On Tue, Dec 10, 2013 at 01:49:45PM +0800, Jason Wang wrote:
> Commit 6680ec68eff47d36f67b4351bc9836fd6cba9532
> (tuntap: hardware vlan tx support) breaks the truncated packet signal by nev
> return a length greater than iov length in tun_put_user(). This patch fixes
> by always return the length of packet plus possible vlan header. Caller can
> detect the truncated packet by comparing the return value and the size of io
> length.
>
> Cc: Zhi Yong Wu <wu...@linux.vnet.ibm.com>
> Cc: Michael S. Tsirkin <m...@redhat.com>
> Signed-off-by: Vlad Yasevich <vyasev...@gmail.com>
> Signed-off-by: Jason Wang <jasow...@redhat.com>
> ---
> Changes from v1:
> - increase total unconditionally
> - do not move veth structure out of the vlan handing block
> ---
> drivers/net/tun.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index e26cbea..cd142134 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -1184,7 +1184,7 @@ static ssize_t tun_put_user(struct tun_struct *tun,
> {
> struct tun_pi pi = { 0, skb->protocol };
> ssize_t total = 0;
> - int vlan_offset = 0;
> + int vlan_offset = 0, offset;
>
> if (!(tun->flags & TUN_NO_PI)) {
> if ((len -= sizeof(pi)) < 0)
> @@ -1248,6 +1248,8 @@ static ssize_t tun_put_user(struct tun_struct *tun,
> total += tun->vnet_hdr_sz;
> }
>
> + offset = total;
> + total += skb->len;
> if (!vlan_tx_tag_present(skb)) {
> len = min_t(int, skb->len, len);
> } else {
> @@ -1262,24 +1264,24 @@ static ssize_t tun_put_user(struct tun_struct *tun,
>
> vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
> len = min_t(int, skb->len + VLAN_HLEN, len);
> + total += VLAN_HLEN;
>
> copy = min_t(int, vlan_offset, len);
> - ret = skb_copy_datagram_const_iovec(skb, 0, iv, total, copy);
> + ret = skb_copy_datagram_const_iovec(skb, 0, iv, offset, copy);
> len -= copy;
> - total += copy;
> + offset += copy;
> if (ret || !len)
> goto done;
>
> copy = min_t(int, sizeof(veth), len);
> - ret = memcpy_toiovecend(iv, (void *)&veth, total, copy);
> + ret = memcpy_toiovecend(iv, (void *)&veth, offset, copy);
> len -= copy;
> - total += copy;
> + offset += copy;
> if (ret || !len)
> goto done;
> }
>
> - skb_copy_datagram_const_iovec(skb, vlan_offset, iv, total, len);
> - total += len;
> + skb_copy_datagram_const_iovec(skb, vlan_offset, iv, offset, len);
>
> done:
> tun->dev->stats.tx_packets++;
offset is not descriptive. I would call new variable "copied",
and change all code to use that, do
total = copied + skb->len, total is then the total length.
> --
> 1.8.3.2
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