References: bsc#939712 XSA-140 From 9a084807bf6ca7c16d997a236d304111894a6539 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Wed, 15 Jul 2015 18:17:04 +0100 Subject: [PATCH 7/7] rtl8139: check TCP Data Offset field 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 --- hw/net/rtl8139.c | 5 +++++ 1 file changed, 5 insertions(+) Index: xen-4.5.1-testing/tools/qemu-xen-dir-remote/hw/net/rtl8139.c =================================================================== --- xen-4.5.1-testing.orig/tools/qemu-xen-dir-remote/hw/net/rtl8139.c +++ xen-4.5.1-testing/tools/qemu-xen-dir-remote/hw/net/rtl8139.c @@ -2250,6 +2250,11 @@ static int rtl8139_cplus_transmit_one(RT 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;