From a8cef763585fecc8b89d006efca0e000df923d36 Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Fri, 31 Jul 2015 15:59:48 +0200
Subject: [PATCH 7/7] rtl8139: check TCP Data Offset field (CVE-2015-5165)

Message-id: <1438358388-10575-8-git-send-email-stefanha@redhat.com>
Patchwork-id: 67242
O-Subject: [RHEL-7.1.z qemu-kvm EMBARGOED PATCH 7/7] rtl8139: check TCP Data Offset field (CVE-2015-5165)
Bugzilla: 1248764
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
RH-Acked-by: Xiao Wang <jasowang@redhat.com>
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>

The TCP Data Offset field contains the length of the header.  Make sure
it is valid and does not exceed the IP data length.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 hw/net/rtl8139.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/net/rtl8139.c b/hw/net/rtl8139.c
index c9bf454..4f89328 100644
--- a/hw/net/rtl8139.c
+++ b/hw/net/rtl8139.c
@@ -2231,6 +2231,11 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s)
 
                 int tcp_hlen = TCP_HEADER_DATA_OFFSET(p_tcp_hdr);
 
+                /* Invalid TCP data offset? */
+                if (tcp_hlen < sizeof(tcp_header) || tcp_hlen > ip_data_len) {
+                    goto skip_offload;
+                }
+
                 /* ETH_MTU = ip header len + tcp header len + payload */
                 int tcp_data_len = ip_data_len - tcp_hlen;
                 int tcp_chunk_size = ETH_MTU - hlen - tcp_hlen;
-- 
1.8.3.1