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>

diff --git a/hw/rtl8139.c b/hw/rtl8139.c
index ca664a7f560b78a6848e2672c6e3fac10609c324..fae9492dc7faff04a0b1e67764934b743abfc909 100644 (file)
--- a/hw/rtl8139.c
+++ b/hw/rtl8139.c
@@ -2181,7 +2181,12 @@ 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)
             {