From 5ec13dc4ed1c536de9711cb05af88609d073abf9 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Fri, 31 Jul 2015 15:59:42 +0200 Subject: [PATCH 07/13] rtl8139: avoid nested ifs in IP header parsing (CVE-2015-5165) Message-id: <1438358388-10575-2-git-send-email-stefanha@redhat.com> Patchwork-id: 67236 O-Subject: [RHEL-7.1.z qemu-kvm EMBARGOED PATCH 1/7] rtl8139: avoid nested ifs in IP header parsing (CVE-2015-5165) Bugzilla: 1248766 RH-Acked-by: Dr. David Alan Gilbert RH-Acked-by: Xiao Wang RH-Acked-by: Laszlo Ersek Transmit offload needs to parse packet headers. If header fields have unexpected values the offload processing is skipped. The code currently uses nested ifs because there is relatively little input validation. The next patches will add missing input validation and a goto label is more appropriate to avoid deep if statement nesting. Signed-off-by: Stefan Hajnoczi Signed-off-by: Miroslav Rezanina --- hw/net/rtl8139.c | 41 ++++++++++++++++++++++------------------- 1 file changed, 22 insertions(+), 19 deletions(-) diff --git a/hw/net/rtl8139.c b/hw/net/rtl8139.c index d08106b..e3b594f 100644 --- a/hw/net/rtl8139.c +++ b/hw/net/rtl8139.c @@ -2152,28 +2152,30 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s) size_t eth_payload_len = 0; int proto = be16_to_cpu(*(uint16_t *)(saved_buffer + 12)); - if (proto == ETH_P_IP) + if (proto != ETH_P_IP) { - DPRINTF("+++ C+ mode has IP packet\n"); - - /* not aligned */ - eth_payload_data = saved_buffer + ETH_HLEN; - eth_payload_len = saved_size - ETH_HLEN; - - ip = (ip_header*)eth_payload_data; - - if (IP_HEADER_VERSION(ip) != IP_HEADER_VERSION_4) { - DPRINTF("+++ C+ mode packet has bad IP version %d " - "expected %d\n", IP_HEADER_VERSION(ip), - IP_HEADER_VERSION_4); - ip = NULL; - } else { - hlen = IP_HEADER_LENGTH(ip); - ip_protocol = ip->ip_p; - ip_data_len = be16_to_cpu(ip->ip_len) - hlen; - } + goto skip_offload; } + DPRINTF("+++ C+ mode has IP packet\n"); + + /* not aligned */ + eth_payload_data = saved_buffer + ETH_HLEN; + eth_payload_len = saved_size - ETH_HLEN; + + ip = (ip_header*)eth_payload_data; + + if (IP_HEADER_VERSION(ip) != IP_HEADER_VERSION_4) { + DPRINTF("+++ C+ mode packet has bad IP version %d " + "expected %d\n", IP_HEADER_VERSION(ip), + IP_HEADER_VERSION_4); + goto skip_offload; + } + + hlen = IP_HEADER_LENGTH(ip); + ip_protocol = ip->ip_p; + ip_data_len = be16_to_cpu(ip->ip_len) - hlen; + if (ip) { if (txdw0 & CP_TX_IPCS) @@ -2369,6 +2371,7 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s) } } +skip_offload: /* update tally counter */ ++s->tally_counters.TxOk; -- 1.8.3.1