From: Jesper Dangaard Brouer Date: Tue, 20 Feb 2018 13:32:10 +0000 (+0100) Subject: virtio_net: fix XDP code path in receive_small() X-Git-Tag: Ubuntu-4.15.0-34.37~405 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=36c3dce0c7dfdafa6230053bb3b7a093a53ff23d;p=mirror_ubuntu-bionic-kernel.git virtio_net: fix XDP code path in receive_small() BugLink: http://bugs.launchpad.net/bugs/1786352 [ 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 Acked-by: John Fastabend Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman Signed-off-by: Kamal Mostafa Signed-off-by: Khalid Elmously --- diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 69edfe25b224..bbb744570153 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -535,7 +535,7 @@ static struct sk_buff *receive_small(struct net_device *dev, 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))) {