From ee6e48767c88f98ad1cc292fb45c6e35847d67e5 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Sat, 1 Aug 2015 08:39:32 -0400 Subject: [PATCH 6/7] rtl8139: skip offload on short TCP header (CVE-2015-5165) RH-Author: Stefan Hajnoczi Message-id: <1438418373-7324-7-git-send-email-stefanha@redhat.com> Patchwork-id: 67263 O-Subject: [virt-devel] [RHEL-6.7.z qemu-kvm EMBARGOED PATCH 6/7] rtl8139: skip offload on short TCP header (CVE-2015-5165) Bugzilla: 1248761 RH-Acked-by: Dr. David Alan Gilbert RH-Acked-by: Xiao Wang RH-Acked-by: Laszlo Ersek 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 Signed-off-by: Jeff E. Nelson --- hw/rtl8139.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/hw/rtl8139.c b/hw/rtl8139.c index 798dcab..835b641 100644 --- a/hw/rtl8139.c +++ b/hw/rtl8139.c @@ -2203,6 +2203,11 @@ 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; + } + #if defined (DEBUG_RTL8139) int large_send_mss = (txdw0 >> 16) & CP_TC_LGSEN_MSS_MASK; #endif -- 2.1.0