4.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Felix Fietkau <[email protected]>

commit c041778c966c92c964033f1cdfee60a9f2b5e465 upstream.

The PDU length of incoming LLC frames is set to the total skb payload size
in __ieee80211_data_to_8023() of net/wireless/util.c which incorrectly
includes the length of the IEEE 802.11 header.

The resulting LLC frame header has a too large PDU length, causing the
llc_fixup_skb() function of net/llc/llc_input.c to reject the incoming
skb, effectively breaking STP.

Solve the problem by properly substracting the IEEE 802.11 frame header size
from the PDU length, allowing the LLC processor to pick up the incoming
control messages.

Special thanks to Gerry Rozema for tracking down the regression and proposing
a suitable patch.

Fixes: 2d1c304cb2d5 ("cfg80211: add function for 802.3 conversion with separate 
output buffer")
Reported-by: Gerry Rozema <[email protected]>
Signed-off-by: Felix Fietkau <[email protected]>
Signed-off-by: Johannes Berg <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 net/wireless/util.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -509,7 +509,7 @@ static int __ieee80211_data_to_8023(stru
                 * replace EtherType */
                hdrlen += ETH_ALEN + 2;
        else
-               tmp.h_proto = htons(skb->len);
+               tmp.h_proto = htons(skb->len - hdrlen);
 
        pskb_pull(skb, hdrlen);
 


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