From 75e2b0065184cf33773b0ec064bef492a968e874 Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Thu, 30 Jul 2015 14:34:48 +0200
Subject: [PATCH 1/7] rtl8139: avoid nested ifs in IP header parsing
(CVE-2015-5165)
Message-id: <1438266894-23344-2-git-send-email-stefanha@redhat.com>
Patchwork-id: 67222
O-Subject: [virt-devel] [RHEV-7.1.z qemu-kvm-rhev EMBARGOED PATCH 1/7] rtl8139: avoid nested ifs in IP header parsing (CVE-2015-5165)
Bugzilla: 1248768
RH-Acked-by: Xiao Wang <jasowang@redhat.com>
RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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 <stefanha@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
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 745e23f..80cd2ac 100644
--- a/hw/net/rtl8139.c
+++ b/hw/net/rtl8139.c
@@ -2160,28 +2160,30 @@ 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)
@@ -2377,6 +2379,7 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s)
}
}
+skip_offload:
/* update tally counter */
++s->tally_counters.TxOk;
--
1.8.3.1