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virtio_net: fix XDP code path in receive_small() 

When configuring virtio_net to use the code path 'receive_small()',
in-order to get correct XDP_REDIRECT support, I discovered TCP packets
would get silently dropped when loading an XDP program action XDP_PASS.

The bug seems to be that receive_small() when XDP is loaded check that
hdr->hdr.flags is zero, which seems wrong as hdr.flags contains the
flags VIRTIO_NET_HDR_F_* :
 #define VIRTIO_NET_HDR_F_NEEDS_CSUM 1 /* Use csum_start, csum_offset */
 #define VIRTIO_NET_HDR_F_DATA_VALID 2 /* Csum is valid */

TCP got dropped as it had the VIRTIO_NET_HDR_F_DATA_VALID flag set.

The flags that are relevant here are the VIRTIO_NET_HDR_GSO_* flags
stored in hdr->hdr.gso_type. Thus, the fix is just check that none of
the gso_type flags have been set.

Fixes: bb91accf27 ("virtio-net: XDP support for small buffers")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jesper Dangaard Brouer 2018-02-20 14:32:10 +01:00 committed by David S. Miller
parent 7324f5399b
commit 95dbe9e7b3
1 changed files with 1 additions and 1 deletions
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2
drivers/net/virtio_net.c
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@ -558,7 +558,7 @@ static struct sk_buff *receive_small(struct net_device *dev,
void *orig_data; void *orig_data;
u32 act; u32 act;
if (unlikely(hdr->hdr.gso_type || hdr->hdr.flags)) if (unlikely(hdr->hdr.gso_type))
goto err_xdp; goto err_xdp;
if (unlikely(xdp_headroom < virtnet_get_headroom(vi))) { if (unlikely(xdp_headroom < virtnet_get_headroom(vi))) {