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From 33ea847dbe677a3df68fecac80636050f72286ae Mon Sep 17 00:00:00 2001
From: Michael S. Tsirkin <mst@redhat.com>
Date: Wed, 14 May 2014 08:31:42 +0200
Subject: [PATCH 11/31] virtio-net: out-of-bounds buffer write on load

RH-Author: Michael S. Tsirkin <mst@redhat.com>
Message-id: <1400056285-6688-2-git-send-email-mst@redhat.com>
Patchwork-id: 58856
O-Subject: [PATCH qemu-kvm RHEL7.1] virtio-net: out-of-bounds buffer write on load
Bugzilla: 1095685
RH-Acked-by: Dr. David Alan Gilbert (git) <dgilbert@redhat.com>
RH-Acked-by: Juan Quintela <quintela@redhat.com>
RH-Acked-by: Xiao Wang <jasowang@redhat.com>
RH-Acked-by: Amos Kong <akong@redhat.com>

CVE-2013-4149 QEMU 1.3.0 out-of-bounds buffer write in
virtio_net_load()@hw/net/virtio-net.c

>         } else if (n->mac_table.in_use) {
>             uint8_t *buf = g_malloc0(n->mac_table.in_use);

We are allocating buffer of size n->mac_table.in_use

>             qemu_get_buffer(f, buf, n->mac_table.in_use * ETH_ALEN);

and read to the n->mac_table.in_use size buffer n->mac_table.in_use *
ETH_ALEN bytes, corrupting memory.

If adversary controls state then memory written there is controlled
by adversary.

Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
(cherry picked from commit 98f93ddd84800f207889491e0b5d851386b459cf)

Bugzilla: 1095685
Tested: lightly on developer's box
Brew build: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=7452039
---
 hw/net/virtio-net.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 hw/net/virtio-net.c |   15 +++++++++++----
 1 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 007cc2a..f72be9f 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1273,10 +1273,17 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
         if (n->mac_table.in_use <= MAC_TABLE_ENTRIES) {
             qemu_get_buffer(f, n->mac_table.macs,
                             n->mac_table.in_use * ETH_ALEN);
-        } else if (n->mac_table.in_use) {
-            uint8_t *buf = g_malloc0(n->mac_table.in_use);
-            qemu_get_buffer(f, buf, n->mac_table.in_use * ETH_ALEN);
-            g_free(buf);
+        } else {
+            int64_t i;
+
+            /* Overflow detected - can happen if source has a larger MAC table.
+             * We simply set overflow flag so there's no need to maintain the
+             * table of addresses, discard them all.
+             * Note: 64 bit math to avoid integer overflow.
+             */
+            for (i = 0; i < (int64_t)n->mac_table.in_use * ETH_ALEN; ++i) {
+                qemu_get_byte(f);
+            }
             n->mac_table.multi_overflow = n->mac_table.uni_overflow = 1;
             n->mac_table.in_use = 0;
         }
-- 
1.7.1