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Commit 8c76e77f authored by Willem de Bruijn's avatar Willem de Bruijn Committed by David S. Miller
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tap: call skb_probe_transport_header after setting skb->dev 



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: d0e13a14 ("flow_dissector: lookup netns by skb->sk if skb->dev is NULL")
Reported-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent aff6db45

drivers/net/tap.c

+1 −2
Original line number Diff line number Diff line
@@ -1177,8 +1177,6 @@ static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp) 
			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_queue *q, struct xdp_buff *xdp) 
	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);