +936,14 @@ ieee80211_rx_h_check(struct ieee80211_rx_data *rx) struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data; struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb); - /* Drop duplicate 802.11 retransmissions (IEEE 802.11 Chap. 9.2.9) */ - if (rx->sta && !is_multicast_ether_addr(hdr->addr1)) { + /* + * Drop duplicate 802.11 retransmissions + * (IEEE 802.11-2012: 9.3.2.10 "Duplicate detection and recovery") + */ + if (rx->skb->len >= 24 && rx->sta && + !ieee80211_is_ctl(hdr->frame_control) && + !ieee80211_is_qos_nullfunc(hdr->frame_control) && + !is_multicast_ether_addr(hdr->addr1)) { if (unlikely(ieee80211_has_retry(hdr->frame_control) && rx->sta->last_seq_ctrl[rx->seqno_idx] == hdr->seq_ctrl)) {