bpf: fix virtio-net's length calc for XDP_PASS

In commit 6870de435b90 ("bpf: make virtio compatible w/
bpf_xdp_adjust_tail") i didn't account for vi->hdr_len during new
packet's length calculation after bpf_prog_run in receive_mergeable.
because of this all packets, if they were passed to the kernel,
were truncated by 12 bytes.

Fixes:6870de435b90 ("bpf: make virtio compatible w/ bpf_xdp_adjust_tail")
Reported-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 3b5991734118ac4834e160a41c50894ba702cc49..f34794a76c4df71767edf5428d81d6187929d953 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -765,7 +765,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
                        /* recalculate len if xdp.data or xdp.data_end were
                         * adjusted
                         */
-                       len = xdp.data_end - xdp.data;
+                       len = xdp.data_end - xdp.data + vi->hdr_len;
                        /* We can only create skb based on xdp_page. */
                        if (unlikely(xdp_page != page)) {
                                rcu_read_unlock();