WARNING from mac80211

[Larry Finger <Larry.Finger@lwfinger.net>]

Johannes and John,

A regression in recent versions of mac80211 are generating the WARNING at 
net/mac80211/wep.c:101, because the skb headroom is less than WEP_IV_LEN or the 
tailroom is less than WEP_ICV_LEN. My testing indicates that it is a headroom 
problem as the following hack "fixes" it:

Index: wireless-testing-new/net/mac80211/tx.c
===================================================================
--- wireless-testing-new.orig/net/mac80211/tx.c
+++ wireless-testing-new/net/mac80211/tx.c
@@ -1935,6 +1935,8 @@ netdev_tx_t ieee80211_subif_start_xmit(s
                 head_need += IEEE80211_ENCRYPT_HEADROOM;
                 head_need += local->tx_headroom;
                 head_need = max_t(int, 0, head_need);
+               if (head_need < WEP_IV_LEN)
+                       head_need = WEP_IV_LEN;
                 if (ieee80211_skb_resize(local, skb, head_need, true))
                         goto fail;
         }

I'm certain that this is too simple minded, but it at least points to a place to 
look. I have not bisected the problem to see which commit caused the regression, 
but I can if you want.

Larry