[PATCH 4.20 005/145] tap: call skb_probe_transport_header after setting skb->dev
From: Greg Kroah-Hartman
Date: Mon Jan 07 2019 - 07:34:08 EST
4.20-stable review patch. If anyone has any objections, please let me know.
------------------
From: Willem de Bruijn <willemb@xxxxxxxxxx>
[ Upstream commit 8c76e77f9069f10505c08e02646c3ee11ad79038 ]
The BPF flow dissector expects either skb->sk or skb->dev set on
all skbs. Delay flow dissection until after skb->dev is set.
This requires calling from within an rcu read-side critical section.
That is fine, see also the call from tun_xdp_one.
Fixes: d0e13a1488ad ("flow_dissector: lookup netns by skb->sk if skb->dev is NULL")
Reported-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Signed-off-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/tap.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -1177,8 +1177,6 @@ static int tap_get_user_xdp(struct tap_q
goto err_kfree;
}
- skb_probe_transport_header(skb, ETH_HLEN);
-
/* Move network header to the right position for VLAN tagged packets */
if ((skb->protocol == htons(ETH_P_8021Q) ||
skb->protocol == htons(ETH_P_8021AD)) &&
@@ -1189,6 +1187,7 @@ static int tap_get_user_xdp(struct tap_q
tap = rcu_dereference(q->tap);
if (tap) {
skb->dev = tap->dev;
+ skb_probe_transport_header(skb, ETH_HLEN);
dev_queue_xmit(skb);
} else {
kfree_skb(skb);