From 3ad3c2624c80f288c612ade035e5f3d82ba6de5d Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Thu, 30 Jul 2015 14:34:53 +0200
Subject: [PATCH 6/7] rtl8139: skip offload on short TCP header (CVE-2015-5165)
Message-id: <1438266894-23344-7-git-send-email-stefanha@redhat.com>
Patchwork-id: 67227
O-Subject: [virt-devel] [RHEV-7.1.z qemu-kvm-rhev EMBARGOED PATCH 6/7] rtl8139: skip offload on short TCP header (CVE-2015-5165)
Bugzilla: 1248768
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
RH-Acked-by: Xiao Wang <jasowang@redhat.com>
RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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 <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 22aef55..99d8f4a 100644
--- a/hw/net/rtl8139.c
+++ b/hw/net/rtl8139.c
@@ -2210,6 +2210,11 @@ 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 "
--
1.8.3.1