packet: round up linear to header len
authorWillem de Bruijn <willemb@google.com>
Tue, 7 Feb 2017 20:57:21 +0000 (15:57 -0500)
committerDavid S. Miller <davem@davemloft.net>
Wed, 8 Feb 2017 18:56:37 +0000 (13:56 -0500)
commit57031eb794906eea4e1c7b31dc1e2429c0af0c66
treeffe0e21da8d4ae2b435561434cc391970196e42b
parent217e6fa24ce28ec87fca8da93c9016cb78028612
packet: round up linear to header len

Link layer protocols may unconditionally pull headers, as Ethernet
does in eth_type_trans. Ensure that the entire link layer header
always lies in the skb linear segment. tpacket_snd has such a check.
Extend this to packet_snd.

Variable length link layer headers complicate the computation
somewhat. Here skb->len may be smaller than dev->hard_header_len.

Round up the linear length to be at least as long as the smallest of
the two.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/packet/af_packet.c