sfc: Add length checks to efx_xmit_with_hwtstamp() and efx_ptp_is_ptp_tx()

efx_ptp_is_ptp_tx() must be robust against skbs from raw sockets that
have invalid IPv4 and UDP headers.

Add checks that:
- the transport header has been found
- there is enough space between network and transport header offset
  for an IPv4 header
- there is enough space after the transport header offset for a
  UDP header

Fixes: 7c236c43b838 ('sfc: Add support for IEEE-1588 PTP')
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/net/ethernet/sfc/ptp.c b/drivers/net/ethernet/sfc/ptp.c
index 03acf57df045..93a61a157d10 100644
--- a/drivers/net/ethernet/sfc/ptp.c
+++ b/drivers/net/ethernet/sfc/ptp.c
@@ -989,7 +989,11 @@ bool efx_ptp_is_ptp_tx(struct efx_nic *efx, struct sk_buff *skb)
                 skb->len >= PTP_MIN_LENGTH &&
                 skb->len <= MC_CMD_PTP_IN_TRANSMIT_PACKET_MAXNUM &&
                 likely(skb->protocol == htons(ETH_P_IP)) &&
+                skb_transport_header_was_set(skb) &&
+                skb_network_header_len(skb) >= sizeof(struct iphdr) &&
                 ip_hdr(skb)->protocol == IPPROTO_UDP &&
+                skb_headlen(skb) >=
+                skb_transport_offset(skb) + sizeof(struct udphdr) &&
                 udp_hdr(skb)->dest == htons(PTP_EVENT_PORT);
 }