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Re: mac80211 : fix unaligned rx skb

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matthieu castet wrote:
Michael Buesch wrote:
On Thursday 04 June 2009 23:16:13 Georgy Berdyshev wrote:
Hi,

that's the inline version:
-------
mac80211 is checking is the skb is aligned on 32 bit boundary.
But it is checking against ethernet header, whereas Linux expect IP
header aligned.
And ethernet ether size is 6*2+2=14, so aligning ethernet header make
IP header unaligned.

Signed-off-by: Matthieu CASTET <castet.matthieu@xxxxxxx>
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 9776f73..0845fb3 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -1397,7 +1397,7 @@ ieee80211_deliver_skb(struct ieee80211_rx_data *rx)
          * mac80211. That also explains the __skb_push()
          * below.
          */
-        align = (unsigned long)skb->data & 3;
+ align = ((unsigned long)(skb->data + sizeof(struct ethhdr))) & 3;
         if (align) {
             if (WARN_ON(skb_headroom(skb) < 3)) {
                 dev_kfree_skb(skb);

Uhm, can you give a more verbose explanation? Without that I'd say this patch is plain wrong.
What the hell does struct ethhdr have to do with wireless?
 > This is not ethernet. It's 802.11. There is no such thing as an
 > ethernet header in a 802.11 packet.
 >
Where are in ieee80211_deliver_skb that is called after ieee80211_data_to_8023. So it is not 802.11.

Do you want more explanation ?

Matthieu
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