releases/2.6.25.8/virtio_net-fix-skb-csum_start-computation.patch

   1 From stable-bounces@linux.kernel.org Sun Jun 15 22:10:40 2008
   2 From: Mark McLoughlin <markmc@redhat.com>
   3 Date: Mon, 16 Jun 2008 14:41:41 +1000
   4 Subject: virtio_net: Fix skb->csum_start computation
   5 To: stable@kernel.org
   6 Cc: virtualization@lists.linux-foundation.org
   7 Message-ID: <200806161441.41993.rusty@rustcorp.com.au>
   8 Content-Disposition: inline
   9
  10
  11 From: Mark McLoughlin <markmc@redhat.com>
  12
  13 commit 23cde76d801246a702e7a84c3fe3d655b35c89a1 upstream.
  14
  15 hdr->csum_start is the offset from the start of the ethernet
  16 header to the transport layer checksum field. skb->csum_start
  17 is the offset from skb->head.
  18
  19 skb_partial_csum_set() assumes that skb->data points to the
  20 ethernet header - i.e. it computes skb->csum_start by adding
  21 the headroom to hdr->csum_start.
  22
  23 Since eth_type_trans() skb_pull()s the ethernet header,
  24 skb_partial_csum_set() should be called before
  25 eth_type_trans().
  26
  27 (Without this patch, GSO packets from a guest to the world outside the
  28 host are corrupted).
  29
  30 Signed-off-by: Mark McLoughlin <markmc@redhat.com>
  31 Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
  32 Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
  33 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  34
  35 ---
  36  drivers/net/virtio_net.c |    8 +++++---
  37  1 file changed, 5 insertions(+), 3 deletions(-)
  38
  39 --- a/drivers/net/virtio_net.c
  40 +++ b/drivers/net/virtio_net.c
  41 @@ -83,9 +83,7 @@ static void receive_skb(struct net_devic
  42         BUG_ON(len > MAX_PACKET_LEN);
  43
  44         skb_trim(skb, len);
  45 -       skb->protocol = eth_type_trans(skb, dev);
  46 -       pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
  47 -                ntohs(skb->protocol), skb->len, skb->pkt_type);
  48 +
  49         dev->stats.rx_bytes += skb->len;
  50         dev->stats.rx_packets++;
  51
  52 @@ -95,6 +93,10 @@ static void receive_skb(struct net_devic
  53                         goto frame_err;
  54         }
  55
  56 +       skb->protocol = eth_type_trans(skb, dev);
  57 +       pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
  58 +                ntohs(skb->protocol), skb->len, skb->pkt_type);
  59 +
  60         if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
  61                 pr_debug("GSO!\n");
  62                 switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {