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net/packet: tpacket_rcv: do not increment ring index on drop

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In one error case, tpacket_rcv drops packets after incrementing the
ring producer index.

If this happens, it does not update tp_status to TP_STATUS_USER and
thus the reader is stalled for an iteration of the ring, causing out
of order arrival.

The only such error path is when virtio_net_hdr_from_skb fails due
to encountering an unknown GSO type.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Willem de Bruijn 2020-03-09 11:34:35 -04:00 committed by David S. Miller
parent f3cc008bf6
commit 46e4c421a0
1 changed files with 7 additions and 6 deletions
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13
net/packet/af_packet.c
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@ -2274,6 +2274,13 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
TP_STATUS_KERNEL, (macoff+snaplen)); TP_STATUS_KERNEL, (macoff+snaplen));
if (!h.raw) if (!h.raw)
goto drop_n_account; goto drop_n_account;
if (do_vnet &&
virtio_net_hdr_from_skb(skb, h.raw + macoff -
sizeof(struct virtio_net_hdr),
vio_le(), true, 0))
goto drop_n_account;
if (po->tp_version <= TPACKET_V2) { if (po->tp_version <= TPACKET_V2) {
packet_increment_rx_head(po, &po->rx_ring); packet_increment_rx_head(po, &po->rx_ring);
/* /*
@ -2286,12 +2293,6 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
status |= TP_STATUS_LOSING; status |= TP_STATUS_LOSING;
} }
if (do_vnet &&
virtio_net_hdr_from_skb(skb, h.raw + macoff -
sizeof(struct virtio_net_hdr),
vio_le(), true, 0))
goto drop_n_account;
po->stats.stats1.tp_packets++; po->stats.stats1.tp_packets++;
if (copy_skb) { if (copy_skb) {
status |= TP_STATUS_COPY; status |= TP_STATUS_COPY;