From 043d28507ef7c5fdc34866f5e3b27a72bd0cd072 Mon Sep 17 00:00:00 2001

From: Stefan Hajnoczi <stefanha@redhat.com>

Date: Wed, 15 Jul 2015 18:17:00 +0100

Subject: [PATCH 3/7] rtl8139: skip offload on short Ethernet/IP header

Transmit offload features access Ethernet and IP headers the packet.  If

the packet is too short we must not attempt to access header fields:

  int proto = be16_to_cpu(*(uint16_t *)(saved_buffer + 12));

  ...

  eth_payload_data = saved_buffer + ETH_HLEN;

  ...

  ip = (ip_header*)eth_payload_data;

  if (IP_HEADER_VERSION(ip) != IP_HEADER_VERSION_4) {

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

---

 hw/net/rtl8139.c | 5 +++++

 1 file changed, 5 insertions(+)

diff --git a/tools/qemu-xen/hw/net/rtl8139.c b/tools/qemu-xen/hw/net/rtl8139.c

index 2f12d42..d377b6b 100644

--- a/tools/qemu-xen/hw/net/rtl8139.c

+++ b/tools/qemu-xen/hw/net/rtl8139.c

@@ -2164,6 +2164,11 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s)

         {

             DPRINTF("+++ C+ mode offloaded task checksum\n");

+            /* Large enough for Ethernet and IP headers? */

+            if (saved_size < ETH_HLEN + sizeof(ip_header)) {

+                goto skip_offload;

+            }

+

             /* ip packet header */

             ip_header *ip = NULL;

             int hlen = 0;

-- 

2.1.4