nfp: fix potential use after free on xdp prog

We should unregister the net_device first, before we give back
our reference on xdp_prog.  Otherwise xdp_prog may be freed
before .ndo_stop() disabled the datapath.  Found by code inspection.

Fixes: ecd63a0217d5 ("nfp: add XDP support in the driver")
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>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
index 9179a99563af..a41377e26c07 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
@@ -3275,9 +3275,10 @@ void nfp_net_netdev_clean(struct net_device *netdev)
 {
         struct nfp_net *nn = netdev_priv(netdev);
 
+        unregister_netdev(nn->netdev);
+
         if (nn->xdp_prog)
                 bpf_prog_put(nn->xdp_prog);
         if (nn->bpf_offload_xdp)
                 nfp_net_xdp_offload(nn, NULL);
-        unregister_netdev(nn->netdev);
 }