packet: round up linear to header len
[ Upstream commit 57031eb794906eea4e1c7b31dc1e2429c0af0c66 ]
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 94e4a59..458722b 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2813,7 +2813,7 @@
struct virtio_net_hdr vnet_hdr = { 0 };
int offset = 0;
struct packet_sock *po = pkt_sk(sk);
- int hlen, tlen;
+ int hlen, tlen, linear;
int extra_len = 0;
/*
@@ -2874,8 +2874,9 @@
err = -ENOBUFS;
hlen = LL_RESERVED_SPACE(dev);
tlen = dev->needed_tailroom;
- skb = packet_alloc_skb(sk, hlen + tlen, hlen, len,
- __virtio16_to_cpu(vio_le(), vnet_hdr.hdr_len),
+ linear = __virtio16_to_cpu(vio_le(), vnet_hdr.hdr_len);
+ linear = max(linear, min_t(int, len, dev->hard_header_len));
+ skb = packet_alloc_skb(sk, hlen + tlen, hlen, len, linear,
msg->msg_flags & MSG_DONTWAIT, &err);
if (skb == NULL)
goto out_unlock;