Re: regression: tethering fails in 3.5 with iwlwifi

Or its a buggy protocol ?

IP/UDP/TCP definitely works, but maybe another protocol assumes its
header is in skb->head


On Thu, Sep 20, 2012 at 2:47 PM, Johannes Berg
[off-list ref] wrote:

On Thu, 2012-09-20 at 14:45 +0200, Eric Dumazet wrote:

quoted

I guess you only need to make sure 14 bytes of ethernet header are
available before eth_type_trans(skb, dev);

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 61c621e..ffe5f84 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c

@@ -1795,9 +1795,13 @@ ieee80211_deliver_skb(struct ieee80211_rx_data *rx)

                if (skb) {
                        /* deliver to local stack */
-                       skb->protocol = eth_type_trans(skb, dev);
-                       memset(skb->cb, 0, sizeof(skb->cb));
-                       netif_receive_skb(skb);
+                       if (pskb_may_pull(skb, sizeof(struct ethhdr))) {
+                               skb->protocol = eth_type_trans(skb, dev);
+                               memset(skb->cb, 0, sizeof(skb->cb));
+                               netif_receive_skb(skb);
+                       } else {
+                               kfree_skb(skb);
+                       }
                }
        }

Yeah I was looking at the same code just now. However, we had actually
inserted the skb_linearize() *after* eth_type_trans(), so I'm confused.
Maybe it still works, more or less by accident?

johannes

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On Thu, 2012-09-20 at 14:48 +0200, Eric Dumazet wrote:

Or its a buggy protocol ?

IP/UDP/TCP definitely works, but maybe another protocol assumes its
header is in skb->head

It could be, I think it failed either on EAPOL (which is just userspace
registering a protocol socket) or DHCP (same?)

johannes