rtl8139: check IP Total Length field

The IP Total Length field includes the IP header and data.  Make sure it
is valid and does not exceed the Ethernet payload size.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

diff --git a/hw/net/rtl8139.c b/hw/net/rtl8139.c
index cd5ac0581baa8df393ca1a747685e0f19c243e64..ed2b23b9087ac340db590e7f8a37fde3bb342b2f 100644 (file)
--- a/hw/net/rtl8139.c
+++ b/hw/net/rtl8139.c
@@ -2205,7 +2205,12 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s)
             }
 
             ip_protocol = ip->ip_p;
-            ip_data_len = be16_to_cpu(ip->ip_len) - hlen;
+
+            ip_data_len = be16_to_cpu(ip->ip_len);
+            if (ip_data_len < hlen || ip_data_len > eth_payload_len) {
+                goto skip_offload;
+            }
+            ip_data_len -= hlen;
 
             if (txdw0 & CP_TX_IPCS)
             {