[PATCH 5.4 33/85] macsec: avoid use-after-free in macsec_handle_frame()

From: Greg Kroah-Hartman
Date: Mon Oct 12 2020 - 09:42:48 EST


From: Eric Dumazet <edumazet@xxxxxxxxxx>

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 <edumazet@xxxxxxxxxx>
Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
Acked-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -1080,6 +1080,7 @@ 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 pn;
bool cbit;
@@ -1236,9 +1237,10 @@ 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++;