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From:   Felix Fietkau <nbd@nbd.name>
To:     linux-wireless@vger.kernel.org
Subject: [PATCH] mt76: do not access 802.11 header in ccmp check for 802.3 rx skbs
Date:   Mon, 11 Oct 2021 12:10:02 +0200
Message-Id: <20211011101002.53900-1-nbd@nbd.name>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Avoids false positive on detecting frags or encrypted mgmt frames

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 drivers/net/wireless/mediatek/mt76/mac80211.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mac80211.c b/drivers/net/wireless/mediatek/mt76/mac80211.c
index 5a6608f36ebc..766681a4f89e 100644
--- a/drivers/net/wireless/mediatek/mt76/mac80211.c
+++ b/drivers/net/wireless/mediatek/mt76/mac80211.c
@@ -974,6 +974,10 @@ mt76_check_ccmp_pn(struct sk_buff *skb)
 	if (!wcid || !wcid->rx_check_pn)
 		return 0;
 
+	security_idx = status->qos_ctl & IEEE80211_QOS_CTL_TID_MASK;
+	if (status->flag & RX_FLAG_8023)
+		goto skip_hdr_check;
+
 	hdr = mt76_skb_get_hdr(skb);
 	if (!(status->flag & RX_FLAG_IV_STRIPPED)) {
 		/*
@@ -994,9 +998,8 @@ mt76_check_ccmp_pn(struct sk_buff *skb)
 	if (ieee80211_is_mgmt(hdr->frame_control) &&
 	    !ieee80211_has_tods(hdr->frame_control))
 		security_idx = IEEE80211_NUM_TIDS;
-	else
-		security_idx = status->qos_ctl & IEEE80211_QOS_CTL_TID_MASK;
 
+skip_hdr_check:
 	BUILD_BUG_ON(sizeof(status->iv) != sizeof(wcid->rx_key_pn[0]));
 	ret = memcmp(status->iv, wcid->rx_key_pn[security_idx],
 		     sizeof(status->iv));
-- 
2.30.1