[PATCH 5.8 027/124] macsec: avoid use-after-free in macsec_handle_frame()

[Greg Kroah-Hartman]

From: Eric Dumazet <eduma...@google.com>

commit c7cc9200e9b4a2ac172e990ef1975cd42975dad6 upstream.

De-referencing skb after call to gro_cells_receive() is not allowed.
We need to fetch skb->len earlier.

Fixes: 5491e7c6b1a9 ("macsec: enable GRO and RPS on macsec devices")
Signed-off-by: Eric Dumazet <eduma...@google.com>
Cc: Paolo Abeni <pab...@redhat.com>
Acked-by: Paolo Abeni <pab...@redhat.com>
Signed-off-by: Jakub Kicinski <k...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/net/macsec.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -1077,6 +1077,7 @@ static rx_handler_result_t macsec_handle
        struct macsec_rx_sa *rx_sa;
        struct macsec_rxh_data *rxd;
        struct macsec_dev *macsec;
+       unsigned int len;
        sci_t sci;
        u32 hdr_pn;
        bool cbit;
@@ -1232,9 +1233,10 @@ deliver:
        macsec_rxsc_put(rx_sc);
 
        skb_orphan(skb);
+       len = skb->len;
        ret = gro_cells_receive(&macsec->gro_cells, skb);
        if (ret == NET_RX_SUCCESS)
-               count_rx(dev, skb->len);
+               count_rx(dev, len);
        else
                macsec->secy.netdev->stats.rx_dropped++;