[PATCH 4.4 126/188] mac80211: fix memory corruption in EAPOL handling

Greg Kroah-Hartman
2021-07-19T15:02:34Z

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
@@ -2234,7 +2234,7 @@ 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);