4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Willem de Bruijn willemb@google.com
[ Upstream commit 993675a3100b16a4c80dfd70cbcde8ea7127b31d ]
If variable length link layer headers result in a packet shorter than dev->hard_header_len, reset the network header offset. Else skb->mac_len may exceed skb->len after skb_mac_reset_len.
packet_sendmsg_spkt already has similar logic.
Fixes: b84bbaf7a6c8 ("packet: in packet_snd start writing at link layer allocation") Signed-off-by: Willem de Bruijn willemb@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/packet/af_packet.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2917,6 +2917,8 @@ static int packet_snd(struct socket *soc goto out_free; } else if (reserve) { skb_reserve(skb, -reserve); + if (len < reserve) + skb_reset_network_header(skb); }
/* Returns -EFAULT on error */