From 30aa7be430e7c982e9163f3bcc745d3aa57b6aa4 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Wed, 15 Jul 2015 18:17:03 +0100 Subject: [PATCH 6/7] rtl8139: skip offload on short TCP header TCP Large Segment Offload accesses the TCP header in the packet. If the packet is too short we must not attempt to access header fields: tcp_header *p_tcp_hdr = (tcp_header*)(eth_payload_data + hlen); int tcp_hlen = TCP_HEADER_DATA_OFFSET(p_tcp_hdr); Signed-off-by: Stefan Hajnoczi --- hw/net/rtl8139.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/hw/net/rtl8139.c b/hw/net/rtl8139.c index ed2b23b..c8f0df9 100644 --- a/hw/net/rtl8139.c +++ b/hw/net/rtl8139.c @@ -2224,6 +2224,11 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s) if ((txdw0 & CP_TX_LGSEN) && ip_protocol == IP_PROTO_TCP) { + /* Large enough for the TCP header? */ + if (ip_data_len < sizeof(tcp_header)) { + goto skip_offload; + } + int large_send_mss = (txdw0 >> 16) & CP_TC_LGSEN_MSS_MASK; DPRINTF("+++ C+ mode offloaded task TSO MTU=%d IP data %d " -- 2.1.4