[PACKET]: Don't truncate non-linear skbs with mmaped IO

Non-linear skbs are truncated to their linear part with mmaped IO.
Fix by using skb_copy_bits instead of memcpy.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Acked-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 3 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index f9cef3671593..4172a5235916 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -626,8 +626,6 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, struct packe
                 if ((int)snaplen < 0)
                         snaplen = 0;
         }
-        if (snaplen > skb->len-skb->data_len)
-                snaplen = skb->len-skb->data_len;
 
         spin_lock(&sk->sk_receive_queue.lock);
         h = (struct tpacket_hdr *)packet_lookup_frame(po, po->head);
@@ -644,7 +642,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, struct packe
                 status &= ~TP_STATUS_LOSING;
         spin_unlock(&sk->sk_receive_queue.lock);
 
-        memcpy((u8*)h + macoff, skb->data, snaplen);
+        skb_copy_bits(skb, 0, (u8*)h + macoff, snaplen);
 
         h->tp_len = skb->len;
         h->tp_snaplen = snaplen;