4.14-stable review patch. If anyone has any objections, please let me know.
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From: Jesper Dangaard Brouer brouer@redhat.com
[ Upstream commit 95dbe9e7b3720efa5cf83d21f44f6d953f7cf4a2 ]
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: bb91accf2733 ("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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/virtio_net.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -513,7 +513,7 @@ static struct sk_buff *receive_small(str void *orig_data; u32 act;
- if (unlikely(hdr->hdr.gso_type || hdr->hdr.flags)) + if (unlikely(hdr->hdr.gso_type)) goto err_xdp;
if (unlikely(xdp_headroom < virtnet_get_headroom(vi))) {