On Fri, Nov 28, 2014 at 08:10:03PM -0200, Marcelo Ricardo Leitner wrote:

quoted

Could you print vnet_hdr_sz and sizeof(gso) right after that
copy_from_iter(&gso, ...)?

Did a:
        else {
                err = skb_copy_datagram_from_iter(skb, 0, from, len);
+               pr_err("vnet_hdr_sz=%d sizeof(gso)=%lu\n",
tun->vnet_hdr_sz, sizeof(gso));
                if (!err && msg_control) {

Got, for tun:
[   50.514165] tun: vnet_hdr_sz=12 sizeof(gso)=10

for tap:
[   82.911840] tun: vnet_hdr_sz=10 sizeof(gso)=10

other values were just as before.

Hmm...  Do you have
commit 8c847d254146d32c86574a1b16923ff91bb784dd
Author: Jason Wang [off-list ref]
Date:   Thu Nov 13 16:54:14 2014 +0800

    tun: fix issues of iovec iterators using in tun_put_user()
in your tree?