[PATCH net] net: 802: reset skb->transport_header

[Antonio Pastor <antonio.pastor@gmail.com>]

802.2+LLC+SNAP frames received by napi_complete_done() with GRO and DSA
have skb->transport_header set two bytes short, or pointing 2 bytes
before network_header & skb->data. This was an issue as snap_rcv()
expected offset to point to SNAP header (OID:PID), causing packet to
be dropped.

A fix at llc_fixup_skb() (a024e377efed) resets transport_header,
addressing the issue. This patch is additional clean up to snap_rcv()
so that it resets the offset after pulling the skb instead of
incrementing it to match the pull.

Fixes: fda55eca5a33 ("net: introduce skb_transport_header_was_set()")
Signed-off-by: Antonio Pastor <antonio.pastor@gmail.com>
---
 net/802/psnap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/802/psnap.c b/net/802/psnap.c
index fca9d454905f..252006f81afa 100644
--- a/net/802/psnap.c
+++ b/net/802/psnap.c
@@ -58,8 +58,8 @@ static int snap_rcv(struct sk_buff *skb, struct net_device *dev,
 	proto = find_snap_client(skb_transport_header(skb));
 	if (proto) {
 		/* Pass the frame on. */
-		skb->transport_header += 5;
 		skb_pull_rcsum(skb, 5);
+		skb_reset_transport_header(skb);
 		rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev);
 	}
 	rcu_read_unlock();
-- 
2.43.0