From: Jakub Kicinski <jakub.kicinski@netronome.com>
Date: Tue, 22 Aug 2017 23:22:44 -0700
Subject: nfp: avoid buffer leak when representor is missing
Patch-mainline: v4.13
Git-commit: 1691a4c0f4634d50ffeb74373fdeec63495c911e
References: bsc#1055968

When driver receives a muxed frame, but it can't find the representor
netdev it is destined to it will try to "drop" that frame, i.e. reuse
the buffer.  The issue is that the replacement buffer has already been
allocated at this point, and reusing the buffer from received frame
will leak it.  Change the code to put the new buffer on the ring
earlier and not reuse the old buffer (make the buffer parameter
to nfp_net_rx_drop() a NULL).

Fixes: 91bf82ca9eed ("nfp: add support for tx/rx with metadata portid")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/netronome/nfp/nfp_net_common.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
@@ -1751,6 +1751,10 @@ static int nfp_net_rx(struct nfp_net_rx_
 			continue;
 		}
 
+		nfp_net_dma_unmap_rx(dp, rxbuf->dma_addr);
+
+		nfp_net_rx_give_one(dp, rx_ring, new_frag, new_dma_addr);
+
 		if (likely(!meta.portid)) {
 			netdev = dp->netdev;
 		} else {
@@ -1759,16 +1763,12 @@ static int nfp_net_rx(struct nfp_net_rx_
 			nn = netdev_priv(dp->netdev);
 			netdev = nfp_app_repr_get(nn->app, meta.portid);
 			if (unlikely(!netdev)) {
-				nfp_net_rx_drop(dp, r_vec, rx_ring, rxbuf, skb);
+				nfp_net_rx_drop(dp, r_vec, rx_ring, NULL, skb);
 				continue;
 			}
 			nfp_repr_inc_rx_stats(netdev, pkt_len);
 		}
 
-		nfp_net_dma_unmap_rx(dp, rxbuf->dma_addr);
-
-		nfp_net_rx_give_one(dp, rx_ring, new_frag, new_dma_addr);
-
 		skb_reserve(skb, pkt_off);
 		skb_put(skb, pkt_len);