mac80211: fix memory corruption in EAPOL handling

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>

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index bde924968cd23e0b1eff384a237c73da725c83c7..b5848bcc09eb3239bae72a63d24a7c420ee7019d 100644 (file)
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2234,7 +2234,7 @@ ieee80211_deliver_skb(struct ieee80211_rx_data *rx)
 #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);