Commit 993675a3 authored Jul 11, 2018 by Willem de Bruijn Committed by David S. Miller Jul 12, 2018

packet: reset network header if packet shorter than ll reserved space



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: b84bbaf7 ("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>

parent bab2c80e

net/packet/af_packet.c

+2 −0

Original line number	Original line	Diff line number	Diff line
	@@ -2878,6 +2878,8 @@ static int packet_snd(struct socket sock, struct msghdr msg, size_t len)
	goto out_free;		goto out_free;
	} else if (reserve) {		} else if (reserve) {
	skb_reserve(skb, -reserve);		skb_reserve(skb, -reserve);
			if (len < reserve)
			skb_reset_network_header(skb);
	}		}

	/* Returns -EFAULT on error */		/* Returns -EFAULT on error */