From 32e2f1ebf0d979c5ccc7e934ea9729e956d6aa52 Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Fri, 31 Jul 2015 15:59:46 +0200
Subject: [PATCH 5/7] rtl8139: check IP Total Length field (CVE-2015-5165)

Message-id: <1438358388-10575-6-git-send-email-stefanha@redhat.com>
Patchwork-id: 67240
O-Subject: [RHEL-7.1.z qemu-kvm EMBARGOED PATCH 5/7] rtl8139: check IP Total Length 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 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: Miroslav Rezanina <mrezanin@redhat.com>
---
 hw/net/rtl8139.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/hw/net/rtl8139.c b/hw/net/rtl8139.c
index 7efc0b5..61bc34c 100644
--- a/hw/net/rtl8139.c
+++ b/hw/net/rtl8139.c
@@ -2183,7 +2183,12 @@ 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)
             {
-- 
1.8.3.1