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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org, johannes@sipsolutions.net
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        "linux-wireless@vger.kernel.org, stable@vger.kernel.org, Davis Mosenkovs" 
        <davis@mosenkovs.lv>, Davis Mosenkovs <davis@mosenkovs.lv>
Subject: [PATCH 4.9 160/245] mac80211: fix memory corruption in EAPOL handling
Date:   Mon, 19 Jul 2021 16:51:42 +0200
Message-Id: <20210719144945.576632083@linuxfoundation.org>
In-Reply-To: <20210719144940.288257948@linuxfoundation.org>
References: <20210719144940.288257948@linuxfoundation.org>
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From: Davis Mosenkovs <davis@mosenkovs.lv>

Commit e3d4030498c3 ("mac80211: do not accept/forward invalid EAPOL
frames") uses skb_mac_header() before eth_type_trans() is called
leading to incorrect pointer, the pointer gets written to. This issue
has appeared during backporting to 4.4, 4.9 and 4.14.

Fixes: e3d4030498c3 ("mac80211: do not accept/forward invalid EAPOL frames")
Link: https://lore.kernel.org/r/CAHQn7pKcyC_jYmGyTcPCdk9xxATwW5QPNph=bsZV8d-HPwNsyA@mail.gmail.com
Cc: <stable@vger.kernel.org> # 4.4.x
Signed-off-by: Davis Mosenkovs <davis@mosenkovs.lv>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/mac80211/rx.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2380,7 +2380,7 @@ ieee80211_deliver_skb(struct ieee80211_r
 #endif
 
 	if (skb) {
-		struct ethhdr *ehdr = (void *)skb_mac_header(skb);
+		struct ethhdr *ehdr = (struct ethhdr *)skb->data;
 
 		/* deliver to local stack */
 		skb->protocol = eth_type_trans(skb, dev);