[PATCH 3.11 004/233] sfc: Add length checks to efx_xmit_with_hwtstamp() and efx_ptp_is_ptp_tx()

[Luis Henriques]

3.11.10.4 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ben Hutchings <bhutchings at solarflare.com>

commit e5a498e943fbc497f236ab8cf31366c75f337ce6 upstream.

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 at solarflare.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/ethernet/sfc/ptp.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/sfc/ptp.c b/drivers/net/ethernet/sfc/ptp.c
index b495394..6ddec68 100644
--- a/drivers/net/ethernet/sfc/ptp.c
+++ b/drivers/net/ethernet/sfc/ptp.c
@@ -982,7 +982,11 @@ 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);
 }
 
-- 
1.8.3.2